Ion guide with an electric field region of adjustable length

Abstract

The present invention provides a system including an ion guide having an electric field region of a configurable length. [Solution] The ion guide includes a series of electrodes positioned between a first end and a second end of the ion guide. The power supply is configured to simultaneously apply a set of RF voltage waveforms to the series of electrodes, a set of first DC voltages to a set of first electrodes adjacent to the first end, and a set of second DC voltages to a set of second electrodes adjacent to the second end. The set of first DC voltages is configured to generate a first electric field within a first region of the ion guide, and the set of second DC voltages is configured to generate a second electric field within a second region of the ion guide, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Patent Application No. 63 / 702,526, filed on 2 October 2024 under Section 119(e) of the U.S. Patent Act, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to an ion guide having an electric field region of a configurable length. [Background technology]

[0003] Mass spectrometry has often been called the "gold standard" tool for the identification and analysis of various classes of compounds. Much of the strength of mass spectrometry lies in the ability of modern mass spectrometers to separate, store, and subsequently manipulate specific ion species of interest, selected from the numerous ion species generally produced by the ionization of any given sample mixture, via ion fragmentation or ion-ion chemical reactions. In many types of mass spectrometers, quadrupole mass filters are often employed to perform the ion separation function. For example, in triple quadrupole or quadrupole time-of-flight (Q-TOF) mass spectrometers, the mass filter is positioned before the mass spectrometer. The mass filter can receive an ion stream consisting of various ion species with different mass-to-charge (m / z) ratios. Specific pairs of direct-current (DC) and oscillating radio-frequency (RF) voltages may be applied to the rod electrodes of the mass filter to separate specific ion species with a particular m / z. Applying appropriately sized DC and RF voltages allows only a narrow range of m / z values ​​encompassing the specific m / z of interest to pass through the mass filter. This operation neutralizes and removes all other ions with different m / z values ​​from the instrument. Thus, the ion species containing the target m / z are transferred through the mass filter to other downstream mass spectrometer components where the isolated ions can be manipulated and analyzed in various ways, without significant contamination from other ion species.

[0004] While mass filters perform important functions, they are still inefficient in that they always exclude all ions except for specific ions that are allowed to pass through the instrument by selecting the filter passband. As a result, more than 90 percent of potentially available compositionally relevant information can typically be wasted by mass filters at any given time.

[0005] To improve overall analytical efficiency, various types of preliminary separation devices have generally been employed upstream of the mass filter as a means of providing non-destructive initial coarse separation of ion species. Once separated by the preliminary separation device, the various coarsely separated ion groups can then be separately transferred to the mass filter for narrow-band separation of the target ion species. For earlier preliminary separation, a smaller proportion of ions will be discarded by the mass filter during each such separation.

[0006] One example of such a preliminary separation method is ion mobility spectroscopy (ion Mobility spectrometry (IMS) is commonly used to separate ionized molecules in the gas phase based on their mobility within a carrier buffer gas. For a general overview of the coupling of ion mobility spectrometers to mass spectrometers, readers should refer to Kanu et al. (Kanu, Abu B., Prabha Dwivedi, Maggie Tam, Laura Matz and Herbert H. Hill Jr. "Ion mobility-mass spectrometry." Journal of mass spectrometry 43, no.1 (2008):1-22). According to another separation method known as trapped ion mobility spectrometry (TIMS), ions are trapped along a non-uniform DC electric field (electric field gradient) by an canceling gas flow, or along a uniform DC electric field by a canceling gas flow with a non-uniform axial velocity profile (gas velocity gradient). The trapped ions are separated in space according to their ion mobility and then eluted (released) over time according to their mobility by adjusting either the gas velocity or the DC electric field. Details of TIMS technology are described, for example, in U.S. Patent No. 6,630,662 in the name of inventor Loboda, U.S. Patent No. 7,838,826(B1) in the name of inventor Park, and U.S. Patent No. 11,226,308 in the names of Rather and Michelmann.Further explanation is provided by Michelmann et al. (Michelmann, Karsten, Joshua A. Silveira, Mark E. Ridgeway, and Melvin A. Park. "Fundamentals of trapped ion mobility spectrometry." Journal of the American Society for Mass Spectrometry 26, no. 1 (2014): 14-24) and Silveira et al. (Silveira, Joshua A., Karsten Michelmann, Mark E. Ridgeway, and Melvin A. Park. "Fundamentals of trapped ion mobility spectrometry part II: fluid dynamics." Journal of the American Society for Mass Spectrometry 27, no. 4 (2016): 585-595).

[0007] Both ion mobility spectrometry techniques and trapped ion mobility spectrometry techniques use an ion guide configured to provide an axial DC electric field along their length. Such an axial electric field can be provided by proportioning the voltage applied between the inlet and outlet ends of the ion guide among a plurality of electrodes disposed between the inlet and outlet ends of the ion guide. As an example, the voltage can be proportioned among segments of the rod electrodes of a quadrupole or multipole ion guide device. Alternatively, as will be described in more detail later herein, the voltage can be proportioned, for example, among a plurality of mutually parallel electrode plates or among a plurality of thin electrode wires deposited or otherwise adhered on a substrate plate or wafer.

[0008] By providing appropriate power supplies and electrical connections, a so-called "traveling wave" DC voltage can be supplied to various rod segments of a segmented quadrupole ion guide, plate electrodes of a multilayer plate or multilayer ring ion guide, or electrode wires of a printed circuit board (U.S. Patent No. 6,812,453 in the name of inventors Bateman et al.). Generally, in such operation, a periodically fluctuating DC voltage is applied to individual rod segment electrodes, plate electrodes, or wires, causing the periodic phase to shift between pairs of electrodes, moving the potential well from the ion injection port end of the ion guide to its ion outlet end. Traveling DC voltage waves have been used to control ions in mass spectrometers according to several different configurations. The most common commercially available ion guide and mass spectrometer impaction cell employing DC traveling waves is the T-Wave® system offered by Waters Corporation (Milford, Massachusetts, USA). The T-Wave® system employs a stacked ring ion guide with radial ion confinement provided by RF voltage and axial ion propulsion provided by an added DC traveling wave.Other DC traveling wave configurations, known by the acronym "SLIM" (Structures for Lossless Ion Manipulation), have been developed at the Pacific Northwest National Laboratory, as described by Tolmachev et al. (Tolmachev, Aleksey V., Ian K. Webb, Yehia M. Ibrahim, Sandilya VB Garimella, Xinyu Zhang, Gordon A. Anderson, and Richard D. Smith. "Characterization of ion dynamics in structures for lossless ion manipulations." Analytical Chemistry 86, no.18(2014):9162-9168) and Ibrahim et al. (Ibrahim, Yehia M., Ahmed M. Hamid, Liulin Deng, Sandilya VB Garimella, Ian K. Webb, Erin S. Baker, and Richard D. Smith. "New frontiers for mass spectrometry based upon structures for Lossless ion manipulations. This is described in Analyst 142, no.7 (2017):1010-1021). SLIM ion guides employ a similar traveling wave concept to trap and propel ions, but using a modified electrode configuration suitable for printed circuit board mounting. T-Wave® and SLIM traveling wave systems are most commonly used at relatively high pressures (e.g., about 1 Torr), where the axial motion of ions is hindered by gas collisions, resulting in partial separation based on the collision cross-section.

[0009] Recently, ion guides have been described that are implemented by the operation of a traveling wave, not by a DC voltage, but instead by a main RF axial confinement waveform applied to a multi-pole rod segment or a plate electrode of a stacked ring structure. According to these teachings, various electrodes of an electrode array (e.g., an array of plate electrodes, rod electrode segments, printed circuit board electrodes, etc.) can be logically grouped into successive subsets of electrodes (e.g., subsets each containing three or more electrodes), whereby within each subset, different modulated RF waveforms are applied to each electrode of the subset. Examples include RF traveling waves generated via amplitude modulation (U.S. Patent No. 9,799,503 in the name of inventors Williams et al.) and frequency modulation (U.S. Patent No. 10,692,710 in the name of inventors Prabhakaran et al.). SUMMARY OF THE INVENTION

[0010] The following description presents a simplified summary of one or more aspects of the systems and methods described herein. This summary is not an extensive overview of all contemplated aspects, and is not intended to identify key or critical elements of all aspects, nor to delineate the scope of any or all aspects. Its sole purpose is to present one or more aspects of the systems and methods described herein as a prelude to the detailed description presented below.

[0011] An exemplary system is an ion guide comprising a first end, a second end, and a set of electrodes positioned between the first and second ends, configured to receive ions, wherein the set of electrodes defines the ion-occupied volume and the axis of the ion guide between the first and second ends. The system further comprises a power supply electrically coupled to the set of electrodes, the power supply applying a set of radio frequency (RF) voltage waveforms to the set of electrodes, the RF voltage waveforms configured to confine ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, the plurality of moving pseudopotential wells exerting a force that biases ions to move along the axis toward the second end, and simultaneously applying a first set of direct current (DC) voltages to a set of first electrodes included in the set of electrodes and adjacent to the first end, the first set of DC voltages is The system is configured to apply a first electric field in a first region of the ion guide corresponding to the location of the first set of electrodes, and simultaneously with the application of a set of RF voltage waveforms and a first set of DC voltages, to a second set of DC voltages to a second set of electrodes included in the series of electrodes and adjacent to the second end, wherein the second set of DC voltages is configured to apply a second electric field in a second region of the ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field. The first and second electric fields generate a force that biases ions to move along the axis toward the first end.

[0012] An exemplary system comprises a memory for storing instructions and one or more processors communicatively coupled to the memory and configured to execute instructions for carrying out a process, wherein the process is to instruct a power supply to apply a set of radio frequency (RF) voltage waveforms to a set of electrodes positioned between a first end and a second end of an ion guide, the ion guide being configured to receive ions, the set of electrodes defining the ion-occupied volume and the axis of the ion guide between the first end and the second end, and the RF voltage waveforms being configured to confine ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, the plurality of moving pseudopotential wells exerting a force that biases ions to move along the axis toward the second end, and simultaneously with the application of the set of RF voltage waveforms to the set of electrodes and adjacent to the first end The method includes instructing a power supply to apply a first set of direct current (DC) voltages to a first set of electrodes, the first set of DC voltages being configured to generate a first electric field in a first region of an ion guide corresponding to the location of the first set of electrodes, and simultaneously with the application of a set of RF voltage waveforms and the first set of DC voltages, instructing a power supply to apply a second set of DC voltages to a second set of electrodes included in the set of electrodes and adjacent to the second end, the second set of DC voltages being configured to generate a second electric field in a second region of an ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field, wherein the first and second electric fields generate a force that biases ions to move along the axis toward the first end.

[0013] An exemplary method involves instructing a power supply to apply a set of radio frequency (RF) voltage waveforms to a set of electrodes positioned between a first end and a second end of an ion guide, configured to receive ON, wherein the set of electrodes defines the ion-occupied volume and the axis of the ion guide between the first and second ends, and the RF voltage waveforms are configured to confine ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, which exert a force that biases ions to move along the axis toward the second end, and simultaneously instructing the power supply to apply a first set of DC voltages to a first set of electrodes included in the set of electrodes and adjacent to the first end. The method includes instructing a power supply to apply a second set of DC voltages to a second set of electrodes, which are included in the set of electrodes and adjacent to the second end, simultaneously with the application of the RF voltage waveform set and the first set of DC voltages, wherein the second set of DC voltages is configured to create a second electric field in a second region of the ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having a larger amplitude than the maximum amplitude of the first electric field, and the first and second electric fields generate a force that biases ions to move along the axis toward the first end.

[0014] An exemplary non-transient computer-readable medium, when executed, instructs a power supply to apply a set of radio frequency (RF) voltage waveforms to a set of electrodes positioned between a first end and a second end of an ion guide configured to receive ions, wherein the set of electrodes defines the ion-occupied volume and the axis of the ion guide between the first and second ends, and the RF voltage waveforms are configured to confine ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, which exert a force that biases ions to move along the axis toward the second end, and simultaneously applies a first set of direct current (DC) voltages to a set of first electrodes included in the set of electrodes and adjacent to the first end. The system stores instructions to perform a process including: instructing a power supply to apply a set of first DC voltages configured to create a first electric field in a first region of an ion guide corresponding to the location of a set of first electrodes; and simultaneously with the application of a set of RF voltage waveforms and the set of first DC voltages, instructing the power supply to apply a second set of DC voltages to a second set of electrodes included in a set of electrodes and adjacent to the second end, wherein the set of second DC voltages is configured to create a second electric field in a second region of an ion guide corresponding to the location of the set of second electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field, and the first and second electric fields generate a force that biases ions to move along the axis toward the first end. [Brief explanation of the drawing]

[0015] The accompanying drawings illustrate various embodiments and are part of this specification. The illustrated embodiments are merely examples and do not limit the scope of this disclosure. Throughout the drawings, the same or similar reference numerals indicate the same or similar elements. [Figure 1A] This is a schematic cross-sectional view of a known multilayer ring ion guide ion transport device. [Figure 1B] This is a schematic diagram of an exemplary plate electrode that can be used in a multilayer ring ion guide ion transport system. [Figure 1C] This is a schematic diagram of known ion manipulation and ion guide devices that can be used as ion transport devices. [Figure 1D] Figure 1C is a schematic diagram of known ion manipulation and electrode configurations on the surface of ion guide devices. [Figure 2A] This is a schematic cross-sectional view of one embodiment of an ion tunnel stacked ring ion guide according to this instruction, in which the direction of ion movement is made different for different mass-to-charge (m / z) ratios by applying a static, uniform DC axial electric field that counteracts the downstream movement of a pseudo-potential well generated by the application of a traveling radio frequency (RF) wave. [Figure 2B] Figure 2A is another schematic cross-section of the ion tunnel stacked ring ion guide, where ions move to various different stable regions according to their respective mass-to-charge (m / z) ratios and accumulate therein, due to the application of a static, non-uniform DC axial electric field opposite to the downstream movement of the pseudo-potential well. [Figure 2C] This is a schematic diagram of ion extraction from the stacked ring ion guide device shown in Figure 2A, in order of each m / z ratio, by tilting the amplitude (or multiple amplitudes) of the RF voltage applied to the electrodes of the device. [Figure 3A] This is a schematic cross-sectional view of the first embodiment of the ion funnel stacked ring ion guide according to this instruction, where the direction of ion movement is made different for different mass-to-charge (m / z) ratios by applying a static, uniform DC axial electric field that attracts ions toward the narrow downstream end of the funnel and counteracts the upstream movement of the pseudo-potential well generated by the application of a traveling RF wave. [Figure 3B] This instruction presents a revised version of the ion manipulation and ion guide device shown in Figure 1C. [Figure 4A]This is a set of simulation plots of the equilibrium positions of ions at various m / z ratios within an ion-guided ion separator device under the application of a DC axial electric field gradient, the direction of which is opposite to the direction of the traveling wave generated by RF. [Figure 4B] This is a set of simulation plots of the equilibrium positions of ions with various m / z ratios in an ion-guided ion separator device when a gradient is applied to the amplitude of a traveling wave-induced RF waveform in the presence of opposing, uniform DC axial electric fields. [Figure 5] This is a schematic diagram of a part of a mass spectrometer, including a quadrupole mass filter or other mass spectrometer components arranged in series with an ion optics device configured and operated according to this instruction. [Figure 6A] Figure 2A is a schematic cross-sectional view of the apparatus and the ion packets within it, further illustrating a schematic example of how the DC voltage can be distributed between the stacked electrodes to generate a static and uniform DC axial electric field. [Figure 6B] A uniform axial electric field to counteract the biasing of ions by the movement of a propagating pseudopotential well (pseudowave) generated by RF, according to some embodiments of this teaching.

number

number

number

[0016] This application relates to mass spectrometers and mass spectrometry. More specifically, this application relates to ion optical components, including ion guides, ion traps, and ion separation devices employed in mass spectrometers, and to methods of using such ion optical components within a mass spectrometer. All patents, patent application publications, and other publications referenced herein are incorporated herein by reference in their entirety as they are described herein in their entirety.

[0017] In some examples, various ion sorting and / or ion storage devices can be constructed by canceling out the m / z-dependent pseudopotential force (i.e., moving pseudopotential well) that drives ion movement in RF-modulated traveling wave devices with an opposing m / z-independent force, such as an opposing DC electric field, as a result of the m / z dependence of the pseudopotential force. Such RF-DC ion sorting devices may be configured to provide initial coarse separation and temporary storage of ion species independently of the gas flow. Such RF-DC sorting devices may be deployed under both high vacuum and medium vacuum conditions, as disclosed herein, and are therefore more versatile than conventional ion sorting devices. Existing DC traveling wave devices require RF confinement separate from the DC traveling wave to move ions, whereas the apparatus and methods described herein utilize RF voltage for both ion confinement and ion movement.

[0018] Since RF-induced traveling waves have an m / z-dependent force (i.e., a greater force for lower m / z values), it is possible to counteract this force with a second m / z-independent force. For example, a static counteracting DC axial electric field can be generated by applying a simple DC potential gradient across multiple electrodes. The combination of counteracting forces can then be used to spatially classify ions within an ion guide or ion trap device. Such a pair of counteracting applied forces produce three different ion behavior states, as follows: (1) Firstly, for ions with the smallest m / z value where the force due to the RF traveling wave dominates the DC electric field force, the movement will be in the direction of the traveling wave. (2) For ions with the largest m / z value dominating the DC axial electric field, the movement will be opposite to the direction of the traveling wave. (3) Finally, for ions with a specific critical m / z value, the RF-induced force and the DC potential gradient-induced force balance out so that the ion does not move in any direction and is trapped within a specific region within the ion optical device, the location of which depends on a specific m / z value and applied voltage.

[0019] In some embodiments, the coordinated application of an RF electric field and a static DC electric field allows the ion guide to be configured such that low m / z and high m / z ions are moved in opposite directions, while at the same time, ions with critical m / z values ​​are trapped in trap locations within the ion guide. According to some other embodiments, the gradient may be applied to either the RF electric field, the DC electric field, or both. In such cases, the trap locations become m / z-dependent, thereby trapping and spatially separating ions based on their respective m / z values. Thus, in such embodiments, ions can be spatially sorted along the length of the ion guide, similar to how ions in isoelectric focusing, such as in a liquid phase, move to a point in a pH gradient that neutralizes the ions. The RF electric field gradient can be generated by varying the RF amplitude V along the length of the device, or more simply by changing the electrode geometry, either by varying the axial spacing of the electrodes or the electrode opening diameter. The DC electric field gradient can be generated most easily by changing the resistors in the divider network used to generate the gradient.

[0020] The spatial and temporal ion separation and sorting provided by the apparatus described herein are independent of gas flow. However, the optimal operation of such apparatus can be achieved at ambient gas pressures in the range of 0.01 Torr to about 2 Torr. At lower pressures, if ions are drawn out of the pseudopotential wells by the opposing DC, gas collisions are insufficient, and ions cannot settle into adjacent pseudopotential wells. In such low-pressure regimes, ions may be pulled by the opposing DC electric field through or across several progressing RF pseudopotential wells. Such low-pressure behavior is detrimental to the final resolution of the separation. The strength of the ion mobility contribution will depend on the ionic properties, as well as various controllable parameters such as gas composition and gas temperature. Unfortunately, this ion mobility contribution is difficult to predict as a result of the time-varying RF electric field. Therefore, under certain circumstances, it may be necessary to perform appropriate calibration of the response of each apparatus under various selected experimental conditions and various classes of ions. In many embodiments, even at pressures in the range of 0.01 to 0.5 Torr, the contribution of ion mobility effects between ions can be small or even negligible compared to the effects caused by differences in ion mass-to-charge ratios or charge differences.

[0021] In this specification, unless implicitly or explicitly understood or otherwise stated, it should be understood that a word appearing in the singular form encompasses its plural counterpart, and a word appearing in the plural form encompasses its singular counterpart. Furthermore, unless implicitly or explicitly understood or otherwise stated, it should be understood that for any given component or embodiment described herein, any of the possible candidates or substitutes listed for that component may generally be used individually or in combination with each other. Furthermore, it should be understood that the figures shown herein are not necessarily drawn to scale, and some of the elements may be drawn simply to clarify the invention. Also, reference numerals may be repeated in various figures to indicate corresponding or similar elements. In addition, unless implicitly or explicitly understood or otherwise stated, it should be understood that any enumeration of candidates or substitutes is merely illustrative and not limiting.

[0022] Unless otherwise defined, all other technical and scientific terms used herein have the meanings generally understood by those skilled in the art to which this disclosure belongs. In case of any conflict, this specification, including definitions, shall prevail. It will be understood that there is an implicit “about” before any quantitative terms referred to herein, so as to be within the scope of this teaching. Similarly, the use of “comprise,” “comprises,” “comprising,” “contain,” “contains,” “containing,” “include,” “includes,” and “including” is not intended to be limiting. Where used herein, “a” or “an” may mean “at least one” or “one or more.” Also, the use of “or” is inclusive, and as a result the phrase “A or B” means when “A” is applicable, when “B” is applicable, or when both “A” and “B” are applicable.

[0023] As used herein, the term "DC" refers to a voltage applied to one or more electrodes of a mass spectrometer component (such as an ion tunnel or ion funnel), and does not necessarily imply the application or presence of current through those electrodes. Therefore, the term "DC" is used herein to distinguish the voltage referred to from an applied oscillating voltage that oscillates at a high frequency and is referred to as an "RF" voltage.

[0024] As used herein, the term “static,” as applied to a DC electric field (vector field) or RF amplitude, refers to a DC electric field or RF amplitude that is essentially constant over time for a given time period, with possible small fluctuations not exceeding 10 percent of the average electric field strength or average RF amplitude. The term “uniform,” as applied to a DC electric field, refers to a DC electric field that is maintained to have a magnitude and direction that does not fluctuate substantially except for insignificant statistical fluctuations over a length encompassing a series of electrodes traversing a series of electrodes extending, for example, the length of an ion optical component from the ion implantation port end to the ion exhaust port end. Conversely, the terms “gradient” and “non-uniform,” as applied to a DC electric field, refer to at least spatial fluctuations in the magnitude of the DC electric field across a series of electrodes, and a DC electric field that exhibits such fluctuations, respectively. Note that a “static” DC electric field can be either uniform or have a gradient. The term “uniform,” as applied to an RF amplitude, refers to an RF amplitude that is maintained to not fluctuate substantially over a length encompassing a series of electrodes. Conversely, the terms "gradient" and "non-uniform" applied to RF amplitude refer to the spatial variation of the applied amplitude across a series of electrodes.

[0025] As used herein, the terms “dynamic” and “gradient,” as applied to either a DC electric field or an RF amplitude, refer to a DC electric field or RF amplitude that is varied over time, either in a monotonically increasing or monotonically decreasing manner, over a period of time. The gradient of the magnitude of a DC electric field applied across a set of electrodes requires the gradient of the DC potential applied to a subset of those electrodes (i.e., one or more of them). Similarly, the gradient of the RF amplitude of an RF waveform applied across a set of electrodes requires the gradient of the RF amplitude applied to one or more of those electrodes.

[0026] A DC electric field or RF amplitude maintained in a static state over a first period may be maintained in a dynamic or tilted state at other times occurring either before or after the period, and vice versa. Similarly, a DC electric field or RF amplitude maintained in a uniform state over a first period may be maintained in a non-uniform state at other times, and vice versa. As used herein, the terms “urge” and “urges,” when used in relation to the effect of the direction of an applied force on one or more ions, do not necessarily mean that one or more ions are moved in that direction in response to a force, since the direction of movement of any ion at the time of force application depends on its initial momentum vector and the vector sum of all such applied forces.

[0027] As described above, so-called "multilayer ring ion guides" are frequently employed in mass spectrometry to guide or otherwise manipulate ions. In this specification, the term "multilayer ring ion guide" is used to refer to any of the following: an ion guide comprising a series or number of rings or ring-shaped electrodes; an ion guide comprising a series or number of plates or plate-like electrodes; and / or an ion guide comprising a series or number of printed circuit boards having electrode structures printed on a substrate surface. Multilayer ring ion guides are often used as either so-called "ion tunnels" or "ion funnels." Figure 1A is a schematic longitudinal cross-sectional view of a multilayer ring ion guide apparatus 10, which includes both an ion tunnel section 12a and an ion funnel section 12b. However, it should be noted that many apparatuses simply referred to in the art as "ion funnels" have both an ion tunnel section and an ion funnel section, as depicted in Figure 1A.

[0028] Generally speaking, the stacked ring ion guide device 10 comprises a plurality of closely spaced ring electrodes or plate electrodes 2. A schematic diagram of a typical individual ring or plate electrode 2 is provided in Figure 1B. For clarity, Figure 1A depicts only a small number of electrodes 2. It should be noted that in practice, a typical ion funnel or ion tunnel device may have more than 100 individual electrodes. Each ring or plate electrode 2 (Figure 1B) is typically circular and has an opening 8 defined by the inner surface 3 of the ring. Each ring electrode 2 may be mounted to a support structure (not shown) and may have one or more tabs, such as tabs 9, for providing electrical connections to one or more power sources (e.g., a voltage source and / or any other type of power source).

[0029] Within the ion tunnel, as exemplified by ion tunnel section 12a, all openings of the electrodes in this section have a constant diameter θ. TIn contrast, within the ion funnel section 12b, the diameters θ of the various openings generally decrease along the direction away from the ion implantation port end 13 of the device toward the ion exhaust port end 18. As used herein, the term “broad end” is used to refer to the end of the ion funnel section where the fluctuating opening diameter θ is largest, and the term “narrow end” is used to refer to the opposite end of the ion funnel section where the opening diameter is smallest. During operation, an oscillating radio frequency (RF) voltage is applied to the electrodes in a defined phase relationship to confine ions radially inside the device. According to a generally defined conventional phase relationship, the phase of the RF voltage waveform of each stacked electrode is out of phase by π radians (180 degrees) from the phase of each directly adjacent electrode. The collection of all openings of all electrodes 2 defines an ion-occupied volume 11, in which ions generally travel from the ion implantation port end 13 to the ion exhaust port end 18 of the device 10, as indicated by arrows on the longitudinal axis 16. In typical operation, a pseudo-potential well, centered on axis 16 and generated by the applied RF configuration, confines ions within the ion-occupied volume 11. The relatively large electrode openings at the ion implantation port end 13 and ion tunnel section 12a of the apparatus are generally employed to capture dispersed or diffused ion clouds. In contrast, as the electrode opening of the ion funnel section 12b narrows toward the ion outlet 18, the ion cloud is narrowed into a narrow beam that can pass through the narrow opening into the high-vacuum chamber. The movement of ions from the ion implantation port end toward the ion outlet can be facilitated by the gas flow into which the ions are drawn. Ions may also be biased in the same direction by providing a DC axial electric field generated by differentially supplying DC voltages to the electrodes 2.

[0030] Figure 1C is a schematic diagram of another known type of ion manipulating and ion guiding device 50, as taught in U.S. Patent No. 10,692,710. As described in the said patent, the device 50 comprises two spaced parallel substrate plates or wafers 51 and 53, each plate or wafer having a surface on which a plurality of electrodes are arranged. For example, the plates or wafers 51 and 53 may be substrates of a printed circuit board. The electrode support surfaces may face each other across a gap between the two substrate plates or wafers, as shown. A central axis 57 is defined to pass through the device 50. Each electrode support surface has an array of inner electrodes 55 and also has outer guard electrodes 52a, 52b. The outer guard electrodes 52a, 52b are positioned on both sides of the array of inner electrodes 55. The array of inner electrodes 55 and the outer electrodes 52a, 52b extend substantially along the length of the electrode support surfaces of the substrate plates or wafers 51, 53. During operation, ions can be confined within the gap between the electrode support surfaces and guided parallel to the central axis 57, as taught in U.S. Patent No. 10,692,710.

[0031] Figure 1D schematically shows a portion of the electrode support surface of an individual substrate plate or wafer 53 of a known ion manipulating and ion guiding device 50. In the example illustrated in Figure 1D, each of the outer guard electrodes 52a, 52b includes a single elongated electrode that is elongated parallel to the central axis 57. The electrode array 55 comprises a series of individual electrodes 7a, 7b, 7c, ..., 7m. Although 12 such individual electrodes are shown, the array 55 can comprise any number of electrodes. A voltage source (not shown) can apply a voltage to each electrode 7a-7m individually. As described above in the Background Art section of this specification, U.S. Patent No. 10,692,710 further teaches, using the ion manipulating device 50 as an example, that various electrodes of the inner electrode array 55 can be logically grouped into successive subsets of electrodes (e.g., sets each containing three or more electrodes). The patent further teaches that by providing each electrode of each subset with differently modulated RF waveforms, a traveling wave can be generated that tends to bias ions parallel to the central axis 57 passing through the apparatus 50.

[0032] Figure 2A is a schematic cross-sectional view of a first embodiment of the ion tunnel stacked ring ion guide 100 according to this teaching. The stacked ring ion guide 100 is depicted as comprising only the ion tunnel portion, but alternatively, it may comprise any number of ion funnel portions and combinations of ion tunnel portions. In the general operation of the device 100, an ion stream 115 containing an unseparated mixture of ion species is delivered to the ion-occupied volume 101 of the device through the ion injection port 113. By the operation of the device 100, the original mixture of ion species may be separated into several packets, for example, ion packets 117a, 117b, and 117c as shown, each containing a different subset of the original set of ion species. These partially separated ion packets may then be discharged from the device as a stream of ion packets 119 through the ion outlet 118.

[0033] The physical configuration of electrode 2 of apparatus 100 (Figure 2A) is similar to the physical configuration of the electrode in the ion tunnel portion 12a of the stacked ring ion guide 10, where each electrode has an opening of diameter θ0, and the collection of openings defines the ion-occupied volume 101. Despite this similarity, apparatus 100 differs from apparatus 10 (Figure 1A) in the following respects. (a) The electrodes are logically grouped in a stacked order of subsets of electrodes, each subset having exactly four electrodes (in this example). (b) The RF voltage waveform applied to the electrodes changes over time within each subset of electrodes to generate a plurality of pseudopotential wells in which ions tend to concentrate, thereby causing the pseudopotential wells to move in a desired direction parallel to the axis of the apparatus, and the set of moving pseudopotential wells is referred to herein as the RF traveling wave, or equivalently, the “pseudowave”. (c) An axial DC electric field is provided within the ion-occupied volume that tends to bias the ions in the direction opposite to the direction of movement of the pseudo-potential well. Figure 6A is a schematic cross-sectional reproduction of the apparatus and the ion packets within it of Figure 2A, further illustrating a schematic example of how the DC voltage V can be distributed between the stacked electrodes to generate a static and uniform DC axial electric field. Axial electric field vector near the axis of the apparatus

number

number

[0034] Specifically, with regard to logically grouping electrodes into subsets, Figure 2A depicts two such groups (i.e., subsets), each comprising a first electrode 2a, a second electrode 2b, a third electrode 2c, and a fourth electrode 2d. Although only two such groups are labeled in Figure 2A, it should be understood that in the illustrated embodiment, each grouping of four electrodes into subsets relates to all electrodes 2 of the device extending from the ion inlet 113 to the ion outlet 118. According to some alternative embodiments, some parts of the electrodes do not need to be organized into such groups. Although four electrodes per subset are illustrated, the number of electrodes per subset N may vary. e It is not necessarily limited to 4. More generally, N e The repeating distance L along the axis of the device 100 (parallel to arrows 115 and 119) is ≥ 3. R This is defined as the distance between consecutive electrodes 2a (or consecutive electrodes 2b, etc.).

[0035] Within each subset of the electrodes of device 100, the four electrodes of the subset differ in that, during operation, different RF voltage waveforms are supplied to each electrode, as further described below. In an embodiment, a first RF voltage waveform that is the same among all the electrodes 2a is supplied to all the electrodes 2a. Similarly, a second RF voltage waveform that is the same among all the electrodes 2b is supplied to all the electrodes 2b in an embodiment. Similarly, a third voltage waveform is applied to all the electrodes 2c, and a fourth voltage waveform is applied to all the electrodes 2d. Generally speaking, N e voltage waveforms are selected such that a set of moving pseudo-potential wells is generated along the axis of the device (coinciding with arrows 115 and 119), thereby forming a set of "traveling waves" that tend to bias ions along the axis. According to the example shown in FIG. 2A, the voltage waveforms are configured such that the traveling waves bias ions in a direction from the ion inlet 113 to the ion outlet 118 parallel to lines 115 and 119. However, according to some other embodiments further described below in this specification, the voltage waveforms may be configured to bias ions in the opposite direction.

[0036] According to some embodiments of the present teachings, the RF voltage waveforms applied to the electrodes of device 100 may be selected as described in U.S. Patent No. 9,799,503. This patent provides an example of a subset of four electrodes of a stacked ring ion guide, and respective RF voltage waveforms are supplied to the four electrodes such that a plurality of moving pseudo-potential wells generate traveling waves within the ion guide. According to the aforementioned U.S. Patent No. 9,799,503, the four RF voltage waveforms may be supplied according to the following first to fourth drive signals. V A =V1F(ω m t-φ1)e jωt First RF drive signal Equation 1a V B =V2F(ω m t-φ2)e jωt Second RF drive signal Equation 1b V C =V3F(ω m t-φ3)e jωtThird RF drive signal Equation 1c V D =V4F(ω m t-φ4)e jωt Fourth RF drive signal Equation 1d Here, t is time, V1~V4 are the amplitudes from zero to the peak, j is the imaginary unit, function F is a complex function of its argument, periodic with a period of 2π, scalar value φ1 is the first phase, scalar value φ2 is the second phase shifted by 90 degrees (π / 2 radians) from the first phase, scalar value φ3 is the third phase shifted by 180 degrees (π radians) from the first phase, scalar value φ4 is the third phase shifted by 270 degrees (3π / 2 radians) from the first phase, and ω>ω m The scalar values ​​ω and ω are such that m This can be an angular frequency in radians per second. The applied voltage is understood to be described by the real part of any resulting complex representation. The patent also provides specific examples of implementations of the representations of Equations 1a to 1d, with the applied voltage being as follows: V A =V0cos(ω m t)cos(ωt) First RF drive signal Equation 2a V B =V0cos(ω m t-π / 2)cos(ωt) Second RF drive signal Equation 2b V C =V0cos(ω m t-π)cos(ωt) Third RF drive signal Equation 2c V D =V0cos(ω m t-3π / 2)cos(ωt) 4th RF drive signal f c formula 2d As mentioned above, the number of electrodes per subset is not limited to four electrodes per subset, but can be any integer N. e (Here, N e This may include ≥3). In such cases, the various electrodes R of each subset and the various voltage waveforms V(t) supplied to the electrodes of each subset can be enumerated by the index variable i in order from the electrode closest to the inlet, as follows:

number

[0037] According to some other embodiments of this teaching, the RF voltage waveform supplied to the electrodes of the apparatus 100 is a frequency-modulated signal S represented by the following equation. FM The method may be selected as described in U.S. Patent No. 10,692,710, which describes generating a traveling wave by providing a frequency-modulated waveform driven by a [unspecified element].

[0038] S FM =V c cos(2πf c +βS MS ) Here, f C V is the "carrier frequency" (i.e., the frequency of an unmodulated standard RF voltage waveform), and V C is the voltage amplitude of the RF waveform, β is the frequency modulation index, and S MS This is a frequency-modulated period waveform of frequency, and f M is f C This is a lower frequency than that. This latter patent describes how the electrodes of a stacked ring ion guide are organized into subsets of eight electrodes each, thereby modulating the frequency period waveform S FM This provides a specific example where the phase changes by only 2π / 8 radians (45 degrees) between each pair of electrodes.

[0039] Referring again to Figure 2A, arrow 110 indicates the direction of movement of the pseudo-potential well (i.e., traveling wave) generated by the RF, which may be generated as described above. As indicated by arrow 110, the application of the RF waveform may be configured such that the traveling wave exerts a force on the ion that tends to bias the ion in a "forward" direction, generally from the ion inlet 113 to the ion outlet 118. However, in alternative embodiments, the direction of pseudo-potential well movement may be reversed relative to the direction of movement shown in Figure 2A by reversing the phase relationship of the driving waveforms applied within each subset of electrodes. Figure 2A also shows that this teaching also generates a static, uniform DC axial electric field that exerts a force on the ion that tends to counteract the force exerted by the pseudo-potential well movement. A schematic example of the magnitude of the static, uniform DC axial electric field is provided by plot 508 in Figure 6A. Thus, arrow 111 indicates the direction in which the same ion is biased to move by the applied static, uniform DC axial electric field. Therefore, according to the operation shown in Figure 2A, the DC axial electric field is applied in such a way that it tends to bias the ions in the "reverse" direction from the ion outlet 118 towards the ion inlet 113. However, it should be noted that if the direction of the pseudo-potential well movement is reversed from the direction shown in Figure 2A, and the traveling wave instead tends to bias the ions towards the ion inlet 113, the direction of the DC axial electric field is also reversed relative to the direction shown in Figure 2A, and the DC axial electric field thus reversed will bias the ions towards the ion outlet 118.

[0040] The DC axial electric field generated within the ion-occupied volume 101 may be generated in a known manner by dividing the end-to-end voltage difference along the length of the apparatus through the inclusion of a series of resistors between the electrical connections to the various electrodes 2. Alternatively, the DC axial electric field may be generated by any one of several other known methods.

[0041] As shown in Figure 2A, the opposing pseudopotential and DC axial electric field forces applied create three different ion behavior states, as follows: (1) Firstly, for ions with the smallest m / z value such that the force due to the RF traveling wave exceeds the DC electric field force (e.g., ions in ion packet 117a), the movement will be in the direction of the traveling wave, as indicated by the motion vector 118a. (2) For ions with the largest m / z value such that the DC axial electric field is dominant (e.g., ions in ion packet 117c), the motion will be opposite to the direction of the traveling wave, as indicated by the motion vector 118c. (3) Finally, for ions with a specific critical m / z value that depends on the applied voltage (e.g., ions in ion packet 117b), the RF-induced force and the DC gradient-induced force are in equilibrium, and such ions will not move in either direction. Therefore, when the apparatus 100 is operated as shown in Figure 2A, it simultaneously functions as (a) a mass filter that allows only ions with relatively low m / z values ​​(i.e., below critical values) to pass through the outlet flow 119 to downstream equipment (such as a quadrupole mass filter and / or collision cell and / or mass spectrometer), (b) a single mass-charged ion trap or ion accumulator for ions with critical m / z values, and (c) a filter that removes all ions with m / z values ​​greater than critical values.

[0042] Figure 2B is another schematic cross-sectional view of the ion tunnel stacked ring ion guide 100 as introduced in Figure 2A, but configured and operated in an alternative mode that causes differential movement of ions through the ion guide, as well as spatially separated trapping of ion species according to their respective mass-to-charge (m / z) ratios. According to the operating mode shown in Figure 2B, the applied static DC axial electric field counteracting the pseudopotential-induced traveling wave is not uniform, but instead decreases in magnitude in the overall direction from the ion outlet 118 to the ion injection port 113. Specifically, as indicated by arrow 112, the DC axial electric field continues to generate a force that tends to bias the ions in the "upstream" direction opposite to the "downstream" direction (as indicated by arrow 110) in which the ions are biased by the traveling wave. However, the magnitude of the DC axial electric field vector is non-uniform and decreases in the upstream direction. Under such operation, various ion species within the m / z range will be trapped within the ion-occupied volume as each such ion species moves to an axial position where the upstream DC axial electric field precisely balances with the downstream pseudopotential inductive force exerted on the mass-charge value of the ion species, and accumulates there. For example, in Figure 2B, the mass-charge ratio (m / z) L Packet 117a of the first ion having, mass-to-charge ratio (m / z) M Packet 117b of the second ion having, and mass-to-charge ratio (m / z) H For packet 117c of the third ion having the following characteristics, the approximate axial equilibrium position is shown, where (m / z) H >(m / z) M >(m / z) LAlthough only three packets of ions with a specific m / z value are illustrated in Figure 2B, in reality, there is generally a substantially continuous range of equilibrium positions for ions with m / z values ​​within a certain m / z range, and the equilibrium m / z value decreases in the overall direction toward the ion outlet 118. Additionally, certain ion species with small m / z values ​​outside the range may move toward the ion outlet, and certain other ion species with large m / z values ​​outside the range may move toward the ion inlet. Thus, in the operating mode schematically illustrated in Figure 2B, the device 100 functions as a multi-mass-charged ion sorting ion trap.

[0043] As shown in Figure 2B, in order to extract trapped ions at various equilibrium positions, the amplitude of the phase-shifted and / or frequency-modulated main RF voltage may be tilted upward over time (i.e., gradually increased) as described above, so that the equilibrium positions corresponding to all m / z values ​​move toward the ion outlet as the RF voltage amplitude is tilted, as shown by the displacement vectors 118a, 118b, and 118c in Figure 2C. Additionally or alternatively, the magnitude of the opposing DC electric field may be tilted downward (i.e., gradually decreased). In this example, the trapped ions with the smallest m / z value (e.g., the ions in packet 117a) pass through the ion outlet first, and the ions with the largest m / z value (e.g., the ions in packet 117c) exit last.

[0044] In an alternative embodiment, note that the direction of travel of the traveling wave and the direction of the opposing DC electric field may be opposite to those shown in FIGS. 2A-2C. In such an alternative embodiment, the ion species having the maximum m / z value will be the first to be ejected from the device if the “direction” of the slope of the RF amplitude (i.e., either an “upward” slope or a “downward” slope) of the traveling wave (urging the ions toward the ion inlet 113) and the “direction” of the slope of the magnitude of the DC electric field (urging the ions toward the ion outlet 118) are reversed. Many of the basic examples discussed herein refer to the slope of either the RF amplitude or the DC electric field, but more generally, the RF amplitude and the DC electric field may slope simultaneously, such that while sloping simultaneously, both the magnitude of the RF amplitude and the magnitude of the DC electric field increase or both decrease. In other examples, sloping simultaneously may include an increase in the RF amplitude and, simultaneously, a decrease in the magnitude of the DC electric field. In yet other instances, sloping simultaneously may include a decrease in the RF amplitude and, simultaneously, an increase in the magnitude of the DC electric field.

[0045] As described above, a stacked ring ion guide, which is in the form of an ion tunnel, can be fabricated to function as either (a) a single mass-to-charge ion trap or ion accumulator (as described with reference to Figure 2A) by providing a uniform DC axial electric field opposite to the traveling wave uniformly applied over the length of the device, or (b) a multiple mass-to-charge ion sorting ion trap if there is a longitudinal spatial gradient in either the provided opposite DC electric field and / or the propulsion force of the pseudo-wave. In the case of an ion tunnel device, the operation that creates a “longitudinal spatial gradient in the propulsion force of the pseudo-wave” requires providing different RF waveforms (e.g., different RF amplitudes) to the electrodes of the device at various different positions between the ion inlet and ion outlet. In such cases, the required electronics can be complex, expensive, and / or difficult to design or manufacture. However, in the case of an ion funnel ion guide device such as the ion funnel device 200 depicted in Figure 3A, the gradient in the depth of the pseudo-potential well, and the resulting gradient in the propulsion force, is created by the shape of the device. Specifically, within the ion funnel apparatus 200, the depths of the various pseudo-potential wells increase in the direction of ion funnel convergence (see, for example, Figure 1 of U.S. Patent No. 9,799,503), which essentially increases the proximity of the electrode edges to the ion beam in the same direction (centered near the device axis). Thus, using the direction of the traveling wave generated by the RF directed to bias the ions toward the ion implantation port 213 (arrow 210) and the direction of the DC electric field directed to bias the ions toward the ion outlet 218 (arrow 211), the apparatus 200 can operate as a multi-mass-charge ion selective ion trap without applying any electric field gradient. Using the configuration shown in Figure 3A, relatively "light" (small m / z) ions can be trapped in region 117a adjacent to the ion implantation port 213, while at the same time, relatively "heavy" (large m / z) ions are trapped in region 117c adjacent to the ion outlet 218. As mentioned above, the intermediate m / z ions are trapped within region 117b.Trapped ions can be released in reverse order of their m / z ratio by either tilting the magnitude of the DC electric field upward (i.e., to a larger value) and / or tilting the applied RF amplitude downward (i.e., to a smaller value).

[0046] Figure 3B shows a modified version of the ion manipulation and ion guiding device in Figure 1C, according to this instruction. The ion manipulation and ion guiding device 250 depicted in Figure 3B is modified from device 50 (Figure 1C) so that it can operate similarly to the operation of the ion funnel 200 (Figure 3A), as described above. In contrast to device 50, in which parallel plates or wafers 51 and 53 are configured to support an array of inner electrodes 55 and a set of outer guard electrodes 52a, 52b, the modified device 250 is configured such that the plates or wafers 251 and 253 converge toward each other along the direction away from the ion injection port 313 and toward the ion outlet 318. For example, as shown in Figure 3B, plates / wafers 251 and 253 are separated from each other by a first separation distance s1 at the ion implantation port 313 and by a second separation distance s2 at the ion outlet 318, where s1 > s2, and there is continuous convergence of plates / wafers 251 and 253 between the ion implantation port 313 and the ion outlet 318.

[0047] In some examples, RF traveling waves can be generated along the axis 57 of device 50 by manipulating a principal RF axial confinement waveform applied to a series of individual electrodes 7a, 7b, 7c, ... (see Figure 1D) of a series of mutually opposing electrode arrays 55. Additionally, a DC electric field to counteract the ion motion biased by the RF traveling waves can also be generated within either device 50 (Figure 1C) or a modified device 250 (Figure 3B). For example, a static, uniform DC electric field can be generated within either device 50 or a modified device 250 by distributing the DC potential difference applied between the ion implantation port 313 and the ion outlet 318 among a plurality of inner electrodes of each plate / wafer 251, 253. The distribution of the voltage difference can be achieved by a voltage divider system in known ways. Additionally or alternatively, an axial DC electric field may be generated, or an otherwise generated axial electric field may be supplemented by providing guard electrodes 52a, 52b of each plate / wafer to be made of an electrically resistive material (as opposed to a conductive material such as metal). For example, the resistive guard electrodes 52a and 52b may be formed from any one of several suitable materials having electrical resistive properties (e.g., doped glass, cermet, polymer, etc., but not limited to these).

[0048] This is because, within the device 250, the electrodes 55 of the two electrode arrays (one electrode array supported on each of the plates / wafers 251 and 253) gradually approach each other along the direction from the ion injection port 313 to the ion outlet 318, and thus a gradient exists in the depth of the pseudopotential well, with the well depth increasing in the same direction. The increasing well depth creates a gradient in the propulsion force provided by the traveling wave generated by the RF. Thus, if the traveling wave generated by the RF is configured to bias ions away from the ion outlet 318 toward the ion injection port 313 within the device 250, and the biasing of the traveling wave is counteracted by a static, uniform DC electric field that biases ions toward the ion outlet 318, then different ion species with different respective m / z values ​​will establish different respective equilibrium positions within the device. In this situation, the distribution of equilibrium positions is similar to that depicted in Figure 3A, with ions 117a having a smaller mass-to-charge ratio being closer to the ion injection port than ions 117b and 117c having a larger mass-to-charge ratio, and ion 117c having the largest mass-to-charge ratio being closest to the ion outlet. The trapped ions can then be emitted from device 250 in reverse order of their m / z ratio by either tilting the magnitude of the DC electric field upward (i.e., to a larger value) and / or tilting the applied RF amplitude downward (i.e., to a smaller value).

[0049] The following discussion relates to Figures 6A–6H, which are schematic graphs of various voltages and DC electric fields within an ion guide operating according to this instruction. In each of these figures, it is assumed that the ion inlet 113 at position 0 corresponds to the left side of the respective graph, and the ion outlet 118 at position L corresponds to the right side of the plot. It is also assumed that a set of pseudowaves is applied to the electrodes of each ion guide to bias the ions from the ion inlet to the ion outlet. In Figures 6C and 6E, the absolute values ​​of the applied DC voltages are plotted. When positively charged ions are introduced into an ion guide or ion separator device operating as described herein, the general movement of ions within the device is as described, provided that the applied DC voltage profile is of a general form such as the profiles shown in Figures 6C and 6E. However, when negatively charged ions are introduced into the apparatus, the general movement of ions within the apparatus is as described when the applied DC voltage profile has a general form that is a mirror image (i.e., reflected across the horizontal axis) of the profile shown in Figures 6C and 6E.

[0050] As described above, a uniform DC electric field can be applied to counteract the motion of a set of moving RF potential wells (i.e., a set of pseudowaves) in order to separate ions containing a specific m / z range within the ion guide (see, for example, Figure 2A). For example, plot 508 in Figure 6A depicts a uniform axial DC electric field that can be produced by applying a series of DC voltages to various individual electrodes of the ion guide, where the applied voltage increases linearly from the ion inlet to the ion outlet (i.e., plot 501 in Figure 6A). Alternatively, as described above, a non-uniform axial DC electric field can be applied to counteract the motion of pseudowaves in order to cause the ion guide to emit ions from the ion outlet in either increasing or decreasing m / z order (see, for example, Figure 2C).

[0051] Figure 6B shows the absolute size.

number

number

number

[0052] Regarding the use of an ion guide as an ion separation and sorting device (e.g., Figure 2C) in which ions are emitted in order of their m / z values, the mass spectral resolution R of the device can be adjusted by utilizing a non-uniform electric field profile, as schematically depicted in Figure 6D, which can be generated by applying a DC voltage to the electrodes according to the voltage profile shown by segments 504a and 504b in Figure 6E. Specifically, the magnitude of the axial DC electric field that counteracts the ion motion caused by the pseudowave.

number

[0053] Ions are introduced through the ion inlet 113 into an ion guide device configurable with a traveling RF voltage and a static DC voltage, as shown in Figures 6D and 6E. The location of the ion inlet 113 is indicated as position 0 in Figures 6D and 6E. A radio frequency (RF) voltage waveform is applied to the electrodes of the device, generating a set of traveling RF waves that create a pseudo-potential well that energizes ions through the device from the ion inlet 113 to the outlet 118 located at position L. Simultaneously, a DC voltage is applied to the electrodes, having a general form shown by the dashed lines 503a and 503b in Figure 6D, which generates an axial electric field that energizes ions toward the ion inlet 113. After ion introduction, the amplitude A of the applied RF voltage... RF The (m / z) value is tilted (i.e., increased) over time. Under such conditions, as previously described herein, packets of ions having different respective m / z values ​​separate from each other and move through the apparatus toward the ion outlet 118 at different speeds. Figure 6D schematically depicts the positions of the three packets of ions 517a, 517b, and 517c in the apparatus, respectively (m / z) L (m / z) M , and (m / z) H Having a mass-to-charge ratio of , at a specific time t1 during the slope before any of the ions reach the plateau region 503b of the DC electric field profile, (m / z) H >(m / z) M >(m / z) LTherefore, the instantaneous position of any such ion packet at any given time represents the axial position within the device where the instantaneous forward bias of the ion in the packet by a pseudowave, such as that produced by the tilted RF amplitude at a given time, slightly overcomes the reverse bias of the ion by the electrostatic field along the electric field segment 503a. As previously stated, these opposing forces cause the ion with the smallest m / z value (e.g., the ion in packet 517a) to move most rapidly toward the ion outlet, and as a result, these ions reach point p1 at time t1. The ion with the largest m / z value (e.g., the ion in packet 517c) moves most slowly, and as a result, only reaches point p3 at time t1. At the same time, the ion with an intermediate m / z value (e.g., the ion in packet 517b) reaches point p2.

[0054] Figure 6F is a schematic diagram of the position of the ion packet in Figure 6D at a second time t2 following time t1, where the applied RF amplitude is such that the forward biasing pseudopotential force on the ion in ion packet 517a is E along electric field intensity segment 503b. maxThe electrostatic force is initially equal to the maximum reverse biasing electrostatic force corresponding to the point, and then slopes to substantially exceed it. As a result, multiple portions of the ions in packet 517a are collected by individual moving pseudopotential wells, thereby transported downstream from position pc to the ion outlet 118 at position L in a conveyor belt manner. This movement of ions along the flat electric field strength profile 503b is relatively rapid compared to movement along the rising voltage profile 503a, because the additional slope of the RF amplitude is not satisfied by the corresponding increase in the DC electric field biasing in the reverse direction. Simulations of ion motion show that some of the ions in each ion packet may move in the reverse direction (i.e., towards the ion inlet 113) within the constant electric field region 503b, but they move less frequently than in the variable electric field region 503a. On average, the moving pseudopotential wells move the ions forward away from point pc towards the ion outlet 118, so the ions can efficiently escape from the region 503a near point pc.

[0055] As the ions in packet 517a are transported from position pc to position L, the ions in packets 517b and 517c remain at positions p1 and p2, upstream of position pc, as a result of the previous spatial separation of the packets of different ions. Since the forward-biasing pseudo-potential force at these positions is only slightly above (i.e., nearly above) the reverse-biasing DC electric field force, the RF amplitude is further tilted until the subsequent time t3 when packet 517b reaches position pc, so that the ions in both of these packets continue to move relatively slowly toward position pc. As shown in Figure 6G, further tilting of the RF amplitude causes relatively rapid transport of the ions in packet 517b from position pc to position L. Further additional tilting similarly transports the ions in packet 517c (not shown).

[0056] Referring to Figures 6G to 6H, the transport of ions through the ion guide, in the manner described above, temporally separates the appearance of ion packets with different m / z values ​​from the ion outlet 118 of the device by at least the flight time of the ions from position pc to the ion outlet 118. The axial electric field profile opposing the forward motion of the ions does not need to be precise, as shown in Figures 6D, 6F, and 6G. For example, a general form of voltage profile shown in Figure 6H, where the profile along the second segment 503b is not constant, can also be usefully employed. Simulations of ion motion and distribution show that the precise form of the electric field within the "constant" region (i.e., the region shown by the voltage profile segment 503b) is not important. Simulations show that the best m / z resolution is achieved when the electric field within the profile segment 503b is constant, but small fluctuations have little effect on performance. In any case, any gradient of the DC electric field within profile segment 503b should be smaller than the gradient of the DC electric field within profile region 503a, which is used for the initial spatial separation of ion species by m / z.

[0057] Furthermore, the amplitude A of the applied RF waveform RF The gradient of may be selected according to the requirements of the specific measurement. For example, if the ion guide device is employed as a mass spectrometer of the type that operates in general inspection mode and involves the detection of all ions emerging from the ion outlet, then A, as schematically depicted in Figure 7A, RF A continuous slope may be adopted. Figure 7A shows the difference in A over time. RFWhile a linear variation is illustrated, alternatively, the variation may be nonlinear, having a steeper slope (i.e., a faster increase in amplitude) at times during the gradient when ions emerging from the instrument are not expected to require detection at the maximum achievable resolution, and a shallower slope (i.e., a slower rate of amplitude increase) at other times when emerging ions are expected to require a higher level of m / z discrimination. For example, Figure 8 shows the expected achievable mass spectral resolution of an ion as a function of m / z at a constant RF gradient velocity. Figure 9 shows that a longer duration allocated to the completion of the gradient is expected to result in higher resolution. Figure 7B shows, for example, a longer residence time Δt at the time when a particular ion of interest is expected to emerge from the instrument, and a variable amplitude jump ΔA at the time when the ion of interest is not expected. RF This illustrates a discontinuous, stepwise gradient. The expected time of appearance of an ion with a particular m / z value can be predetermined by calibrating the passage time of known standard ions through the instrument under various conditions.

[0058] Figures 4A and 4B represent the simulated performance 300 and 350 of the ion sorting apparatus configured and operated according to this instruction. The simulated apparatus is 160 mm wide and has 320 electrodes and 160 pseudopotential wells. The simulation assumed a typical separation / equilibrium time of 40 milliseconds and operation in the presence of 100 mTorr nitrogen gas. The plots in Figure 4A represent the equilibrium positions of ions with various m / z ratios in such an apparatus under the application of a DC axial electric field gradient and simultaneously an RF waveform that does not vary over the length of the apparatus. In contrast, the plots in Figure 4B represent the equilibrium positions of the same ions under the application of an RF amplitude gradient over the length of the apparatus in the presence of a uniform DC axial electric field. Traces 301 (Figure 4A) and 351 (Figure 4B) both represent ions with a virtual m / z value of 500 Th. Similarly, traces 302 and 352 represent ions with an m / z ratio of 600 Th, traces 303 and 353 represent ions with an m / z ratio of 700 Th, traces 304 and 354 represent ions with an m / z ratio of 800 Th, traces 305 and 355 represent ions with an m / z ratio of 900 Th, and traces 306 and 356 represent ions with an m / z ratio of 1000 Th.

[0059] Figure 5 is a schematic diagram of a part of a mass spectrometer, including an ion filter 400 or other mass spectrometer components arranged in series with an ion transporter 500, configured according to the instructions described above. Apparatus 500 may comprise any embodiment illustrated in the accompanying drawings, and may comprise any other apparatus not illustrated in this teaching that operates in accordance with this teaching, including, but not limited to, other ion guides that can provide both axial electric field gradients (end-to-end or over only a portion of the device length) and longitudinal gradients (end-to-end or over only a portion of the device length) in RF amplitude or any other RF parameter.

[0060] As illustrated, the apparatus 400 is a quadrupole mass filter comprising four mutually parallel rod electrodes 401, which are maintained in alignment by a support structure 415 and which may also provide electrical connections to the rods. In other cases, the apparatus may comprise, but is not limited to, a multipole ion trap, a multipole fragmentation cell, an ion guide, or any type of mass spectrometer. Preferably, a controllable ion gate 410 is located between the ion outlet of the apparatus 500 and the ion inlet of the apparatus 400.

[0061] In the operation of the system depicted in Figure 5, the apparatus 500 provides an ion outlet stream 119, where, at any given point in time, the range of mass-charge (m / z) values ​​of the ions constituting the outlet stream 119 is narrowed compared to a wider range of m / z values ​​provided at the inlet end of the apparatus 500 in the inlet ion stream 115, where the (m / z) values ​​constituting the outlet stream 119 change over time to either larger or smaller m / z values. Thus, in practice, the operation of the apparatus 500 is similar to that of a conventional mass filter, where the mass-charge passband of the mass filter is scanned over time, except that the passband of the apparatus 500 is wider than that of a conventional mass filter, and ions within each passband range can be accumulated and temporarily stored in the apparatus 500 before being released from the apparatus. Thus, the apparatus 500 performs the function of ion accumulation, as well as the function of partially pre-separating ions before transferring them to the conventional apparatus 400. If the conventional instrument 400 is equipped with a quadrupole mass filter, such a mass filter can isolate a narrower m / z range, each isolation range containing a specific ion species of analyte.

[0062] The ion outlet flow 119 may be either continuous or discontinuous in time. The continuity of the delivery of the ion outlet flow to the apparatus 400 may be controlled by the operation of the ion gate 410, thereby limiting the m / z range of ions that can be transferred to the downstream apparatus during any given time interval. During the time when the ion gate 410 is closed (thereby limiting the transfer), packets of new ions from the inlet ion flow 115 may be accumulated and sorted within the upstream apparatus 500 as described above herein. At such times, the applied RF waveform and DC voltage are adjusted to cause sorting (e.g., Figure 2B). When the ion gate 410 is open, the internal RF waveform and DC voltage are adjusted to allow the accumulated ions to move out of the apparatus in either an increasing order of their m / z values ​​(e.g., Figure 2C) or a decreasing order (e.g., Figure 3A).

[0063] Figure 10A is a flowchart of a first method (Method 800) for operating an ion guide according to this teaching. In the first step, step 801 of Method 800, a pulse of ions containing a range of mass-to-charge (m / z) ratios is input to the first port of two separate ion ports of the ion guide. In step 802, the ions are temporarily trapped and / or accumulated in the ion guide at the end of the ion guide adjacent to the first port. The ions may be trapped and / or accumulated there by applying a DC voltage to the electrode near the first port, thereby temporarily creating a transient static potential well near that port. In the next step 803 (which may be performed prior to or concurrently with steps 801 and 802), a radio frequency (RF) voltage waveform is applied to a series of electrodes of the ion guide, which generates a number of pseudo-potential wells configured to bias the ions in a first direction, either away from the first ion port toward the second ion port or, alternatively, toward the first ion port. In step 805, performed concurrently with step 803, a DC potential is applied to each of the two or more electrodes, generating a DC electric field that biases the ions in the opposite direction to the biasing of the ions by the pseudo-potential well. The DC electric field may be uniform (i.e., constant magnitude that does not vary with position) or non-uniform (i.e., magnitude that varies with position) over the length of the ion guide. In an optional step 807, the applied RF amplitude and / or one or more applied DC potentials are gradually sloped over time in either an increasing or decreasing manner to facilitate the differential movement of ions toward the second ion port. Finally, in step 809, ions containing a range of m / z ratios that is reduced (i.e., a subset of the range) of the initially input ions are extracted from the second port of the ion guide. The extracted ions may be injected into a mass filter, collision cell, or another component of a mass spectrometer, such as a mass spectrometer.

[0064] Figure 10B is a flowchart of a second method (Method 810) for operating an ion guide according to this teaching. In step 811 of Method 810, a radio frequency (RF) voltage waveform is applied to a series of electrodes positioned between the ion implantation port and the ion outlet of the ion guide, generating a number of pseudopotential wells configured to bias ions away from the ion implantation port toward the ion outlet. In step 813, performed concurrently with step 811, each DC potential is applied to each of two or more electrodes that generate a DC electric field configured to bias ions away from the ion outlet toward the ion implantation port. The DC electric field may be uniform (i.e., constant magnitude with no position variation) or non-uniform (i.e., magnitude with position variation) along the length of the ion guide. Subsequently, in step 815, pulses of ions containing a range of mass-charge values ​​are injected into the ion guide through the ion implantation port. In step 817, (a) the amplitude of the applied RF waveform is increased, and / or (b) the magnitude of the applied DC electric field is gradually decreased to differentially move the ions through the ion guide toward the ion outlet. In step 819, the ions are extracted from the ion outlet in order of increasing mass-to-charge ratio. The extracted ions may be injected into another component of a mass spectrometer, such as a mass filter, collision cell, or mass spectrometer. According to a modification of method 810, step 815 may be performed before steps 811-813, and an additional step of trapping pulses of ions within the region of the ion guide adjacent to the ion injection port may be performed together with the execution of steps 811-813.

[0065] Figure 10C is a flowchart of a third method (Method 830) for operating an ion guide according to this teaching. In step 831, a radio frequency (RF) voltage waveform is applied to multiple electrodes of an ion funnel having an ion inlet end, an ion outlet end, and multiple plate or ring electrodes between the inlet and outlet ends, each having an opening whose diameter decreases from the inlet end to the outlet end, and the RF voltage waveform generates multiple pseudo-potential wells configured to bias ions toward the ion inlet and away from the ion outlet. In step 833, performed concurrently with step 831, each DC potential is applied to each electrode, thereby generating a DC electric field configured to bias ions away from the inlet end toward the outlet end. Then, in step 835, pulses of ions containing a range of mass-charge values ​​flow into the ion funnel through its ion inlet end. In the optional step 837, the magnitude (i.e., intensity) of the DC electric field toward the ion outlet end of the ion funnel may be increased by grading the DC voltage applied to the electrodes to facilitate the movement of ions toward the ion outlet end of the ion funnel. Finally, in step 839, the ions are extracted from the outlet end of the ion funnel in decreasing order of their m / z ratio. The extracted ions may be injected into a mass filter, impaction cell, or another component of a mass spectrometer, such as a mass spectrometer.

[0066] The descriptions contained herein are intended to serve as a basic explanation. The present invention is not intended to be limited in scope by the specific embodiments described herein, which are intended as single examples of individual aspects of the invention. Functionally equivalent methods and components are within the scope of the invention as defined by the claims. In addition to those shown and described herein, various other variations of the invention will be apparent to those skilled in the art. For example, a method for generating an axial DC electric field is described herein, in which an end-to-end DC voltage is proportionally distributed (e.g., by using a voltage divider) across a series or number of electrodes to which an RF voltage is also applied. However, many other means of generating an axial electric field within an ion guide are described, many of which utilize a set of auxiliary electrodes to generate the axial electric field. Such auxiliary electrodes are often separate from and added to a series or number of main electrodes that receive the RF voltage waveform. U.S. Patents 7,675,031 (Konicek et al.), 5,847,386 (Thomson et al.), 7,985,951 (Okumura et al.), 7,064,322 (Crawford et al.), 7,064,322 (Crawford et al.), and 6,417,511 (Russ, IV et al.) describe many alternative methods for generating axial or drag electric fields. Adapting one or more of these known axial electric field generation techniques to the methods and apparatus described herein would be considered and would be within the capabilities of those skilled in the art.

[0067] As another example of a modification of the above teaching, variations in the spacing between adjacent ring electrodes 2 (Figures 1A, 2A, 2B, and 2C), or between adjacent electrodes of the array 55 supported on the substrate (Figure 1C), may be used as an additional method to generate a longitudinal spatial gradient in the propulsion force of the RF-induced traveling wave. For example, the inter-electrode spacing can be varied continuously or discontinuously along the axial length of the ion guide or ion separator device according to this teaching, and this variation generates a corresponding variation in the depth of the pseudo-potential well along the length of the device.

[0068] As yet another example of a modification of the above teaching, refer here to Figures 11A and 11B. The virtual voltage plots depicted in Figures 11A and 11B, when considered together, provide an example of the application of two separate DC voltage profiles 930 and 940 to an ion guide device that alternate in time with respect to each other. The left end of each voltage profile corresponds to the ion inlet or "upstream" end of the ion guide device, and the right end of each profile corresponds to the ion outlet or "downstream" end of the device. During operation, each DC profile is supplied simultaneously with the supply of an RF-modulated traveling wave that generates an RF-induced pseudopotential well that biases the ion toward the downstream end of the device to which the DC profile is supplied. DC voltage profiles 930 and 940 are supplied to provide the ion with a force that counteracts the pseudopotential inductive force and thus biases the ion toward the upstream end of the device. Thus, the algebraic sign of the slopes of profiles 930 and 940 implicitly assumes that the ion is positively charged.

[0069] Each voltage profile in Figures 11A and 11B includes a series of steeply sloped segments 932 separated from each other by a series of shallowly sloped segments 933. The terms “steeply sloped” and “shallowly sloped” are used herein in a relative sense only and do not imply any specific numerical value of the slope or applied voltage. The steeply sloped segments of the voltage profile represent the upstream electric field vector.

number

number

number

[0070] The change from voltage profile 930 (Figure 11A) to voltage profile 940 (Figure 11B) and vice versa is equivalent to a simple leftward or rightward shift of a single profile, and this shift can be observed to be equal to a constant spatial width of the profile segment. However, by appropriately and finely controlling the distribution of voltage supplied to various individual electrode segments that generate the electric field, and the circulation of voltage supplied to those electrodes, the shift can be made much smaller than the segment width. In such cases, the positional changes of the voltage profile, as well as the positional changes of the "peaks" 936 and "troughs" 937 of the electric field magnitude profile, may be made to more closely approximate a continuous profile shift, and the positional changes of the peaks and troughs 936, 937 may be referred to as "DC traveling waves." By providing such upstream-moving DC traveling waves in conjunction with simultaneously providing downstream-moving RF traveling waves, if the upstream movement rate of peak 936 is controlled to match the movement rate of target ions along the length of the device, the separation and concentration of certain target "heavy" ion species can be promoted at the upstream end of the ion guide device. Generally, "light" ions also move toward the downstream end of the apparatus under such conditions, but with less efficiency. Conversely, downstream moving DC traveling waves can facilitate the separation and concentration of "light" ions at the downstream end of the apparatus, as well as / or their removal from the apparatus at the ion outlet. Various operating parameters can be controlled as needed.

[0071] It should be noted that as the gas pressure gradually increases beyond 0.01 Torr, the performance of the ion guide device described above gradually changes. This change is expected to result from the increased probability of collisions between ions and gas molecules as the gas pressure increases. When the pressure increases slightly beyond 0.01 Torr, the overall characteristics of the device performance remain as described above, but the m / z resolution and the speed at which ion species move through the device change. In general, higher gas pressures cancel out both the downstream and upstream biases produced by the applied voltage, but the effect of pressure is maximal with respect to RF traveling waves because the depth of the pseudopotential well decreases with increasing gas pressure. As a result, as the internal pressure increases, the effect of the m / z-independent force exerted on all ions by the applied DC electric field becomes more pronounced with respect to the bias exerted by RF traveling waves. Therefore, at such gas pressures, the performance of the ion guide device described above (e.g., m / z resolution, ion residence time) can be advantageously modified by controlling the gas pressure, depending on the requirements of a particular measurement, experiment, or analysis program.

[0072] As the gas pressure inside the ion guide device increases further, the ion-molecular collision effect becomes increasingly pronounced relative to the effects of the applied DC and RF voltages. Consequently, beyond a certain gas pressure, which depends on the device configuration (e.g., length, cross-sectional area, gas composition, etc.), the collision effect becomes dominant over the effect dependent on the m / z of the applied voltage, and the device's performance tends to resemble that of an ion mobility separator, with its performance being modulated by the applied DC and RF voltages. The performance of such an ion mobility device can be advantageously modified by controlling the magnitude of one or more applied RF voltage waveforms, or by controlling one of more of the frequencies of the applied voltage waveforms, depending on the requirements of a specific measurement, experiment, or analysis program.

[0073] Therefore, gas pressure can be considered an additional parameter to be taken into account during the calibration of the performance of an instrument operating as described by this instruction. More generally, gas pressure is one of many operating parameters, such as instrument length, instrument cross-sectional area, gas composition, and RF frequency, that can affect mass spectral results (e.g., mass spectral resolution and measurement rate) but are difficult to model theoretically when combined. Consequently, the behavior of the instrument should be calibrated for each specific instrument before operation so that the effects of these parameters are well understood in each case.

[0074] As described herein, most mass spectrometry experiments are inherently inefficient, with mass filters sometimes removing more than 99% of available ions. To mitigate this inefficiency, "ion scheduling" can be performed, as described herein, to accumulate ions before the ion filter in an ion guide (also known as an ion sorter). The ions can then be selectively released so that a smaller proportion are ultimately lost by the mass filter.

[0075] In some experiments, or during certain stages of an experiment, it may be beneficial to maximize the charge capacity of the ion guide. Charge capacity refers to how much charge the ion guide can hold in any given time. In other experiments, or during certain stages of an experiment, it may be beneficial to maximize the ion separation resolution. For example, during the initial stages of an experiment, when relatively low m / z ions are being emitted, a lower ion separation resolution is required to separate the same mass difference compared to higher m / z ions. Therefore, during these initial stages, it may be more beneficial to have a relatively high charge capacity compared to the ion separation resolution. As the experiment progresses, higher m / z ions are emitted. Therefore, during these later stages, it may be more beneficial to have a relatively high ion separation resolution compared to the charge capacity.

[0076] To this end, the ion separation resolution can be improved by generating a first electric field (i.e., a first DC electric field) in a first region of the ion guide (also referred to as the storage region) adjacent to the first end of the ion guide (e.g., the inlet to the ion guide), and generating a second electric field (i.e., a second DC electric field) in a second region of the ion guide (also referred to as the discharge region) adjacent to the second end of the ion guide (e.g., the outlet from the ion guide), wherein the second electric field is uniform across the second region and has a larger amplitude than the maximum amplitude of the first electric field.

[0077] In some examples, the first electric field is uniform across the first region of the ion guide. In this configuration, the amplitude of the first electric field can be set to be smaller than the amplitude of the second electric field by a predetermined threshold amount. For example, the amplitude of the first electric field may be set relatively low (e.g., less than 100 volts / meter) so as not to overwhelm the propagating field for the highest m / z of the subject. The amplitude of the second electric field can be set relatively high (e.g., about 400 volts / meter). In this configuration, the ions can be spatially separated within the first region due to space charge, with the lowest m / z species ending at the interface between the first and second regions, and the remaining ions aligning in m / z order.

[0078] Alternatively, the first electric field has a gradient across a first region of the ion guide. In this configuration, the first electric field may gradually increase across the ion guide, and the maximum amplitude of the first electric field is smaller than the amplitude of the second electric field. Thus, as explained in relation to Figures 6D and 6E, a relatively high ion separation resolution can be achieved by having a relatively long uniform electric field (i.e., a relatively long second region within the ion guide), which can result in a relatively short gradient electric field (i.e., a relatively short first region within the ion guide) because the ion guide is spatially constrained.

[0079] The terms “DC electric field” and “electric field” are used herein synonymously to refer to an electric field produced by a DC voltage. The terms “uniform” and “constant” are used herein synonymously to refer to an electric field that is uniform over space (e.g., over a particular region of an ion guide) (e.g., has a substantially uniform or constant amplitude) when referring to either a DC electric field or an electric field. A uniform electric field can be produced by a DC voltage that increases over space (e.g., over a particular region of an ion guide) according to a linear function. Similarly, the term “gradient” refers to a gradient or non-uniform electric field that increases over space (e.g., over a particular region of an ion guide) when referring to either a DC electric field or an electric field.

[0080] In some examples, the controller may dynamically adjust the relative lengths of the first and second electric fields to optimize the operation of the ion guide based on one or more conditions that work more favorably to the charge capacitance of the ion guide than to the ion separation resolution, or vice versa. As described herein, this can be achieved by implementing a power supply including a plurality of individually controllable DC voltage sources configured to be directly connected to various individual electrodes included in a set of electrodes of the ion guide. Impedance elements (e.g., resistors) interconnecting the electrodes create a voltage divider circuit that can be utilized to selectively provide a first set of DC voltages to a first set of electrodes closest to the first end of the ion guide, and a second set of DC voltages to a second set of electrodes closest to the second end of the ion guide.

[0081] In some examples, the first set of DC voltages may be set to increase according to a linear function, thereby creating a uniform electric field in the space defined by the first set of electrodes. Alternatively, the first set of DC voltages may be set to increase according to a quadratic (or other) function across the first set of electrodes, thereby creating a gradient electric field in the space defined by the first set of electrodes. The second set of DC voltages may be set to increase according to a linear function, thereby creating a uniform electric field in the space defined by the second set of electrodes.

[0082] To adjust the relative lengths of the first and second electric fields, the controller may selectively specify which electrodes are included in the first and second electrode sets (for example, by appropriately setting the DC voltage tapped into the voltage divider). In doing so, the optimal lengths of the first and second electric fields can be set before and / or during the experiment.

[0083] Figure 12 shows an exemplary configuration 1200 configured to selectively set the lengths of first and second electric fields within the ion-occupied volume of an ion guide. As shown, configuration 1200 may include an ion guide 1202, a power supply 1204, and a controller 1206. Configuration 1200 may include additional or alternative components that may be useful for a particular implementation.

[0084] The ion guide 1202 may be implemented by any of the ion guides described herein, as shown in Figure 12 as a cross-sectional side view. As shown, the ion guide 1202 includes a first end 1208-1, a second end 1208-2, and a series of electrodes 1210 (e.g., electrodes 1210-1 to 1210-n) positioned between the first end 1208-1 and the second end 1208-2. The electrodes 1210 define the ion-occupied volume 1212 within the ion guide 1202 and the axis 1214 of the ion guide between the first end 1208-1 and the second end 1208-2. The series of electrodes 1210 may include any suitable number of electrodes (e.g., 100 electrodes).

[0085] The power supply 1204 is electrically coupled to the electrode 1210 and can be implemented by any number of individually controllable power supplies. Exemplary implementations of the power supply 1204 are described herein.

[0086] As depicted in Figure 12, the power supply 1204 can simultaneously apply a set of RF voltage waveforms to a set of electrodes 1210, a set of first DC voltages to a set of first electrodes included in the set of electrodes 1210 and adjacent to the first end 1208-1, and a set of second DC voltages to a set of second electrodes included in the set of electrodes 1210 and adjacent to the second end 1208-2. The RF voltage waveforms are configured to confine ions within the ion-occupied volume 1212 and generate a plurality of migratory pseudopotential wells, which exert a force that biases the ions to move along axis 1214 toward the second end 1208-2. The set of first DC voltages is configured to generate a first electric field in a first region of the ion guide 1202 corresponding to the locations of the first set of electrodes. The set of second DC voltages is configured to generate a second electric field in a second region of the ion guide 1202 corresponding to the locations of the second set of electrodes. Both the first and second electric fields generate a force that moves the ion along axis 1214 toward the first end 1208-1.

[0087] As described herein, a first set of DC voltages may be configured to produce either a uniform electric field over a first region or a gradient electric field over a first region. A second set of DC voltages may be configured to produce a uniform electric field over a second region, the uniform electric field over the second region having an amplitude greater than the maximum amplitude of the first electric field.

[0088] The controller 1206 is coupled to the power supply 1204 and configured to control the operation of the power supply 1204. For example, the controller 1206 may instruct the power supply 1204 to apply an RF voltage waveform to a set of electrodes 1210, to apply a first set of DC voltages to a first set of electrodes, and to apply a second set of DC voltages to a second set of electrodes. The controller 1206 may be further configured to specify which electrodes included in the set of electrodes 1210 are included in the first set of electrodes, and which electrodes included in the set of electrodes 1210 are included in the second set of electrodes. Thus, the relative lengths of the first and second electric fields may be adjusted, set, or otherwise controlled by the controller 1206. These and other operations that may be performed by the controller 1206 are described herein.

[0089] The controller 1206 may be implemented by any combination of one or more computing devices. For example, the controller 1206 may be implemented by a computing device included in the mass spectrometer system, one or more computing devices configured to be communicatively coupled to the mass spectrometer system and / or the ion guide, and / or any other local and / or remote computing devices that may be useful in a particular implementation.

[0090] Figure 13 shows exemplary components of controller 1206. For example, controller 1206 may include, but is not limited to, memory facilities 1302 and processing facilities 1304 that are selectively and communicatively coupled to each other. Facilities 1302 and 1304 each include, or can be implemented by, hardware and / or software components (e.g., a processor, memory, a communication interface, instructions stored in memory for execution by the processor). In some examples, facilities 1302 and 1304 may be distributed among multiple devices and / or multiple locations to serve a particular implementation form. For example, facility 1302 may be distributed between one or more local computing resources and one or more remote computing resources communicatively coupled to the local computing resources via a network.

[0091] The storage unit 1302 may maintain (e.g., store) executable data used by the processing unit 1304 to perform any of the operations described herein. For example, the storage unit 1302 may store instruction 1306 which can be executed by the processing unit 1304 to perform any of the operations described herein. Instruction 1306 can be implemented by any suitable application, software, code, and / or other executable data instance. The storage unit 1302 may also maintain any data that is acquired, received, generated, managed, used, and / or transmitted by the processing unit 1304.

[0092] The processing unit 1304 may be configured to perform various processing operations described herein (for example, executing instructions 1306 stored in the storage unit 1302 for the purpose of performing them). It will be recognized that the operations and examples described herein are merely illustrative of the many different types of operations that may be performed by the processing unit 1304. In this description, any reference to an operation performed by the controller 1206 should be understood as being performed by the processing unit 1304 of the controller 1206. Furthermore, in this description, any operation performed by the controller 1206 may include the controller 1206 instructing or commanding another computing system, device, or apparatus to perform an operation.

[0093] Figure 14 shows an exemplary method 1400 for managing a power supply (e.g., power supply 1204) that may be performed by the controller 1206. Figure 14 shows exemplary operation according to one embodiment, but other embodiments may omit, add, rearrange, and / or modify any of the operations shown in Figure 14.

[0094] In operation 1402, the controller 1206 may instruct a power supply (e.g., power supply 1204) to apply a set of RF voltage waveforms to a series of electrodes positioned between a first end and a second end of an ion guide (e.g., ion guide 1202) configured to receive ions. As described herein, the RF voltage waveforms are configured to confine ions within an ion-occupied volume and generate a plurality of migrating pseudopotential wells, which exert a force that biases the ions to move along the axis toward the second end.

[0095] In operation 1404, the controller 1206 may instruct the power supply to apply a first set of DC voltages to a set of first electrodes included in a set of electrodes adjacent to the first end, simultaneously with the application of a set of RF voltage waveforms. As described herein, the first set of DC voltages is configured to generate a first electric field in a first region of the ion guide corresponding to the location of the first set of electrodes. As described herein, the first electric field may be either uniform across the first region or sloped across the first region.

[0096] In operation 1406, the controller 1206 may instruct the power supply to apply a second set of DC voltages to a second set of electrodes included in a set of electrodes and adjacent to the second end, simultaneously with the application of a set of RF voltage waveforms and a first set of DC voltages. As described herein, the second set of DC voltages is configured to generate a second electric field in a second region of the ion guide corresponding to the location of the second set of electrodes. As described herein, the second electric field is uniform across the second region and has an amplitude greater than the maximum amplitude of the first electric field.

[0097] Next, we will describe an example of a controller 1206 that sets the relative lengths of the first and second electric fields.

[0098] Figure 15 shows an electric field graph 1500 illustrating the electric field caused by a power supply 1204 that applies a first set of DC voltages to a first set of electrodes 1504-1 included in electrode 1210 and a second set of DC voltages to a second set of electrodes 1504-2 included in electrode 1210. As shown in the figure, the first set of electrodes 1504-1 is adjacent to the first end 1208-1 of ion guide 1202, and the second set of electrodes 1504-2 is adjacent to the second end 1208-2 of ion guide 1202. On the horizontal axis of the electric field graph 1500, label E1 represents the first electrode included in the series of electrodes 1210 (i.e., the electrode closest to the first end 1208-1), and label En represents the last electrode included in the series of electrodes 1210 (i.e., the electrode closest to the second end 1208-2). The first region of ion guide 1202 corresponds to the location of the first electrode set 1504-1 and is represented in Figure 15 as the space between vertical lines 1506-1 and 1506-2. The second region of ion guide 1202 corresponds to the location of the second electrode set 1504-2 and is represented in Figure 15 as the space between vertical lines 1506-3 and 1506-4.

[0099] A first set of DC voltages is configured to increase according to a quadratic function (e.g., a nonlinear function) across a first set of electrodes 1504-1. This creates a gradient electric field 1508-1 in a first region of the ion guide 1202 corresponding to the locations of the first set of electrodes 1504-1. A second set of DC voltages is configured to increase according to a linear function. This creates a uniform electric field 1508-2 within a second region of the ion guide 1202 corresponding to the locations of the second set of electrodes 1504-2. As used herein, a “uniform” electric field is created by a substantially linear increase in DC voltage across the set of electrodes and may include some slight variations in amplitude that can be caused by several different factors. However, the uniform electric field does not increase across the second set of electrodes 1504-2, unlike the gradient electric field created within a first region associated with the first set of electrodes 1504-1.

[0100] As shown, the amplitude of the uniform electric field 1508-2 (labeled as the electric field intensity along the vertical axis of the electric field graph 1500) is substantially uniform across the second region of ion guide 1202, while the amplitude of the gradient electric field 1508-1 increases across the first region of ion guide 1202. The maximum amplitude of the gradient electric field 1508-1 is located at the position corresponding to the left end of the first region (i.e., the vertical line 1506-2). As shown, the amplitude of the uniform electric field is greater than the maximum amplitude of the gradient electric field 1508-1.

[0101] As depicted in Figure 15, the length of the gradient electric field 1508-1 (with respect to the physical distance between the first end 1208-1 and the second end 1208-2) is relatively greater than the length of the uniform electric field 1508-2. This is because the first electrode set 1504-1 contains more electrodes than the second electrode set 1504-2. Such a configuration is more favorable to charge capacity than ion separation resolution and can be used in situations or experiments where ion separation resolution is relatively unimportant and / or where relatively high charge capacity is desirable.

[0102] Figure 16 is similar to Figure 15, but shows how the electric field graph 1500 changes when controller 1206 specifies a different number of electrodes to be included in the first and second electrode sets 1504-1 and 1504-2. As shown, the length of the uniform electric field 1508-2 is longer compared to the configuration shown in Figure 15. Conversely, the length of the gradient electric field 1508-1 is shorter compared to the configuration shown in Figure 15. This is because controller 1206 specifies relatively more electrodes to be included in the second electrode set 1504-2 than in the configuration in Figure 15, and relatively fewer electrodes to be included in the first electrode set 1504-1 than in the configuration in Figure 15.

[0103] The controller 1206 may specify in any suitable way which electrodes are included in the first and second electrode sets 1504-1 and 1504-2. For example, the controller 1206 may specify which electrodes are included in the first and second electrode sets 1504-1 and 1504-2 by controlling a DC voltage source connected to some or all of the electrodes 1210.

[0104] For illustrative purposes, Figure 17 shows a configuration 1700 in which power supply 1204 includes a plurality of individually controllable DC voltage sources 1706 (e.g., DC voltage sources 1706-1 to 1706-4). Each DC voltage source 1706 is connected to a different electrode included in a set of electrodes 1210 included in ion guide 1202. For illustrative purposes only, ten electrodes labeled E1 to E10 included in the set of electrodes 1210 are shown in Figure 17. As shown, DC voltage source 1706-1 is connected to electrode E1, DC voltage source 1706-2 is connected to electrode E4, DC voltage source 1706-3 is connected to electrode E7, and DC voltage source 1706-4 is connected to electrode E10. In this configuration, DC voltage sources 1706-1 can be individually controlled to output a DC voltage labeled V1 on E1, DC voltage sources 1706-2 can be individually controlled to output a DC voltage labeled V2 on E4, DC voltage sources 1706-3 can be individually controlled to output a DC voltage labeled V3 on E7, and DC voltage sources 1706-4 can be individually controlled to output a DC voltage labeled V4 on E10. Although DC voltage sources 1706 are exemplified in Figure 17 as being directly connected to electrodes E1-E10, it will be recognized that any number of passive components may be present between DC voltage sources 1706 and electrodes E1-E10, which may serve a particular implementation.

[0105] Figure 17 shows DC voltage sources 1706 connected to every four electrodes, but it will be recognized that the DC voltage sources 1706 can be spaced apart by any other suitable number of electrodes included in the series of electrodes 1210. In some examples, the total number of individually controllable DC voltage sources 1706 is less than the total number of electrodes 1210. For example, the DC voltage sources 1706 may be connected to all of the 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, 10th, etc. electrodes included in the series of electrodes 1210. Alternatively, each electrode in the series of electrodes 1210 may have a different DC voltage source 1706 connected to it for finer voltage control.

[0106] As shown, multiple impedance elements 1702-1 to 1702-9 (collectively, "impedance elements 1702") are connected in series with a set of electrodes, with different impedance elements 1702 located between adjacent pairs of electrodes and connected in series with them. For example, impedance element 1702-1 is located between electrodes E1 and E2 and connected in series with them.

[0107] Each impedance element 1702 may be implemented by one or more resistors and / or any other electrical elements having impedance. In some examples, all impedance elements 1702 have the same impedance value (or at least within a relatively small tolerance). Thus, the impedance elements 1702 form a voltage divider circuit that applies different voltage levels to different electrodes included in a set of electrodes 1210. For example, by applying voltage V2 to electrode E4 and voltage V1 to E1, the voltage divider circuit formed by electrodes E2 and E3 can make the voltages at electrodes E2 and E3 a linear interpolation between V1 and V2.

[0108] By setting the DC voltage output by each of the individually controllable DC voltage sources 1706, the controller 1206 can specify which electrodes are included in the first and second electrode sets 1504-1 and 1504-2.

[0109] For illustrative purposes, a series of electrodes 1210 may include 100 electrodes numbered from 1 to 100. Impedance elements may interconnect adjacent electrode pairs as described herein. Eleven individually controllable DC voltage sources 1706 may be connected to 11 of the 100 electrodes. Table 1 below shows exemplary DC voltages applied to these electrodes by the individually controllable DC voltage sources 1706. [Table 1]

[0110] Figure 18 shows graph 1802 illustrating the DC voltage on each electrode of a set of electrodes when the DC voltages in Table 1 are applied to the electrodes shown in Table 1. Figure 18 also shows graph 1804 illustrating the resulting electric field caused by the application of the DC voltage. As shown, the overall electric field has a gradient between electrodes 1-40 and is uniform between electrodes 41-100. This is because the voltage starting at electrode 41 increases linearly, in contrast to the voltage between electrodes 1 and 40, where the voltage increases according to a quadratic function. Thus, in this example, controller 1206 designates electrodes 1-40 as the first set of electrodes 1504-1 and electrodes 41-100 as the second set of electrodes 1504-2. Controller 1206 can adjust this electrode assignment by adjusting one or more of the voltages applied by the individually controllable DC voltage sources 1706.

[0111] Figure 18 also illustrates a scenario in which adjacent regions within the ion guide 1202 may have uniform electric fields of different amplitudes. For example, it is shown that the overall electric field has a gradient between electrodes 1–40, but the electric field in more granular regions (e.g., regions corresponding to electrodes 1–10, 11–20, etc.) is uniform. This may be beneficial for any of the reasons described herein. An example in which the electric fields generated within the first and second regions of the ion guide 1202 are both uniform will be provided here.

[0112] Figure 19 shows an electric field graph 1900 illustrating the electric field caused by a power supply 1204 that applies a first set of DC voltages to a first set of electrodes 1904-1 included in electrode 1210 and a second set of DC voltages to a second set of electrodes 1904-2 included in electrode 1210. As shown in the figure, the first set of electrodes 1904-1 is adjacent to the first end 1208-1 of ion guide 1202, and the second set of electrodes 1904-2 is adjacent to the second end 1208-2 of ion guide 1202. On the horizontal axis of the electric field graph 1900, label E1 represents the first electrode included in the series of electrodes 1210 (i.e., the electrode closest to the first end 1208-1), and label En represents the last electrode included in the series of electrodes 1210 (i.e., the electrode closest to the second end 1208-2). The first region of ion guide 1202 corresponds to the location of the first electrode set 1904-1 and is shown in Figure 19 as the space between vertical lines 1906-1 and 1906-2. The second region of ion guide 1202 corresponds to the location of the second electrode set 1904-2 and is shown in Figure 19 as the space between vertical lines 1906-2 and 1906-3.

[0113] A first set of DC voltages is configured to increase linearly over a first set of electrodes 1904-1. This creates a uniform electric field 1908-1 in a first region of the ion guide 1202 corresponding to the locations of the first set of electrodes 1904-1. A second set of DC voltages is similarly configured to increase linearly. This creates a uniform electric field 1908-2 in a second region of the ion guide 1202 corresponding to the locations of the second set of electrodes 1904-2.

[0114] As shown in the figure, the amplitude of the uniform electric field 1908-2 (labeled as the electric field strength along the vertical axis of the electric field graph 1900) is greater than the amplitude of the uniform electric field 1908-1. In some examples, the amplitude of the second electric field (i.e., the uniform electric field 1908-2) is greater than the amplitude of the first electric field (i.e., the uniform electric field 1908-1) by a predetermined threshold. For example, when it is desirable to trap ions in the range of 200 to 1000 m / z, the amplitude of the second electric field may be set to about 400 volts / meter, and the amplitude of the first electric field may be set to less than or equal to 100 volts / meter, this amplitude depending on the maximum m / z value to be contained. In some operating modes, it may be desirable to increase the amplitude of the second electric field to about 2000 volts / meter.

[0115] As depicted in Figure 19, the length of the uniform electric field 1908-1 (with respect to the physical distance between the first end 1208-1 and the second end 1208-2) is relatively greater than the length of the uniform electric field 1908-2. This is because the first electrode set 1904-1 contains more electrodes than the second electrode set 1904-2. Such a configuration is more favorable to charge capacity than ion separation resolution and can be used in situations or experiments where ion separation resolution is relatively unimportant and / or where relatively high charge capacity is desirable.

[0116] Figure 20 is similar to Figure 19, but shows how the electric field graph 1900 changes when controller 1206 specifies a different number of electrodes to be included in the first and second electrode sets 1904-1 and 1904-2. As shown, the length of the uniform electric field 1908-2 is longer compared to the configuration shown in Figure 19. Conversely, the length of the uniform electric field 1908-1 is shorter compared to the configuration shown in Figure 19. This is because controller 1206 specifies relatively more electrodes to be included in the second electrode set 1904-2 than in the configuration of Figure 19, and relatively fewer electrodes to be included in the first electrode set 1904-1 than in the configuration of Figure 19.

[0117] In some examples, the controller 1206 may determine one or more conditions associated with the analysis of a sample containing ions received by the ion guide 1202, and based on one or more conditions, select which electrodes in the series of electrodes 1210 are included in the first electrode set 1504-1 and which electrodes in the series of electrodes 1210 are included in the second electrode set 1504-2.

[0118] For example, the controller 1206 may identify conditions that are more favorable to the charge capacity of the ion guide than to the ion separation resolution. Based on this, the controller 1206 may select a relatively large number of electrodes to be included in the first set of electrodes 1504-1. In some examples, the controller 1206 may select a relatively large number of electrodes in the set of electrodes 1210 to be included in the first set of electrodes 1504-1 rather than in the second set of electrodes 1504-2, such that the first region having the first electric field is longer than the second region having the second electric field.

[0119] Alternatively, the controller 1206 may identify conditions under which ion separation resolution is preferred over the charge capacitance of the ion guide. Based on this, the controller 1206 may select a relatively large number of electrodes to be included in the second set of electrodes 1504-2. In some examples, the controller 1206 may select a relatively large number of electrodes within the set of electrodes 1210 to be included in the second set of electrodes 1504-2 rather than the first set of electrodes 1504-2, such that the second region having the second electric field is longer than the first region having the first electric field.

[0120] An additional or alternative condition that may be considered by controller 1206 is the operating speed of the ion sorter. For example, a relatively fast instrument may circulate the sorter quickly enough that it never reaches its memory capacity. In this scenario, it may be desirable to maximize the number of separable bins, and therefore the ion separation resolution. Thus, controller 1206 may select a relatively large number of electrodes to include in the second electrode set 1504-2. Alternatively, a relatively slow instrument may have a relatively high filling time, resulting in a relatively small number of separable bins. In this scenario, it may be desirable to prioritize charge separation. Thus, controller 1206 may select a relatively large number of electrodes to include in the first electrode set 1504-1.

[0121] Other conditions that can be determined by the controller 1206 and may affect the number of electrodes designated to be included in the first and second electrode sets 1504-1 and 1504-2 may include user input, one or more attributes of the ions being analyzed, and so on.

[0122] In some examples, the controller 1206 can dynamically adjust which electrodes from the series of electrodes 1210 are included in the first set of electrodes 1504-1 and which electrodes from the series of electrodes 1210 are included in the second set of electrodes 1504-2 during an experiment in which single ion implantation into an ion guide is performed and the ions are m / z separated within the ion guide.

[0123] For example, the controller 1206 may determine that a predetermined time has elapsed during the experiment and, based on this, may assign one or more electrodes initially included in the first electrode set 1504-1 to be included in the second electrode set 1504-2 in order to lengthen the second region having the second electric field. This electrode assignment may be carried out by adjusting the DC voltage supplied by the DC voltage source 1706, as described herein.

[0124] In some examples, the controller 1206 can adjust the electrode assignment to either the first electrode set 1504-1 or the second electrode set 1504-2 based on the stage in the efflux operation during the experiment (e.g., the percentage of accumulated ions effluxed). As described above with respect to Figure 8, the resolution of emitted ions for the electric field configuration in the device in Figure 6D or Figure 15 depends largely on the mass-to-charge ratio. In the first configuration, the second electrode set 1504-2 can provide an acceptable resolution for low m / z ions (e.g., ions with m / z in the range of 200-400 may have a resolution in the range of 10-20), but also has a relatively high charge capacity. As low m / z ions are released from the instrument, the number of ions in the trap decreases, and the charge capacity requirement begins to decrease. At the same time, higher m / z ions begin to elute from the instrument. In this situation, the controller 1206 can adjust the electrode assignment to increase the number of electrodes in the second electrode set 1504-2 (i.e., lengthen the region of the uniform second electric field). While such changes during the experiment have little effect on the charge capacitance (as many ions have already been released), in this example, it can significantly improve the resolution of higher m / z ions (e.g., ions with m / z in the range of 600-900) that are the last to elute from the apparatus.

[0125] In some examples, computer program products embodied in non-temporary computer-readable storage media may be supplied. In such examples, the non-temporary computer-readable storage media may store computer-readable instructions in accordance with the principles described herein. When executed by the processor of a computing device, the instructions may instruct the processor and / or the computing device to perform one or more operations, including one or more of the operations described herein. Such instructions may be stored and / or transmitted using any of a variety of known computer-readable media.

[0126] Non-temporary computer-readable media as used herein may include any non-temporary storage media involved in providing data (e.g., instructions) that can be read and / or executed by a computing device (e.g., by the processor of the computing device). For example, non-temporary computer-readable media may include, but are not limited to, any combination of non-volatile storage media and / or volatile storage media. Exemplary non-volatile storage media include, but are not limited to, read-only memory, flash memory, solid-state drives, magnetic storage devices (e.g., hard disks, floppy disks, magnetic tapes, etc.), ferroelectric random-access memory ("RAM"), and optical discs (e.g., compact discs, digital video discs, Blu-ray discs, etc.). Exemplary volatile storage media include, but are not limited to, RAM (e.g., dynamic RAM).

[0127] Figure 21 shows an exemplary computing device 2100 that may be specifically configured to perform one or more of the operations, methods, and processes described herein. Any of the systems, computing devices, and / or other components described herein may be implemented by the computing device 2100.

[0128] As shown in Figure 21, the computing device 2100 may include a communication interface 2102, a processor 2104, a storage device 2106, and an input / output ("I / O") module 2108, all connected to each other via a communication infrastructure 2110. While an exemplary computing device 2100 is shown in Figure 21, the components illustrated in Figure 21 are not intended to be limiting. Additional or alternative components may be used in other embodiments. The components of the computing device 2100 shown in Figure 21 are described in further detail below.

[0129] The communication interface 2102 may be configured to communicate with one or more computing devices. Examples of the communication interface 2102 include, but are not limited to, wired network interfaces (such as network interface cards), wireless network interfaces (such as wireless network interface cards), modems, audio / video connections, and any other suitable interfaces.

[0130] The processor 2104 generally represents any type or form of processing unit capable of processing data and / or interpreting, executing, and / or directing the execution of one or more of the instructions, processes, and / or operations described herein. The processor 2104 may perform operations by executing computer executable instructions 2112 (e.g., applications, software, code, and / or other executable data instances) stored in the storage device 2106.

[0131] The storage device 2106 may include one or more data storage media, devices, or configurations, and may employ any type, form, and combination of data storage media and / or devices. For example, the storage device 2106 may include, but is not limited to, any combination of non-volatile media and / or volatile media described herein. Electronic data, including the data described herein, may be stored temporarily and / or permanently in the storage device 2106. For example, data representing a computer executable instruction 2112 configured to instruct a processor 2104 to perform any of the operations described herein may be stored in the storage device 2106. In some examples, the data may be located in one or more databases residing within the storage device 2106.

[0132] The I / O module 2108 may include one or more I / O modules configured to receive user input and provide user output. One or more I / O modules may be used to receive input for a single virtual experience. The I / O module 2108 may include any hardware, firmware, software, or combination thereof that supports input and output capabilities. For example, the I / O module 2108 may include, but is not limited to, hardware and / or software for capturing user input, including a keyboard or keypad, a touchscreen component (e.g., a touchscreen display), a receiver (e.g., an RF or infrared receiver), a motion sensor, and / or one or more input buttons.

[0133] The I / O module 2108 may include, but is not limited to, a graphics engine, a display (e.g., a display screen), one or more output drivers (e.g., display drivers), one or more audio speakers, and one or more audio drivers, for presenting output to the user. In a particular embodiment, the I / O module 2108 is configured to provide graphical data to the display for presentation to the user. The graphical data may represent one or more graphical user interfaces and / or any other graphical content, as may be useful for a particular implementation.

[0134] The advantages and features of this disclosure can be further described by the following statement. 1. A system comprising an ion guide configured to receive ions, comprising a first end and a second end, and a series of electrodes positioned between the first end and the second end, wherein the series of electrodes define the ion-occupied volume and the axis of the ion guide between the first end and the second end, and a power supply electrically coupled to the series of electrodes, wherein the power supply applies a set of radio frequency (RF) voltage waveforms to the series of electrodes, the RF voltage waveforms configured to confine ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, the plurality of moving pseudopotential wells exert a force that biases ions to move along the axis toward the second end, and simultaneously with the application of the set of RF voltage waveforms, the first set of electrodes included in the series of electrodes and adjacent to the first end A system comprising: applying a set of direct current (DC) voltages, the first set of DC voltages configured to generate a first electric field in a first region of an ion guide corresponding to the location of a first set of electrodes; and simultaneously with the application of a set of RF voltage waveforms and the first set of DC voltages, applying a second set of DC voltages to a second set of electrodes included in a series of electrodes and adjacent to a second end, the second set of DC voltages configured to generate a second electric field in a second region of an ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field, wherein the first and second electric fields generate a force that biases ions to move along the axis toward the first end. 2. The system as described in Statement 1, further comprising a controller coupled to a power supply, the controller configured to instruct the power supply to apply an RF voltage waveform to a series of electrodes, to apply a first set of DC voltages to a first set of electrodes, and to apply a second set of DC voltages to a second set of electrodes, and to specify which electrodes included in the series of electrodes are included in the first set of electrodes, and which electrodes included in the series of electrodes are included in the second set of electrodes. 3. The system described in any one of the preceding statements, further configured to determine one or more conditions associated with the analysis of an ion-containing sample, and to select, based on one or more conditions, which electrodes in a series of electrodes are included in the first set of electrodes and which electrodes in a series of electrodes are included in the second set of electrodes. 4. Determining one or more conditions associated with the analysis of a sample includes identifying conditions that function favorably to the charge capacity of the ion guide rather than to the ion separation resolution, and selecting a system as described in any one of the preceding statements, which includes selecting relatively more electrodes in a set of electrodes to include in the first set of electrodes rather than in the second set of electrodes, such that the first region having the first electric field is longer than the second region having the second electric field. 5. Determining one or more conditions associated with the analysis of a sample includes identifying conditions that function favorably to ion separation resolution rather than to the charge capacity of the ion guide, and selecting a system as described in any one of the preceding statements, which includes selecting relatively more electrodes in a set of electrodes to include in the second set of electrodes than in the first set of electrodes, such that the second region having the second electric field is longer than the first region having the first electric field. 6. The system described in any one of the preceding statements, further configured to dynamically adjust which electrodes in a series of electrodes are included in the first set of electrodes and which electrodes in a series of electrodes are included in the second set of electrodes during an experiment in which ions are m / z separated within an ion guide. 7. A system as described in any one of the preceding statements, in which dynamic adjustment includes determining that a predetermined amount of time has elapsed during the experiment, and, based on the determination that a predetermined amount of time has elapsed, assigning one or more electrodes initially included in the first set of electrodes to be included in the second set of electrodes in order to lengthen the second region having a second electric field. 8. Further comprising a series of electrodes and a plurality of impedance elements connected in series, wherein different impedance elements among the plurality of impedance elements are located between adjacent electrode pairs included in the series of electrodes and are connected in series with them. The system according to any one of the preceding statements, comprising a plurality of individually controllable DC voltage sources configured to apply first and second sets of DC voltages, each of which is connected to a different electrode included in a set of electrodes, and an impedance element forming a voltage divider circuit that causes different voltage levels to be applied to the different electrodes included in the set of electrodes. 9. A system as described in any one of the preceding statements, in which the total number of individually controllable DC voltage sources included in a set of individually controllable DC voltage sources is less than the total number of electrodes included in a set of electrodes. 10. A system described in any of the preceding statements, in which a gas having a pressure of at least 0.01 Torr is present within the ion-occupied volume. 11. A system as described in any one of the preceding statements, wherein multiple moving pseudopotential wells, a first electric field, and a second electrode field cause one or more of the following: m / z-dependent spatial separation of ions in an ion guide, differential movement of ions in an ion guide, or filtering of ions in an ion guide. 12. The system described in any one of the preceding statements, wherein the first end of the ion guide is an ion inlet and the second end of the ion guide is an ion outlet. 13. The system described in any one of the preceding statements, wherein the first end of the ion guide is an ion outlet and the second end of the ion guide is an ion inlet. 14. A system described in any of the preceding statements, in which the first electric field is uniform across the first region. 15. A system described in any one of the preceding statements, wherein the amplitude of the second electric field is greater than 400 volts / meter and the maximum amplitude of the first electric field is less than 100 volts / meter. 16. The first electric field is a gradient electric field over a first region, as described in any of the preceding statements for the system. 17. A system comprising a memory for storing instructions, and one or more processors communicatively coupled to the memory and configured to execute instructions for performing a process, wherein the process is to instruct a power supply to apply a set of radio frequency (RF) voltage waveforms to a series of electrodes positioned between a first end and a second end of an ion guide, the ion guide being configured to receive ions, the series of electrodes defining an ion-occupied volume and the axis of the ion guide between the first end and the second end, the RF voltage waveforms being configured to confine ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, the plurality of moving pseudopotential wells exerting a force that biases ions to move along the axis toward the second end, and simultaneously with the application of the set of RF voltage waveforms, a first set of electrodes included in the series of electrodes and adjacent to the first end The system includes instructing a power supply to apply a first set of direct current (DC) voltages to a set of electrodes, the first set of DC voltages being configured to generate a first electric field in a first region of an ion guide corresponding to the location of the first set of electrodes, and simultaneously instructing the power supply to apply a second set of DC voltages to a second set of electrodes included in the set of electrodes and adjacent to the second end, the second set of DC voltages being configured to generate a second electric field in a second region of an ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field, wherein the first and second electric fields generate a force that biases ions to move along the axis toward the first end. 18. The system described in Statement 17, further comprising: instructing a power supply to apply an RF voltage waveform to a set of electrodes, a first set of DC voltages to a first set of electrodes, and a second set of DC voltages to a second set of electrodes; specifying which electrodes included in the set of electrodes are included in the first set of electrodes; and specifying which electrodes included in the set of electrodes are included in the second set of electrodes. 19. The system described in statement 17 or 18, further comprising: determining one or more conditions associated with the analysis of an ion-containing sample; and, based on one or more conditions, selecting which electrodes in a series of electrodes are included in the first set of electrodes and which electrodes in a series of electrodes are included in the second set of electrodes. 20. A method comprising instructing a power supply to apply a set of radio frequency (RF) voltage waveforms to a series of electrodes positioned between a first end and a second end of an ion guide, wherein the ion guide is configured to receive ions, the series of electrodes define the ion-occupied volume and the axis of the ion guide between the first end and the second end, and the RF voltage waveforms are configured to confine ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, the plurality of moving pseudopotential wells exert a force that biases ions to move along the axis toward the second end, and simultaneously instructing the power supply to apply a first set of direct current (DC) voltages to a first set of electrodes included in the series of electrodes and adjacent to the first end, while applying the set of RF voltage waveforms. A method comprising: instructing a first set of DC voltages to be configured to generate a first electric field in a first region of an ion guide corresponding to the location of a first set of electrodes; and instructing a power supply to apply a second set of DC voltages to a second set of electrodes included in a set of electrodes and adjacent to a second end, simultaneously with the application of a set of RF voltage waveforms and the first set of DC voltages, wherein the second set of DC voltages is configured to generate a second electric field in a second region of an ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field, wherein the first and second electric fields generate a force that biases ions to move along the axis toward the first end. 21. An exemplary non-transient computer-readable medium, when executed, instructs a power supply to apply a set of radio frequency (RF) voltage waveforms to a set of electrodes positioned between a first end and a second end of an ion guide configured to receive ions, wherein the set of electrodes defines the ion-occupied volume and the axis of the ion guide between the first and second ends, and the RF voltage waveforms are configured to confine ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, which exert a force that biases ions to move along the axis toward the second end, and simultaneously instructs a power supply to apply a first set of DC voltages to a set of first electrodes included in the set of electrodes and adjacent to the first end. A non-temporary computer-readable medium stores instructions to perform a process including: indicating that a set of first DC voltages is configured to generate a first electric field in a first region of an ion guide corresponding to the location of a set of first electrodes; and simultaneously with the application of a set of RF voltage waveforms and a set of first DC voltages, instructing a power supply to apply a second set of DC voltages to a second set of electrodes included in a set of electrodes and adjacent to a second end, wherein the set of second DC voltages is configured to generate a second electric field in a second region of an ion guide corresponding to the location of a set of second electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field, wherein the first and second electric fields generate a force that biases ions to move along the axis toward the first end.

[0135] In the above description, various exemplary embodiments have been described with reference to the accompanying drawings. However, it will be apparent that various modifications and changes can be made thereto, and additional embodiments can be realized, without departing from the scope of the invention as described in the following claims. For example, certain features of one embodiment described herein can be combined with or replaced by features of another embodiment described herein. Therefore, this specification and the drawings should be considered in an exemplary sense, not in an restrictive sense.

Claims

1. It is a system, An ion guide configured to receive ions, The first end and, The second end and The device comprises a series of electrodes positioned between the first end and the second end, wherein the series of electrodes define the ion-occupied volume and the axis of the ion guide between the first end and the second end, The system comprises a power supply electrically coupled to the series of electrodes, and the power supply is The method involves applying a set of high-frequency (RF) voltage waveforms to the series of electrodes, wherein the RF voltage waveforms are configured to confine the ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, and the plurality of moving pseudopotential wells exert a force that biases the ions to move along the axis toward the second end. Simultaneously with the application of the set of RF voltage waveforms, a first set of direct current (DC) voltages is applied to a set of first electrodes included in the series of electrodes and adjacent to the first end, wherein the first set of DC voltages is configured to generate a first electric field within a first region of the ion guide corresponding to the location of the set of first electrodes. Simultaneously with the application of the RF voltage waveform set and the first DC voltage set, a second DC voltage set is applied to a second set of electrodes included in the series of electrodes and adjacent to the second end, wherein the second DC voltage set is configured to generate a second electric field in a second region of the ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field. A system in which the first electric field and the second electric field generate a force that biases the ion to move along the axis toward the first end.

2. The power supply is further coupled to a controller, and the controller is The power supply is instructed to apply the RF voltage waveform to the series of electrodes, to apply the first set of DC voltages to the first set of electrodes, and to apply the second set of DC voltages to the second set of electrodes. Specify which of the series of electrodes is included in the first set of electrodes, The system according to claim 1, configured to specify which electrodes included in the series of electrodes are included in the second set of electrodes.

3. The aforementioned controller, Determine one or more conditions associated with the analysis of the sample containing the aforementioned ions, The system according to claim 2, further configured to select which electrodes included in the series of electrodes are included in the first set of electrodes and which electrodes included in the series of electrodes are included in the second set of electrodes, based on one or more of the conditions.

4. Determining one or more conditions associated with the analysis of the sample includes identifying conditions that function more favorably to the charge capacity of the ion guide than to the ion separation resolution, The system according to claim 3, wherein the selection includes selecting relatively more electrodes in the set of electrodes to be included in the first set of electrodes than in the second set of electrodes, such that the first region having the first electric field is longer than the second region having the second electric field.

5. Determining one or more conditions associated with the analysis of the sample includes identifying conditions that function more favorably to ion separation resolution than to the charge capacity of the ion guide, The system according to claim 3, wherein the selection includes selecting relatively more electrodes in the set of electrodes to be included in the second set of electrodes than in the first set of electrodes, such that the second region having the second electric field is longer than the first region having the first electric field.

6. The system according to claim 2, wherein the controller is further configured to dynamically adjust which electrodes in the series of electrodes are included in the first set of electrodes and which electrodes in the series of electrodes are included in the second set of electrodes during an experiment in which the ions are m / z separated in the ion guide.

7. The aforementioned dynamic adjustment is Determining that a predetermined amount of time has elapsed during the aforementioned experiment, The system according to claim 6, comprising, based on the determination that a predetermined amount of time has elapsed, assigning one or more electrodes initially included in the set of first electrodes to be included in the set of second electrodes in order to lengthen the second region having the second electric field.

8. The series of electrodes is further comprising a plurality of impedance elements connected in series, wherein different impedance elements among the plurality of impedance elements are located between adjacent electrode pairs included in the series of electrodes and are connected in series with them. The power supply comprises a plurality of individually controllable DC voltage sources configured to apply the first and second sets of DC voltages, each of the individually controllable DC voltage sources being connected to a different electrode included in the series of electrodes, The system according to claim 2, wherein the impedance element forms a voltage divider circuit that applies different voltage levels to different electrodes included in the series of electrodes.

9. The system according to claim 8, wherein the total number of individually controllable DC voltage sources included in the plurality of individually controllable DC voltage sources is less than the total number of electrodes included in the series of electrodes.

10. The system according to claim 1, wherein a gas having a pressure of at least 0.01 Torr is contained within the ion-occupied volume.

11. The system according to claim 1, wherein the plurality of moving pseudopotential wells, the first electric field, and the second electric field cause one or more of the following: m / z-dependent spatial separation of the ions in the ion guide, differential movement of the ions in the ion guide, or filtering of the ions in the ion guide.

12. The system according to claim 1, wherein the first end of the ion guide is an ion inlet, and the second end of the ion guide is an ion outlet.

13. The system according to claim 1, wherein the first end of the ion guide is an ion outlet, and the second end of the ion guide is an ion inlet.

14. The system according to claim 1, wherein the first electric field is uniform across the first region.

15. The amplitude of the second electric field is greater than 400 volts / meter. The system according to claim 14, wherein the maximum amplitude of the first electric field is less than 100 volts / meter.

16. The system according to claim 1, wherein the first electric field is a gradient electric field over the first region.

17. It is a system, Memory for storing instructions, The process comprises one or more processors, which are communicably coupled to the memory and configured to execute the instructions for carrying out the process, and the process The power supply is instructed to apply a set of radio frequency (RF) voltage waveforms to a series of electrodes positioned between a first end and a second end of an ion guide, wherein the ion guide is configured to receive ions, the series of electrodes define the ion-occupied volume and the axis of the ion guide between the first and second ends, and the RF voltage waveforms are configured to confine the ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, the plurality of moving pseudopotential wells exert a force that biases the ions to move along the axis toward the second end. The power supply is instructed to apply a first set of direct current (DC) voltages to a first set of electrodes included in the series of electrodes and adjacent to the first end, simultaneously with the application of the set of RF voltage waveforms, wherein the set of DC voltages is configured to generate a first electric field within a first region of the ion guide corresponding to the location of the first set of electrodes. The power supply is instructed to apply a second set of DC voltages to a second set of electrodes included in the series of electrodes and adjacent to the second end, simultaneously with the application of the set of RF voltage waveforms and the first set of DC voltages, wherein the second set of DC voltages is configured to generate a second electric field in a second region of the ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field. A system in which the first electric field and the second electric field generate a force that biases the ion to move along the axis toward the first end.

18. The aforementioned process, The power supply is instructed to apply the RF voltage waveform to the series of electrodes, the first DC voltage set to the first set of electrodes, and the second DC voltage set to the second set of electrodes. Specify which of the series of electrodes is included in the first set of electrodes, The system according to claim 17, further comprising specifying which electrodes included in the series of electrodes are included in the second set of electrodes.

19. The aforementioned process, To determine one or more conditions associated with the analysis of a sample containing the aforementioned ions, The system according to claim 18, further comprising selecting, based on one or more of the above conditions, which electrodes included in the series of electrodes are included in the first set of electrodes and which electrodes included in the series of electrodes are included in the second set of electrodes.

20. It is a method, The power supply is instructed to apply a set of radio frequency (RF) voltage waveforms to a series of electrodes positioned between a first end and a second end of an ion guide, wherein the ion guide is configured to receive ions, the series of electrodes define the ion-occupied volume and the axis of the ion guide between the first and second ends, and the RF voltage waveforms are configured to confine the ions within the ion-occupied volume and generate a plurality of moving pseudopotential wells, the plurality of moving pseudopotential wells exert a force that biases the ions to move along the axis toward the second end. The power supply is instructed to apply a first set of direct current (DC) voltages to a first set of electrodes included in the series of electrodes and adjacent to the first end, simultaneously with the application of the set of RF voltage waveforms, wherein the set of DC voltages is configured to generate a first electric field within a first region of the ion guide corresponding to the location of the first set of electrodes. The power supply is instructed to apply a second set of DC voltages to a second set of electrodes included in the series of electrodes and adjacent to the second end, simultaneously with the application of the set of RF voltage waveforms and the first set of DC voltages, wherein the second set of DC voltages is configured to generate a second electric field in a second region of the ion guide corresponding to the location of the second set of electrodes, the second electric field being uniform across the second region and having an amplitude greater than the maximum amplitude of the first electric field. A method wherein the first electric field and the second electric field generate a force that biases the ion to move along the axis toward the first end.

Images