Apparatus and method for transmitting and focusing ions

Abstract

The invention relates to a radio frequency device for transmitting, focusing and confining ions, in particular mass spectrometry and ion mobility spectrometry. An apparatus for transmitting and focusing ions, comprising an ion source, a surface provided with an array of radio frequency electrodes, and at least one electrode disposed opposite the surface and forming an ion transmission channel together, the at least one electrode having at least one direct current potential, and the surface with the radio frequency electrode array is arranged along the ion transmission channel. A method for transmitting and focusing ions is also described. The technical result consists in improving the efficiency of ion transport and focusing, preventing dispersion of ion packets during transport through the device, eliminating loss of resolution, and enabling the device to resist contaminants, thereby providing stable operation of the transport device and overall stability characteristics of a mass spectrometer or ion mobility spectrometer under high load and continuous analysis conditions.

Description

Technical Field

[0001] The present invention relates to radio frequency devices for transporting, focusing and retaining ions, and in particular to mass spectrometry and ion mobility spectrometry. Background Art

[0002] A mass spectrometer typically consists of an ion source, a vacuum chamber, a mass analyzer, and an ion detector. The ions generated in the ion source enter the mass analyzer, where they are separated according to their mass-to-charge ratio (hereinafter referred to as "mass") and then recorded by the detector. If the ion source operates at a higher pressure, a system is required to transport the ions to a vacuum chamber with a typical pressure of 1E-5-1E-6 Torr, where the ions are separated by mass in the mass analyzer. This type of device is called a differential pumping interface, in which the pressure gradient is divided into several chamber segments. Each chamber is separated from the next chamber by a diaphragm, which limits the flow of gas into the next chamber. At the same time, to avoid loss of analytical sensitivity, the ions need to be focused before entering the next stage.

[0003] In addition to minimizing ion loss, the differential pumping interface and other transport systems also require long-term stability. This includes resistance to contaminants that enter the vacuum chamber along with the ions. Contaminants include low-volatility substances or compounds that can form stable films on the electrode surfaces. When the mass analyzer is coupled to a device that pre-separates the ions according to certain parameters, such as high-speed chromatography or ion mobility spectrometry (IMS), which separates sample components at high speeds of 10-1000 milliseconds, or when measuring fast processes, additional requirements are placed on the operating speed of the focusing and transport systems to avoid losing the resolution achieved by the previous separation stage.

[0004] Currently, a range of systems are in use that can focus and transport ions in gases. The most common of these are: ion funnels, radiofrequency multipoles (quadrupoles, hexapole, octopole, etc.), and devices with "traveling wave" fields. Radiofrequency multipoles are the most widely used ion transport devices. Their working principle is to form an axial channel along which ions move. In the radial direction, the movement of ions is restricted by a pseudopotential well. Under vacuum conditions, for m rods, this pseudopotential well is usually expressed as:

[0005]

[0006] Where m is the number of rods, V rf is the amplitude of the RF voltage, R is the radius of the ion's position in the multipole, ω is the angular frequency of the RF power supply, M is the mass of the ion, and r ois the inscribed circle radius of the multipole rods. In the presence of gas, ions with kinetic energy greater than that of gas molecules or atoms lose their kinetic energy through collisions with the gas. During this process, the ions cool, and the ion beam becomes focused. This feature significantly improves ion transmission efficiency and has been patented (Douglas DJ, French J.B. Patent US4963736B1, 1989).

[0007] The ion funnel is one of the classic methods for implementing a system for transporting and focusing ions. It is an array consisting of multiple electrodes with coaxial holes. From the mass spectrometer exit toward the analyzer, the aperture of each subsequent electrode is smaller than that of the previous one, forming a space for ion movement, namely a funnel (US6107628A, 22.08.2000, US8299443B1, 30.10.2012). A radio frequency (RF) voltage is applied to the electrode, and a voltage with opposite phase is applied to the adjacent electrode. The RF field pushes the ions toward the axis of the device. At the same time, a constant direct current (DC) voltage is applied to the electrode to establish an electric field gradient along the axis, pushing the ions toward the exit diaphragm. In this process, the ion beam is spatially compressed, and the ions are focused and enter the next stage.

[0008] Because ions need to be transported from the high-pressure region to the low-pressure region, it is preferable to reduce the aperture of the outlet diaphragm to reduce the load on the vacuum pump. However, in this case, the ions have difficulty passing through the area in front of the diaphragm due to the trap created by the RF field. Because the pseudopotential eigenvalue that pushes ions toward the center of the trap is proportional to the electrode spacing, according to the known formula for calculating the pseudopotential of a ring electrode [Mass Spectrometry Reviews, 2010, 29, 294-312]:

[0009]

[0010] where r and z are the radial and axial components, respectively, δ = d / π, z = d(i + 1 / 2), i is the electrode number, d is the distance between adjacent electrodes, ρ is the aperture radius of the first electrode, I0 and I1 are the 0th and 1st order modified Bessel functions, respectively, and V rf is the amplitude of the RF field.

[0011] According to these equations, in the constricted section of the ion funnel, the pseudopotential may "close" at the funnel outlet, hindering the escape of ions. This effect hinders the transport of ions through small-pore diaphragms, while using a large-pore outlet diaphragm increases the gas load on the subsequent pumping stage.

[0012] Another common device for transporting and focusing ions involves achieving ion motion in a traveling wave (TW) field. Typically, this type of ion transport device consists of a series of annular electrode arrays with constant apertures (US7375344B2, May 20, 2008, US6693276B2, February 17, 2004, US6794641B22002Micromass). In these proposed systems, a slowly varying DC voltage mixed with a higher-frequency RF component is applied to the electrodes. RF voltages of opposite phases are applied to pairs of adjacent electrodes, while an AC voltage with a phase shift of 360° / N (where N is the number of electrodes in the group) is applied to groups of four or more electrodes. This creates a traveling wave voltage field that propels ions over the surfaces of the RF electrodes.

[0013] Another subsystem for transporting, focusing, and separating ions—Structures for Lossless Ion Manipulations (SLIM)—is described in multiple patents (US8969800B1, March 3, 2015, US9704701B2, November 7, 2017, and US9966244B2, August 5, 2018, Battelle Memorial Institute). Its electrode structure consists of an array of electrodes on two adjacent surfaces. An RF voltage is applied to one set of electrodes to confine the ions between the electrodes. To achieve this, RF voltages with a 180-degree phase shift are applied to adjacent electrodes. A slowly varying DC voltage is applied to another set of electrodes to transport and / or separate the ions based on their mobility.

[0014] A common drawback of the aforementioned devices is their inadequate resistance to contaminants deposited on the field-forming electrodes. The gas stream entering from the ion source along with the ions may contain low-volatility neutral contaminant particles. Even if the ions are effectively reflected and transmitted by the electrode surface, these particles will still deposit on the surface and may distort the electric field of the focused ions and become a source of increased instrument background noise. This situation is exacerbated when analyzing samples with complex matrices, such as plasma or petroleum samples, or when the analysis is performed in continuous day and night mode.

[0015] Furthermore, the device proposed by the present invention overcomes the disadvantage of the "ion funnel" type device, namely the difficulty in using a small aperture outlet membrane. The disclosed device is capable of focusing and transmitting ions through a small aperture membrane.

[0016] The ion transport and focusing devices disclosed herein provide a unique combination of properties that make them more suitable for transporting ions over a wide pressure range. Summary of the Invention

[0017] The technical problem to be solved by the present invention is to create an ion transmission and focusing device and method that has high efficiency (i.e., minimal loss), can prevent ion packets from becoming blurred over time during transmission, and can resist contaminants that enter the transmission and focusing device along with the ions.

[0018] The technical effects are: improving the efficiency of ion transmission and focusing, preventing the ion packets from blurring over time during transmission through the device and avoiding resolution loss, and the device to be protected has anti-pollution capabilities, thereby ensuring the stability of the transmission device and the stability of the entire mass spectrometer or IMS (ion mobility spectrometer) characteristics under high instrument load and continuous analysis conditions.

[0019] The technical effect is achieved in the following manner: a device for transporting and focusing ions, comprising an ion source, a surface provided with a radio frequency electrode array, and at least one electrode arranged opposite to the surface and together constituting an ion transport channel, wherein at least one electrode is applied with at least one DC potential, and the surface with the radio frequency electrode array is arranged along the ion transport channel.

[0020] In addition, the radio frequency electrode array has a repeating pattern and is composed of a plurality of electrode groups, each group having N electrodes repeated along a tangential direction.

[0021] In addition, the RF electrode array and the DC electrode arranged opposite to the RF electrode array gradually narrow toward the device outlet, thereby compressing the ion packets in two directions: perpendicular to the surface (Y axis) and along the lateral direction of the device (X axis).

[0022] Furthermore, the size of the pattern and the pattern itself may vary along the tangential direction.

[0023] Furthermore, the apparatus is configured to apply N time-varying potentials to a plurality of electrode groups, each group consisting of N electrodes of the radio frequency electrode array.

[0024] In addition, N alternating current voltages are applied to a plurality of electrode groups of N electrodes of the radio frequency electrode array, and their phases are shifted by at least 2π / N relative to adjacent electrodes in the group.

[0025] Furthermore, the apparatus is configured to apply RF voltages with a phase difference of π to adjacent electrodes in the RF electrode array.

[0026] In addition, at least a portion of the electrodes in the electrode array are in the shape of a rectangle, an angular curved strip, or a curved strip with a portion of an ellipse or a portion of a ring.

[0027] In addition, the radio frequency electrode array has a flat insulating substrate and can be implemented by printed circuit board technology.

[0028] In addition, in addition to the RF electrode array, the surface further includes at least one or more electrodes with a DC potential applied thereto disposed at the edge of the surface to form a constant electric field or RF electric field that guides ions toward the central axis of the ion transport channel.

[0029] In addition, the electrodes with DC potential disposed opposite to the radio frequency electrode array are made into a plate-shaped, grid-shaped or other linear structures.

[0030] In addition, the outlet of the device is also connected to a downstream device, which is composed of similar radio frequency electrode arrays arranged opposite to each other. These arrays form similar traveling wave fields for confining ions in the ion transmission channel and transporting them along the channel.

[0031] In addition, the outlet of the device can be connected to the outlet of the device at 10 -9 For use with ion sources operating in the gas pressure range from 1000 Torr to 1000 Torr.

[0032] A method for ion transport and focusing is implemented by an apparatus comprising an ion source, a surface provided with a radio frequency electrode array and arranged along an ion transport channel, and at least one electrode disposed opposite the surface and together forming the ion transport channel, wherein at least one DC potential is applied to the electrode, the method comprising the following steps:

[0033] directing a stream of gaseous ions from an ion source to a space between a surface having an array of radio frequency electrodes and an electrode having a DC potential;

[0034] forming an electric field that draws ions from at least one electrode with a DC potential toward a surface with a radio frequency electrode array;

[0035] An electric field is formed that pushes ions away from the surface and guides them into an ion transport channel formed between the electrode array and at least one electrode with a DC potential, where the ions are confined and move toward an outlet of the device.

[0036] In addition, the movement of ions along the axial direction toward the device outlet is achieved by applying a power supply voltage to the electrode array to form a traveling wave electric field.

[0037] Furthermore, the movement of ions towards the device outlet is achieved by applying a neutral gas flow from the ion source in the axial direction.

[0038] In addition, the movement of ions toward the device outlet is achieved by the axial traveling wave field formed by the electrode group.

[0039] Furthermore, the gaseous ion flow is directed along an axis that is inclined relative to the surface carrying the electrode array, so that a substantial portion of neutral components including pollutants are not deposited on said electrode array and inlet portions of downstream devices.

[0040] Furthermore, to form a traveling wave electric field, a time-varying voltage is applied to alternating electrode groups with a phase shift relative to adjacent electrode groups.

[0041] Furthermore, within each electrode group, from the first electrode to the last electrode in the ion migration direction, the voltage phases on adjacent electrodes are shifted to form potential peaks and potential valleys that move in the tangential direction.

[0042] In addition, the power supply is applied in such a way that an inverted signal with a higher frequency is applied to adjacent electrodes, and another signal with a different frequency is superimposed on this signal, wherein the frequency of the superimposed signal is several times lower than that of the first signal, and has a phase shift relative to the adjacent electrodes in the group, and is distributed to the respective electrode groups.

[0043] In addition, the power supply voltage is a sine signal, a rectangular wave, a triangle wave or a sawtooth waveform.

[0044] Furthermore, the supply voltage is varied depending on the operating mode of the device, in particular the accumulation mode or the ion transport mode, by alternating these modes ion packets of the desired duration can be formed.

[0045] Additionally, in accumulation mode, power is applied to the electrode array in such a way that ions are not deposited on the device surface, but also do not enter downstream devices.

[0046] In addition, in the ion transmission mode, an RF voltage is applied to the electrode array to guide ions toward a traveling wave field at the device outlet, or other guiding electric fields with a DC component are formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 - an overall view of a preferred embodiment of the apparatus for transporting and focusing ions;

[0048] Figure 2 - a side view of a preferred embodiment of the apparatus for transporting and focusing ions;

[0049] Figure 3 - XY plane view of a preferred embodiment of the device for transporting and focusing ions along section AA;

[0050] Figure 4 - a top view (XZ plane) of a preferred embodiment of the device for transporting and focusing ions;

[0051] Figure 5- The trajectories of ions in the device used to transport and focus the ions. DETAILED DESCRIPTION

[0052] The claimed solution aims to provide an apparatus and method for transporting, focusing and trapping ions using electric fields with minimal ion losses over a wide pressure range.

[0053] The main fields of application of the disclosed device (ion focusing device) are differential pumping interfaces and inlet or outlet stages of devices for ion separation based on ion properties (eg based on mobility, M / z ratio).

[0054] Figure 1-5 A preferred embodiment of an apparatus (10) for transporting and focusing ions is shown, comprising an ion source (1), wherein an ion flow (4) with a gas flow emitted from the ion source enters a space formed by a surface (6) with a plurality of radio frequency (RF) field-forming electrode groups (2) and a DC electrode (3), which together form a channel (5) for ion movement. The electrode (3) generates an electric field that guides ions toward the electrode group (2). A mixed signal of RF and DC voltage is applied to the surface (6) with the plurality of RF field-forming electrodes (2) to form a field that pushes ions away from the surface and guides them into the space between the electrode group (2) and the electrode (3). Under the action of the field formed by the electrode group (2) and the electrode (3), an ion transport channel (5) is formed, and the ions are confined in the channel and move along the Z axis toward the outlet of the ion focusing apparatus (10). In the preferred embodiment, the movement of ions along the Z-axis is achieved by a traveling wave electric field, which guides the ions along the ion transport channel (5) from the inlet end to the outlet end of the ion focusing device (10). The term "RF electrode" does not limit the power supply mode of the electrode (2) to only RF voltage.

[0055] In addition, the movement of ions along the Z-axis direction can also be achieved by a neutral gas flow entering from the source (1) along the Z-axis direction.

[0056] In addition, the movement of ions along the Z-axis direction can also be achieved by the DC electric field component formed by the electrode group (2) along the Z-axis direction, which is similar to the formation of the field in a classic ion funnel.

[0057] A downstream device (8) may be provided at the outlet of the ion focusing device (10), which receives ions from the device (10) so as to further transmit them to a subsequent stage of the interface or an ion separation device.

[0058] The gaseous ion stream (4) may contain neutral particles (7), including carrier gas molecules, volatile and low-volatility pollutant particles. In a preferred embodiment, the gaseous ion stream (4) is guided along an axis that is inclined relative to the surface (6) with the electrode group (2), so that the main part of the neutral components (7), including pollutants, does not fall on the electrode (2) and the inlet part of the downstream device (8) located after the ion focusing device (10). Unlike the above-mentioned prior art, during the particle transmission process, the gas jet is guided to bypass the electrodes for focusing and guiding the ions, thereby eliminating contamination of the electrodes by pollutants, thereby ensuring that the ions can be continuously and effectively transmitted to the device outlet.

[0059] At the same time, the gas flow (4) can be directed towards the gas pumping device (9). By directing the gas flow towards the pump, more efficient pumping is achieved, thereby reducing the pressure in the chamber where the ion focusing device (10) is located.

[0060] The ion source (1) can be a preceding stage of a differential pumping interface, a device for separating ions according to their characteristics, or any ion source operating at near atmospheric pressure, fore vacuum, or high vacuum pressure.

[0061] In a preferred embodiment, each electrode in the plurality of RF electrodes (2) is rectangular and separated by an insulator, and the plurality of RF electrodes (2) has a periodically repeating pattern and is composed of 2, 3, 4, 5 or more electrodes per group. In the most common embodiment, the plurality of RF electrode arrays are divided into a plurality of groups of 4 electrodes each to generate a traveling wave field.

[0062] The RF electrode array (2) and its corresponding DC electrode (3) can be retracted toward the outlet, thereby compressing the ion packets in two directions: perpendicular to the surface (Y-axis) and transverse to the device (X-axis), thereby forming an ion flow moving along the channel.

[0063] According to a preferred embodiment, the repeating pattern of field forming electrodes (2) extends over a substantial area of the surface (6).

[0064] The size of the electrodes and the distance between them can be varied according to the electric field requirements under different ion transmission conditions. The distance between the electrodes is usually selected based on the condition of reducing the probability of electrical breakdown. In a typical example, when the ion focusing device is at 10 -9When working under a pressure of 100 torr, the spacing between the electrodes is about 0.1-1 mm, or even greater than 1 mm, and the gap between the electrodes is 0.05 to 1 mm, or even greater than 1 mm. When the pressure is increased to atmospheric pressure, in order to maintain the repulsive effect of the pseudopotential field on ions above the surface, it is preferred to reduce the electrode spacing to 5-10 microns (Poteshin, S. et al., EjMS, 2020, 26(4), pp. 274-280). On the other hand, under this pressure, a larger electrode spacing of 1-5 mm in the structure can achieve a more efficient traveling wave field, thereby transmitting ions along the tangential direction.

[0065] In one embodiment, the shape of the single electrode (2) can be a sector, an angle, or other curved shape with its center on the axis of the surface (2) in addition to being rectangular. The diameter or characteristic dimension of the curved electrode can change toward the outlet of the device (10). In this case, the traveling wave field will additionally guide ions from the peripheral region toward the central axis of the device.

[0066] In one embodiment, the size of the repeating pattern can vary along the tangential direction (6). For example, at the entrance of the ion focusing device, the size of the pattern can be about 1.2-5 times or more larger than the size of the pattern at the exit. Varying the size of the pattern can adjust the effective effect of the traveling wave field on the ions, because the characteristic action distance of the traveling wave field above the electrode surface decays exponentially, where the repetitive spacing of the electrode pattern is at a power of the exponent. Therefore, as the size of the pattern increases, the distance above the surface over which the repulsive field of the traveling wave field and the pseudopotential field acts also increases.

[0067] In one embodiment, the ion source can be a differential pumping interface or the preceding stage of an ion characteristic separator, or any ion source operating at near atmospheric pressure, fore-vacuum, or high vacuum pressure.

[0068] The ion transmission and focusing method is implemented by the above-mentioned device, which includes an ion source, a surface provided with a radio frequency electrode array and arranged along an ion transmission channel, and at least one electrode arranged opposite to the surface and jointly forming the ion transmission channel, wherein at least one DC potential is applied to the electrode. The method comprises the following steps:

[0069] - directing a stream of gaseous ions from an ion source to a space between a surface having an array of radio frequency electrodes and an electrode having a DC potential;

[0070] - forming an electric field that draws ions from at least one electrode with a DC potential toward a surface with an array of radiofrequency electrodes;

[0071] - forming an electric field that pushes ions away from the surface and guides them into an ion transport channel formed between the electrode array and at least one electrode with a DC potential, where the ions are confined and move toward the outlet of the device.

[0072] The power supply of the electrodes can be varied according to the requirements of the electric field under different ion transport conditions. In a preferred embodiment, the power supply is applied to the electrodes (2) in such a way that a traveling wave field is generated above the electrode surface, i.e., a field with alternating potential maxima and minima that moves along the surface above the electrodes is generated. In order to form a traveling wave electric field, a time-varying voltage with a phase shift relative to the adjacent electrode groups is applied to the alternating electrode groups. Within each electrode group, from the first electrode to the last electrode in the direction of ion movement, the voltage phases on the adjacent electrodes are shifted to form potential peaks and valleys that move along the tangential direction. In the classical case, the phase shift value is selected as 360 / n, where n is the number of electrodes in the group. Therefore, in a group, the first electrode is maintained at the first voltage value, the second electrode at the second voltage value, and so on. At the same time, at a first moment t1, the first voltage is applied to the first electrode of all groups, the second voltage is applied to the second electrode of all groups, and so on. At a second moment t2, the first voltage is applied to the second electrode of each group, the second voltage is applied to the third electrode of each group, and so on. In this way, the driving field above the electrode is "stepped" in the direction of ion movement, thereby generating a traveling wave. The ion focusing device can contain 2 or more groups, and each group can include 4, 5, 6 or more electrodes.

[0073] The traveling wave creates peaks and valleys in the potential. The wave propagates along the plate in the direction of the desired ion movement. Depending on the ratio of the ion velocity to the traveling wave's velocity, two types of ion motion are possible. If the ions have very high mobility, they move with the wave. In this case, the ion's velocity equals that of the traveling wave. If the ions are carried along by the potential wave, they "coast" on the "wave crests," resulting in a velocity that falls below the wave speed. In this case, the ions will move along the channel at different speeds within the wave field, depending on their mobility. Ions with higher mobility will move with the wave most of the time, while ions with lower mobility will "jump over" the wave crests more frequently. The more ions "jump over" the wave crests, the slower they move through the device.

[0074] In one embodiment, the power supply voltage applied to the electrode group can be a sum of voltages with different frequencies, phases, and amplitudes. In a preferred embodiment, the power supply is provided as follows: a higher frequency (e.g., 0.5-10 MHz) anti-phase signal is applied to adjacent electrodes, and a lower frequency (preferably 2-10 times lower than the first frequency) and a phase shifted signal relative to adjacent electrodes in the group are superimposed on this signal, and the signal is distributed to the electrode group.

[0075] The power supply voltage can be a sine signal, a rectangular wave, a triangle wave, a sawtooth wave or other waveforms.

[0076] The power supply voltage can be changed according to the operating mode of the ion focusing device. Two main operating modes of the device can be distinguished - accumulation mode and ion transmission mode. In accumulation mode, power is applied to the electrode group (2) in such a way that ions are not deposited on the surface of the device (10), but also do not enter the downstream device (8). In one embodiment, to achieve this mode, the voltage applied to the electrodes only forms a field that confines the ions above the surface, without generating a field that pushes the ions towards the device outlet. At the same time, a cutoff potential is applied to one end electrode of the device (10) or its outlet diaphragm (not shown in the figure) to prevent ions from leaving the device (10). For example, only RF voltages with opposite phases are applied to adjacent electrodes. In order to achieve the ion transmission mode, RF voltages that form a traveling wave field are applied to the electrodes to guide the ions towards the outlet of the device (10), or other guiding fields are applied, such as a field with a DC component similar to the classical ion funnel field. Alternating the above modes can form ion packets of the desired duration.

[0077] The DC electrodes (3) in the device (10) are used to form a field that guides ions to the surface of the electrode group (2). The characteristic attenuation distance of the traveling wave field above the surface is approximately the repetition spacing of the electrode group. Therefore, the effective movement of ions along the surface only occurs near the surface. In order to push the ions to move along the surface in the Z direction toward the outlet of the device (10), it is necessary to make the ions close to the surface of the RF electrode group (2). To this end, in a preferred embodiment, one or more electrodes with a constant voltage are set above the surface with the RF electrode group (2), which form a field that guides ions to the surface of the RF electrode group (2). The electrode (3) can be a conductive plate, a mesh or a row of wires. In a preferred embodiment, in order to prevent the electrode from being contaminated by the deposition of neutral components with low volatility substances entering from the source (1), the electrode (3) is composed of several wires. The shape of the electrode (3) should be selected so that a pushing field is generated at least at the outlet portion of the surface of the electrode group (2). The shape of the electrode (3) can be bent along the X-axis to generate a field that guides ions to the central part of the ion movement channel (5), closer to the axis of the device. A potential is applied to the wire to set the pushing field.

[0078] In one embodiment, the gaseous ion flow (4) may enter along an axis parallel to the tangential direction (6).

[0079] In one embodiment, the surface (6) may be absent, and the electrode group may be composed of a plurality of wires, both ends of which are fixed to non-conductive or weakly conductive materials.

[0080] According to a preferred embodiment of the ion focusing device, which is used for focusing and transmitting ions at near atmospheric pressure (for example, when it is used in conjunction with an ion source operating at atmospheric pressure, such as ESI, APCI, etc.), the configuration of the ion focusing device is adjusted to minimize the probability of electrical breakdown. In order to achieve effective focusing of ions and transmission to the device outlet at high pressure, it is necessary to apply a large voltage amplitude to the electrode group (2) to form the required traveling wave field. In this case, the electrode group (2) is preferably implemented in the form of a wire. The wire is fixed on an insulator resistant to electrical breakdown. The diameter of the wire and the distance between them can be changed according to the requirements for the electric field. For example, the wire diameter can be 0.02-2 mm or larger. The distance between the wires should be selected to be sufficient to reduce the probability of electrical breakdown between them, and can be 0.1-5 mm or 5-15 mm. In a typical example, the wire diameter is 0.5 mm, the distance between them is 2 mm, and the RF voltage amplitude Vpp on the electrode is about 3 kV.

[0081] In one embodiment, in addition to the RF electrode group, the surface (6) can also be provided with electrodes (11) on the side portion, such as Figure 5 shown.

[0082] The claimed apparatus and method ensure that:

[0083] - Highly efficient ion transmission with minimal losses. This ensures high sensitivity with short data acquisition times, which is crucial for measuring fast processes or small sample volumes.

[0084] - Preventing the temporal blurring of ion packets as they are transported through the device. This avoids the loss of resolution achieved in previous separation stages (e.g., gas chromatography (GC), liquid chromatography (LC), IMS (ion mobility spectrometry)). The claimed transport and focusing device and method ensure that the characteristic blurring time of the concentration change front of the mixture components is in the order of 100-500 microseconds;

[0085] - The claimed device is resistant to contamination, which ensures the stability of the operation of the transport device and the stability of the overall mass spectrometer or IMS (ion mobility spectrometer) characteristics under conditions of high device load and continuous analysis.

Claims

1. A device for transporting and focusing ions, characterized in that The invention comprises an ion source, a surface provided with a radio frequency electrode array, and at least one electrode arranged opposite to the surface and jointly constituting an ion transmission channel, wherein at least one DC potential is applied to the at least one electrode, and the surface with the radio frequency electrode array is arranged along the ion transmission channel.

2. The device according to claim 1, characterized in that The radio frequency electrode array has a repeating pattern and is composed of a plurality of electrode groups, each group consisting of N electrodes that are repeated along a tangential direction.

3. The device according to claim 1, characterized in that The RF electrode array and the DC electrode arranged opposite to the RF electrode array gradually narrow toward the device outlet, thereby compressing the ion packets in two directions: perpendicular to the surface (Y axis) and along the lateral direction of the device (X axis).

4. The device according to claim 2, characterized in that The size of the pattern and the pattern itself vary along the tangential direction.

5. The device according to claim 2, characterized in that The device is configured to apply N time-varying potentials to a plurality of electrode groups, each group consisting of N electrodes of the radio frequency electrode array.

6. The device according to claim 5, characterized in that N alternating current voltages are applied to a plurality of electrode groups, each group comprising N electrodes of the radio frequency electrode array, wherein the phases of the alternating current voltages are shifted by at least 2π / N relative to adjacent electrodes in the group.

7. The device according to claim 2, characterized in that The apparatus is configured to apply radio frequency voltages with a phase difference of π to adjacent electrodes in the radio frequency electrode array.

8. The device according to claim 1, characterized in that At least a portion of the electrodes in the electrode array are in the shape of a rectangle, an angular curved strip, a curved strip that is a portion of an ellipse, or a curved strip that is a portion of a ring.

9. The device according to claim 1, characterized in that The radio frequency electrode array has a flat insulating substrate and can be realized by printed circuit board technology.

10. The device according to claim 1, characterized in that In addition to the RF electrode array, the surface further comprises at least one or more electrodes with a DC potential applied thereto disposed at the edge of the surface to form a constant electric field or RF electric field that guides ions toward the central axis of the ion transport channel.

11. The device according to claim 1, characterized in that The electrodes with DC potential and arranged opposite to the radio frequency electrode array are made into plate-shaped, mesh-shaped or other linear structures.

12. The device according to claim 1, characterized in that The outlet of the device is also connected to a downstream device, which is composed of similar radio frequency electrode arrays arranged opposite to each other. These arrays form similar traveling wave fields for confining ions within the ion transport channel and transporting them along the channel.

13. The device according to claim 1, characterized in that The ion source is the preceding stage of a differential pumping interface, or a device for separation based on ion characteristics, or any ion source operating at near atmospheric pressure, fore vacuum, or high vacuum pressure.

14. A method for transporting and focusing ions, the method being implemented by an apparatus comprising an ion source, a surface provided with an array of radio frequency electrodes and arranged along an ion transport channel, and at least one electrode disposed opposite the surface and together forming the ion transport channel, the electrode being applied with at least one DC potential, wherein: The method comprises the following steps: directing a stream of gaseous ions from an ion source to a space between a surface having an array of radio frequency electrodes and an electrode having a direct current potential; forming an electric field that draws ions from at least one electrode having a DC potential toward a surface having an array of radio frequency electrodes; An electric field is formed to push ions away from the surface and guide the ions into an ion transmission channel formed between the electrode array and at least one electrode with a DC potential, where the ions are confined in the channel and move toward the device outlet.

15. The method according to claim 14, characterized in that The movement of ions along the axial direction toward the device outlet is achieved by applying a power supply voltage to the electrode array to form a traveling wave electric field.

16. The method according to claim 14, characterized in that The movement of ions towards the device outlet is achieved by applying a flow of neutral gas from the ion source in an axial direction.

17. The method according to claim 14, characterized in that The movement of ions toward the device outlet is achieved by the axial DC electric field component formed by the electrode group.

18. The method according to claim 14, characterized in that The gaseous ion stream is directed along an axis that is inclined relative to the surface carrying the electrode array so that a substantial portion of neutral components, including pollutants, are not deposited on the electrode array and inlet portions of downstream devices.

19. The method according to claim 15, characterized in that A time-varying voltage is applied to alternating electrode groups with a phase shift relative to adjacent electrode groups to form the traveling wave electric field.

20. The method according to claim 19, characterized in that Within each electrode group, from the first electrode to the last electrode in the direction of ion movement, the voltage phases on adjacent electrodes are shifted to form potential peaks and potential valleys that move in the tangential direction.

21. The method according to claim 19, wherein At a first moment t1 , a first voltage is applied to the first electrodes of all electrode groups, a second voltage is applied to the second electrodes of all electrode groups, and so on.

22. The method according to claim 19, wherein At a second time t2, the first voltage is applied to the second electrode of each electrode group, the second voltage is applied to the third electrode of each electrode group, and so on.

23. The method according to claim 15, wherein The power supply is applied in such a way that an inverted signal with a higher frequency is applied to adjacent electrodes, and another signal with a different frequency is superimposed on this signal, wherein the frequency of the superimposed signal is several times lower than that of the first signal and has a phase shift relative to the adjacent electrodes in the electrode group, and the phase shift is distributed to each of the electrode groups.

24. The method according to claim 15, wherein The power supply voltage is a sine signal, a rectangular wave, a triangle wave or a sawtooth waveform.

25. The method according to claim 15, wherein The supply voltage is varied depending on the operating mode of the device, ie accumulation mode or ion transport mode, by alternating these modes to form ion packets of the desired duration.

26. The method according to claim 25, characterized in that In the accumulation mode, power is applied to the electrode array in a manner that prevents ions from being deposited on device surfaces but also from entering downstream devices.

27. The method according to claim 25, characterized in that In the ion transmission mode, a radio frequency voltage is applied to the electrode array to form a traveling wave field or other guiding electric field that guides ions toward the device outlet.

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