Ion guide electrode configuration for polarity-independent ion confinement

Abstract

To simplify a structure and operation of an ion guide.SOLUTION: An ion guide includes a first arrangement of electrodes on a first surface, a second arrangement of electrodes on a second surface, and an ion containment space in a gap therebetween. The first arrangement includes first electrodes and second electrodes. Each first electrode includes a first main portion and a first edge portion. The first edge portion is wider than the first main portion. The second arrangement includes third electrodes and fourth electrodes. Each fourth electrode includes a fourth main portion and a fourth edge portion. The fourth edge portion is wider than the fourth main portion. The first edge portions are positioned opposite the fourth edge portions. The first electrodes and the third electrodes are configured to receive a first RF voltage, and the second electrodes and the fourth electrodes are configured to receive a second RF voltages that is phase-shifted with respect to the first RF voltage.SELECTED DRAWING: Figure 1

Description

Background Art

[0001] An ion guide is a device that guides ions along an ion path by application of electrostatic and electrodynamic fields, and / or by means of a carrier gas. Ion guides can be used, for example, to transport ions within mass spectrometers or to separate ions within ion mobility devices. Conventional ion guides are formed from a multipole array such as a linear quadrupole device, or an array of electrodes on opposing surfaces such as printed circuit boards (PCBs). PCB ion guides are attractive due to their low cost and the possibility of creating complex geometries with a fairly simple printing process. However, conventional configurations of PCB ion guides have various drawbacks. For example, in order to keep ions within the ion path, some PCB ion guides apply a radio frequency (RF) voltage to inner RF electrodes to provide a trapping potential in the Y (vertical) direction, and apply a direct current (DC) voltage to outer guard electrodes to provide a trapping potential in the X (horizontal) direction. Ions are guided along the ion path along the Z-axis. However, the trapping potential generated by DC guard electrodes can only trap ions of a single polarity. Other PCB ion guides use additional RF electrodes positioned in the space between an upper PCB and a lower PCB to provide polarity-independent trapping along the X-axis. However, these additional RF guard electrodes require additional drive electronics and complicate the design and manufacturing of the ion guide. Summary of Invention

[0002] The following description provides a simplified overview of one or more embodiments of the methods and systems described herein in order to provide a basic understanding of such embodiments. This overview is not intended to be a comprehensive overview of all intended embodiments, nor to identify the main or important elements of all embodiments, nor to delineate the scope of any or all embodiments. Its sole purpose is to present, in a simplified form, some concepts of one or more embodiments of the methods and systems described herein as a prelude to the more detailed description presented below.

[0003] In some exemplary embodiments, the ion guide comprises a first surface, a second surface positioned opposite the first surface, and a plurality of electrodes including a first array of electrodes on the first surface and a second array of electrodes on the second surface, wherein the first array of electrodes and the second array of electrodes are positioned opposite each other and define an ion confinement space between them, the first array of electrodes comprising a first electrode and a second electrode arranged on the first surface along the longitudinal axis of the ion confinement space, each first electrode comprising a first main portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a first edge portion on the first side of the ion confinement space, the first edge portion along the longitudinal axis of the ion confinement space The second electrode array is wider than the first electrode array and comprises a third and a fourth electrode arrayed on a second surface along the longitudinal axis of the ion confinement space, each of which comprises a fourth main portion extending from a first side of the ion confinement space to a second side of the ion confinement space and a fourth edge portion on the first side of the ion confinement space, the fourth edge portion being wider than the fourth main portion along the longitudinal axis of the ion confinement space, the first edge portion of the first electrode positioned opposite the fourth edge portion of the fourth electrode, the first and third electrodes configured to receive a first RF voltage, and the second and fourth electrodes configured to receive a second RF voltage that is phase-shifted with respect to the first RF voltage.

[0004] In some exemplary embodiments, a method for inducing ions is to introduce ions into an ion guide, the ion guide comprising a first surface, a second surface positioned opposite the first surface, and a plurality of electrodes including a first array of electrodes on the first surface and a second array of electrodes on the second surface, wherein the array of electrodes is positioned opposite to each other and defines an ion confinement space between them, the array of electrodes comprising a first electrode and a second electrode arranged on the first surface along the longitudinal axis of the ion confinement space, each first electrode comprising a first main portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a first edge portion on the first side of the ion confinement space, the first edge portion along the longitudinal axis of the ion confinement space, The array of second electrodes is wider than a first main portion and comprises third and fourth electrodes alternately arranged on a second surface along the longitudinal axis of the ion confinement space, each fourth electrode comprising a fourth main portion extending from a first side of the ion confinement space to a second side of the ion confinement space and a fourth edge portion on the first side of the ion confinement space, the fourth edge portion being wider than the fourth main portion along the longitudinal axis of the ion confinement space, the first edge portion of the first electrode being positioned opposite the fourth edge portion of the fourth electrode, the array of second electrodes is wider than a first main portion and comprises a fourth edge portion extending from a first side of the ion confinement space to a second side third and fourth electrodes alternately arranged on a second surface along the longitudinal axis of the ion confinement space, each fourth electrode comprising a fourth main portion extending from a first side of the ion confinement space to a second side of the ion confinement space and a fourth edge portion on the first side of the ion confinement space, the first edge portion of the first electrode being positioned opposite the fourth edge portion of the fourth electrode, the array of second electrodes is wider than a first main portion and comprises third and fourth electrodes alternately arranged on a second surface along the longitudinal axis of the ion confinement space, each fourth electrode comprising a fourth main portion extending from a first side of the ion confinement space to a second side of the ion confinement space and each fourth electrode is wider than a first main portion and comprises a fourth edge portion extending from a first side of the ion confinement space to a second side of the ion confinement space, each fourth electrode is wider than a first main portion and comprises a fourth edge portion extending from a first side of the ion confin

[0005] In some exemplary embodiments, the ion guide comprises a first surface, a second surface positioned opposite the first surface, and a plurality of electrodes including a first electrode array on the first surface and a second electrode array on the second surface, wherein the first electrode array and the second electrode array are positioned opposite each other and define an ion confinement space between them, the first electrode array comprising a first electrode and a second electrode arranged on the first surface along the longitudinal axis of the ion confinement space, the second electrode array comprising a third electrode and a fourth electrode alternately arranged on the second surface along the longitudinal axis of the ion confinement space, and the first electrode and the third electrode receiving an RF voltage of the same phase. The device is configured such that the second and fourth electrodes have the same phase and are configured to receive RF voltages that are phase-shifted with respect to the RF voltages received by the first and third electrodes; the opposing main portions of the first and third electrodes, and the opposing main portions of the second and fourth electrodes, are configured to generate a surface confinement electric field that suppresses the movement of ions in the ion confinement space toward the first and second surfaces; and the opposing edge portions of the first and fourth electrodes are configured to receive RF voltages that are phase-shifted with respect to each other and generate a first edge confinement electric field that suppresses the movement of ions in the ion confinement space toward the first side of the ion confinement space.

[0006] In some exemplary embodiments, the ion guide includes a first surface, a second surface positioned opposite the first surface, a plurality of electrodes including a first electrode array on the first surface and a second electrode array on the second surface, and an ion confinement space between the first electrode array and the second electrode array, wherein the first electrode array comprises a first electrode and a second electrode arranged on the first surface along the longitudinal axis of the ion confinement space, and the second electrode array comprises a third electrode and a fourth electrode arranged on the second surface along the longitudinal axis of the ion confinement space. The first main portion of the first electrode is positioned opposite the third main portion of the third electrode, the second main portion of the second electrode is positioned opposite the fourth main portion of the fourth electrode, and the first edge portion of the first electrode is positioned opposite the fourth edge portion of the fourth electrode on the first side of the ion confinement space. The first and third electrodes are configured to receive an RF voltage, and the second and fourth electrodes are configured to receive an RF voltage that is phase-shifted with respect to the RF voltage received by the first and third electrodes.

[0007] In some exemplary embodiments, a method for fabricating an ion guide includes arranging a first electrode and a second electrode on a first surface in the arrangement of the first electrode; arranging a third electrode and a fourth electrode on a second surface in the arrangement of the second electrode; and positioning the first surface opposite the second surface such that the arrangement of the first electrode and the arrangement of the second electrode define an ion confinement space between them, wherein the first principal portion of the first electrode is positioned opposite the third principal portion of the third electrode, and the second principal portion of the second electrode is positioned opposite the fourth electrode The arrangement of the first electrodes and the arrangement of the second electrodes are positioned opposite to a fourth main portion of the ion confinement space, such that the first edge portion of the first electrode is positioned opposite to the fourth edge portion of the fourth electrode on the first side of the ion confinement space, and the first electrodes and the third electrodes are connected to a first circuit configured to receive an RF voltage, and the second electrodes and the fourth electrodes are connected to a second circuit configured to receive an RF voltage that is phase-shifted with respect to the RF voltage received by the first circuit.

[0008] In some exemplary embodiments, the ion guide comprises a plurality of electrodes arranged on opposing surfaces, defining an ion confinement space between the opposing surfaces, each electrode comprising an elongated main portion and an edge portion at the end of the main portion, the edge portion being wider than the main portion along the longitudinal axis of the ion confinement space, the electrodes configured to receive an RF voltage, and the electrodes are arranged such that the opposing main portions receive an RF voltage of the same phase, and the opposing edge portions receive an RF voltage that is phase-shifted relative to each other. [Brief explanation of the drawing]

[0009] 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 1] This is a perspective view of an exemplary ion guide. [Figure 2] Figure 1 shows a plan view of the ion guide. [Figure 3A] Figure 2 shows cross-sectional views of the ion guides in Figures 1 and 2, taken along the dashed lines labeled IIIA and IIIB, respectively. [Figure 3B] Figure 2 shows cross-sectional views of the ion guides in Figures 1 and 2, taken along the dashed lines labeled IIIA and IIIB, respectively. [Figure 4A] Figure 2 shows cross-sectional views of the ion guides from Figures 1 and 2, taken along the dashed lines labeled IVA, IVB, and IVC, respectively. [Figure 4B] Figure 2 shows cross-sectional views of the ion guides from Figures 1 and 2, taken along the dashed lines labeled IVA, IVB, and IVC, respectively. [Figure 4C]Figure 2 shows cross-sectional views of the ion guides from Figures 1 and 2, taken along the dashed lines labeled IVA, IVB, and IVC, respectively. [Figure 5] Figures 1 and 2 show cross-sectional views of the ion guide and equipotential lines of the exemplary confinement electric field generated by the electrodes of the ion guide when the electrodes receive an RF voltage. [Figure 6A] Figures 1 and 2 show cross-sectional views of the ion guide and equipotential lines of the exemplary confinement electric field generated by electrode 108 when electrode 108 receives an RF voltage. [Figure 6B] Figures 1 and 2 show cross-sectional views of the ion guide and equipotential lines of the exemplary confinement electric field generated by electrode 108 when electrode 108 receives an RF voltage. [Figure 7] This shows an alternative configuration for surface electrodes. [Figure 8] This shows an alternative configuration for surface electrodes. [Figure 9] Another exemplary ion guide is shown in a perspective view. [Figure 10] Figure 9 shows a plan view of the ion guide. [Figure 11A] Figure 10 shows cross-sectional views of the ion guides from Figures 9 and 10, taken along dashed lines labeled XIA and XIB, respectively, and equipotential lines of the exemplary confinement electric field generated by the electrodes of the ion guide when the electrodes receive an RF voltage. [Figure 11B] Figure 10 shows cross-sectional views of the ion guides from Figures 9 and 10, taken along dashed lines labeled XIA and XIB, respectively, and equipotential lines of the exemplary confinement electric field generated by the electrodes of the ion guide when the electrodes receive an RF voltage. [Figure 12] This shows an alternative configuration for surface electrodes. [Figure 13] This shows an alternative configuration for surface electrodes. [Figure 14] This shows an alternative configuration for surface electrodes. [Figure 15] A flowchart illustrating an exemplary method for inducing ions is shown. [Figure 16] A flowchart illustrating an exemplary method for fabricating an ion guide is shown. [Modes for carrying out the invention]

[0010] Exemplary ion guides that provide polarity-independent trapping in multiple directions are described herein. In some examples, the ion guide includes a first surface (e.g., a first PCB), a second surface (e.g., a second PCB) positioned opposite the first surface, and a plurality of electrodes. The plurality of electrodes include an array of first electrodes on the first surface and an array of second electrodes on the second surface. The arrays of first and second electrodes are positioned opposite each other and define an ion confinement space between them in which ions can be confined. The array of first electrodes includes first and second electrodes arranged on the first surface along the longitudinal axis of the ion confinement space. Each first electrode includes a first principal portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a first edge portion located on the first side of the ion confinement space. The first edge portion is wider than the first principal portion along the longitudinal axis of the ion confinement space. The second electrode arrangement includes third and fourth electrodes arranged on a second surface along the longitudinal axis of the ion confinement space. Each fourth electrode includes a fourth main portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a fourth edge portion located on the first side of the ion confinement space. The fourth edge portion is wider than the fourth main portion along the longitudinal axis of the ion confinement space. The first edge portion of the first electrode is positioned opposite the fourth edge portion of the fourth electrode. The first and third electrodes are configured to receive a first RF voltage, and the second and fourth electrodes are configured to receive a second RF voltage that is phase-shifted relative to the first RF voltage.

[0011] The ion guides described herein have various advantages over conventional ion guides. For example, the electrode configurations described herein generate edge confinement and surface confinement electric fields that confine ions within an ion confinement space along a first axis (e.g., the X (horizontal) axis) and a second axis (e.g., the Y (vertical) axis), respectively, independent of ion polarity. Furthermore, the ion guides described herein have a simple structure because ion confinement along the X-axis is provided by the same electrodes that provide ion confinement along the Y-axis. Furthermore, the same RF voltage, and thus the same electronic drive circuitry, is used to generate both the edge confinement and surface confinement electric fields, thus simplifying the structure and operation of the ion guide.

[0012] Various embodiments will now be described in more detail with reference to the drawings. The systems and methods described herein may provide one or more of the above-described advantages, and / or various additional and / or alternative advantages that will become apparent herein.

[0013] 1-4C show various views of an exemplary ion guide 100. FIG. 1 shows a perspective view of the ion guide 100. FIG. 2 shows a top view of the ion guide 100. FIGS. 3A and 3B show cross-sectional views of the ion guide 100 taken along the dashed-dotted lines labeled IIIA and IIIB, respectively, in FIG. 2. FIGS. 4A-4C show cross-sectional views of the ion guide 100 taken along the dashed-dotted lines labeled IVA, IVB, and IVC, respectively, in FIG. 2.

[0014] The ion guide 100 includes a first surface 102, a second surface 104, an ion confinement space 106 between the first surface 102 and the second surface 104, and a plurality of electrodes 108 including a first electrode 108-1 and a second electrode 108-2 arranged on the first surface 102, and a third electrode 108-3 and a fourth electrode 108-4 arranged on the second surface 104. In FIGS. 1 and 2, the electrodes 108 on the first surface 102 are shown by broken lines to indicate that the electrodes 108 are positioned on the side of the first surface 102 facing the second surface 104. Although not shown, the ion guide 100 may include other components suitable for a particular implementation, such as a spacer that maintains the distance between the first surface 102 and the second surface 104, wiring for connecting the electrodes 108 to a voltage source, and an electronic device for controlling the voltage applied to the electrodes 108.

[0015] Since the ion guide 100 may have any other number and arrangement of electrodes 108, FIGS. 1 to 4C are merely representative examples of the ion guide 100. For example, although FIGS. 1, 2, and 4A show that the first surface 102 and the second surface 104 each have ten electrodes 108, the first surface 102 and the second surface 104 may have any other number of electrodes 108 as appropriate for a particular implementation.

[0016] FIGS. 1 to 4C show a legend L of an arbitrarily oriented 3D coordinate system, in which the longitudinal axis of the ion confinement space 106 (e.g., the ion propagation direction when the ion guide 100 is a transmission device) extends along the Z-axis, the first surface 102 and the second surface 104 are each in the XZ plane, and are positioned opposite to each other along the Y-axis. As used herein, the X, Y, or Z axis refers to the X, Y, or Z axis of the legend L, or any other 3D coordinate system oriented in the same manner as the legend L. For example, "X-axis" can refer to the X-axis of the legend L or any other axis parallel to the X-axis of the legend L, "Y-axis" can refer to the Y-axis of the legend L or any other axis parallel to the Y-axis of the legend L, and "Z-axis" can refer to the Z-axis of the legend L or any other axis parallel to the Z-axis of the legend L.

[0017] The first surface 102 and the second surface 104 are planar surfaces positioned substantially parallel to each other and facing each other with a gap between them. Each of the first surface 102 and the second surface 104 can be mounted by any suitable planar structure such as a PCB or a solid substrate (e.g., a glass substrate, ceramic substrate, polymer substrate, etc.). In other embodiments, the first surface 102 and the second surface 104 are not planar and have curved, undulating, or other non-planar shapes to suit specific mounting applications.

[0018] The ion confinement space 106 is the volume within the gap between the first surface 102 and the second surface 104, within which ions can be confined (e.g., captured, induced, etc.). As will be described in more detail below, a pair of opposing electrodes 108 across the ion confinement space 106 receive an RF voltage and generate a surface confinement electric field and an edge confinement electric field to confine the ions within the ion confinement space 106. The ion confinement space 106 may be under vacuum, low pressure, or high pressure.

[0019] In some examples, the ion guide 100 is a transfer-type device in which the ion confinement space 106 forms an ion path through which ions are induced. Ions can be induced (e.g., driven) through the ion confinement space 106 in any preferred manner, such as by applying DC and / or RF voltages to electrodes 108 (or other electrodes not shown) to create a DC gradient field (e.g., by using a voltage divider), a DC traveling wave (e.g., a DC pulse moving from one electrode to the next), and / or by superimposing an RF field on the confinement electric field. Additionally or alternatively, ions may be induced through the ion confinement space 106 by passing a carrier gas through the ion confinement space 106. In other examples, the ion guide 100 is a trapping-type device in which the ion confinement space 106 is a trapping volume that traps ions until they are released from the ion confinement space 106.

[0020] Referring here to Figure 2, the ion confinement space 106 includes an inlet opening 202, an outlet opening 204, a first side 206, and a second side 208. The inlet opening 202 is an opening for introducing ions into the ion confinement space 106, and the outlet opening 204 is an opening through which ions can exit or be released from the ion confinement space 106. The inlet opening 202 is located at the upstream end of the longitudinal axis of the ion confinement space 106, and the outlet opening 204 is located at the downstream end of the longitudinal axis of the ion confinement space 106. However, the inlet opening 202 and / or the outlet opening 204 may be located at any other location to suit a particular implementation. The first side 206 and the second side 208 extend opposite to each other along the longitudinal axis (e.g., the Z-axis) of the ion confinement space 106. For example, as shown in Figure 2, the first side 206 is located on the -X side of the ion confinement space 106, and the second side 208 is located on the +X side of the ion confinement space 106.

[0021] Referring again to Figures 1 to 4C, the electrodes 108 are formed from a conductive material (e.g., metal) and configured to receive an RF voltage. Each electrode 108 has a main portion 110 and an edge portion 112. For example, each first electrode 108-1 has a first main portion 110-1 and a first edge portion 112-1, each second electrode 108-2 has a second main portion 110-2 and a second edge portion 112-2, and so on.

[0022] As shown in the figure, each main portion 110 has an elongated rectangular shape and extends along the X-axis (for example, along an axis perpendicular to the longitudinal axis of the ion confinement space 106 and parallel to the first surface 102 and the second surface 104) from the first side 206 to the second side 208 of the ion confinement space 106. However, the main portions 110 are not limited to this configuration and may have any other suitable shape (e.g., curved, elliptical, oval, wavy, or irregular) and / or orientation with respect to the longitudinal axis of the ion confinement space 106. As described below, a pair of opposing main portions 110 receiving RF voltages of the same phase generate a surface confinement electric field that suppresses ions from moving toward the first surface 102 and the second surface 104 within the ion confinement space 106.

[0023] Each edge portion 112 is formed at the end (along the X-axis) of the main portion 110 and is wider than the main portion 110 along the longitudinal axis (e.g., along the Z-axis) of the ion confinement space 106. As shown in Figures 1 and 2, the electrode 108 has an L-shape, but other shapes are also possible, some of which are described below in alternative examples. In examples where the main portion 110 is not rectangular or straight (e.g., elliptical, curved, wavy, or irregular), the edge portion 112 may be wider than the directly adjacent end of the main portion 110 to which the edge portion 112 is connected. Additionally or alternatively, the edge portion 112 may be wider than the average or maximum width of the main portion 110. As shown in Figures 1 to 4C, each edge portion 112 extends along the longitudinal axis of the ion confinement space 106, beyond all or part of the main portion 110 of the adjacent electrode 108 (for example, overlapping all or part of the main portion 110 when viewed along the X direction). As described below, opposing edge portions 112 that receive RF voltages that are phase-shifted relative to each other generate edge confinement electric fields that suppress ions from moving toward the first side 206 and the second side 208 of the ion confinement space 106.

[0024] As described above, the first surface 102 includes a first array 114 of electrodes 108, and the second surface 104 includes a second array 116 of electrodes 108 positioned opposite the first array 114. The first array 114 and the second array 116 define an ion confinement space 106 between them.

[0025] The first array 114 includes alternately arranged first electrodes 108-1 and second electrodes 108-2 such that each edge portion 112 extends beyond all or part of the main portion 110 of an adjacent first electrode 108-1 or second electrode 108-2 along the longitudinal axis of the ion confinement space 106. As shown in Figures 1, 2, 4B, and 4C, each first edge portion 112-1 of the first electrode 108-1 extends beyond the second main portion 110-2 of the next (or previous) adjacent second electrode 108-2 (in the -Z direction). Similarly, each second edge portion 112-2 of the second electrode 108-2 extends beyond the first main portion 110-1 of the next (or previous) adjacent first electrode 108-1 (in the -Z direction). In an alternative configuration (not shown), the edge portions 112 of a pair of adjacent electrodes 108 extend beyond each other. For example, the first edge portion 112-1 of the first electrode 108-1 may extend beyond all or part of the second main portion 110-2 of the adjacent second electrode 108-2 (in the -Z direction), and the second edge portion 112-2 of the second electrode 108-2 may extend beyond all or part of the first main portion 110-1 of the adjacent first electrode 108-1 (in the +Z direction).

[0026] The second array 116 includes alternately arranged third electrodes 108-3 and fourth electrodes 108-4 such that each edge portion 112 extends beyond all or part of the main portion 110 of an adjacent third electrode 108-3 or fourth electrode 108-4 along the longitudinal axis of the ion confinement space 106. As shown in Figures 1, 2, 4B, and 4C, each third edge portion 112-3 of the third electrode 108-3 extends beyond the fourth main portion 110-4 of the next (or previous) adjacent fourth electrode 108-4 (in the -Z direction). Similarly, each fourth edge portion 112-4 of the fourth electrode 108-4 extends beyond the third main portion 110-3 of the next (or previous) adjacent third electrode 108-3 (in the -Z direction). In an alternative configuration (not shown), the edge portions 112 of a pair of adjacent electrodes 108 extend beyond each other. For example, the third edge portion 112-3 of the third electrode 108-3 may extend beyond all or part of the fourth main portion 110-4 of the adjacent fourth electrode 108-4 (in the -Z direction), and the fourth edge portion 112-4 of the fourth electrode 108-4 may extend beyond all or part of the third main portion 110-3 of the adjacent third electrode 108-3 (in the +Z direction).

[0027] In the configuration described above, each edge portion 112 extends along the longitudinal axis of the ion confinement space 106, beyond all or part of the main portion 110 of the adjacent electrode 108. Thus, the first edge portion 112-1 of the first electrode 108-1 is positioned adjacent to each other along the first side 206 of the ion confinement space 106, and the second edge portion 112-2 of the second electrode 108-2 is positioned adjacent to each other along the second side 208 of the ion confinement space 106. Similarly, the third edge portion 112-3 of the third electrode 108-3 is positioned adjacent to each other along the second side 208 of the ion confinement space 106, and the fourth edge portion 112-4 of the fourth electrode 108-4 is positioned adjacent to each other along the first side 206 of the ion confinement space 106.

[0028] As described above, electrode 108 is configured to receive an RF voltage and generate a surface confinement electric field and an edge confinement electric field to confine ions within the ion confinement space 106. In the above configuration, the first electrode 108-1 and the third electrode 108-3 are configured to receive RF voltages having the same phase, while the second electrode 108-2 and the fourth electrode 108-4 are configured to receive RF voltages that are in the same phase but phase-shifted relative to the RF voltages received by the first electrode 108-1 and the third electrode 108-3. In the figure, the first phase electrodes 108 (e.g., the first electrode 108-1 and the third electrode 108-3) are shown in white, and the second opposite phase electrodes 108 (e.g., the second electrode 108-2 and the fourth electrode 108-4) are shaded. In some examples, the RF voltages received by the first electrode 108-1 and the third electrode 108-3 are 180° out of phase with the RF voltages received by the second electrode 108-2 and the fourth electrode 108-4. Thus, the first array 114 and the second array 116 can be positioned opposite each other such that pairs of opposing main portions 110 receive RF voltages that are either in the same phase or phase-shifted relative to each other, and pairs of opposing edge portions 112 receive RF voltages that are phase-shifted relative to each other.

[0029] For example, as shown in Figures 1, 3A, and 4A, the first main portion 110-1 of the first electrode 108-1 is positioned opposite the third main portion 110-3 of the third electrode 108-3. Similarly, as shown in Figures 1, 3B, and 4A, the second main portion 110-2 of the second electrode 108-2 is positioned opposite the fourth main portion 110-4 of the fourth electrode 108-4. As shown in Figures 1, 3A, 3B, and 4B, on the first side 206 of the ion confinement space 106, the first edge portion 112-1 of the first electrode 108-1 is positioned opposite the fourth edge portion 112-4 of the fourth electrode 108-4. As shown in Figures 1, 3A, 3B, and 4C, on the second side 208 of the ion confinement space 106, the second edge portion 112-2 of the second electrode 108-2 is positioned opposite the third edge portion 112-3 of the third electrode 108-3.

[0030] In some examples, the first electrode 108-1 and the third electrode 108-3 are connected to a first circuit (not shown) configured to supply a first RF voltage from a voltage source (not shown), and the second electrode 108-2 and the fourth electrode 108-4 are connected to a second circuit (not shown) configured to supply a second RF voltage from the same or a different voltage source. The second RF voltage is phase-shifted relative to the first RF voltage. In examples where the voltage source is the same for both the first and second circuits, either the first or second circuit may include any suitable phase-shift circuit or phase-shift module.

[0031] As shown in Figure 1, the edge portions 112 of the L-shaped electrodes 108 of the first array 114 (e.g., the first electrode 108-1 and the second electrode 108-2) extend in the same direction (e.g., the -Z direction) as the edge portions 112 of the L-shaped electrodes 108 of the second array 116 (e.g., the third electrode 108-3 and the fourth electrode 108-4). In an alternative configuration, the edge portions 112 of the L-shaped electrodes 108 of the first array 114 extend along the Z axis in the opposite direction (e.g., the +Z direction) to the edge portions 112 of the L-shaped electrodes 108 of the second array 116 (e.g., the -Z direction).

[0032] The operation of the ion guide 100 will now be described with reference to Figures 5, 6A, and 6B. Figure 5 is similar to Figure 4A and shows a cross-sectional view of the ion guide 100 and equipotential lines of an exemplary confinement electric field generated by the electrode 108 when the electrode 108 receives an RF voltage. Figures 6A and 6B are similar to Figures 3A and 3B, respectively and show a cross-sectional view of the ion guide 100 and equipotential lines of an exemplary confinement electric field generated by the electrode 108 when the electrode 108 receives an RF voltage. When the electrode 108 receives an RF voltage, the main portion 110 and edge portion 112 of the electrode 108 generate a confinement electric field to confine the ions 502 within the ion confinement space 106, as described below.

[0033] The opposing pairs of principal portions 110 of the first electrode 108-1 and the third electrode 108-3 generate a surface confinement electric field. As shown in Figures 5 and 6A, the first principal portion 110-1 of the first electrode 108-1 on the first surface 102 generates a first surface confinement electric field 504-1, and the third principal portion 110-3 of the third electrode 108-3 on the second surface 104 generates a second surface confinement electric field 504-2. The opposing first principal portion 110-1 of the first electrode 108-1 and the third principal portion 110-3 of the third electrode 108-3 receive RF voltages with the same phase, but they are phase-shifted with respect to the RF voltages received by the adjacent second electrode 108-2 and fourth electrode 108-4, so that a low-potential region is formed in the ion confinement space 108 between the first surface 102 and the second surface 104.

[0034] The opposing pair of the main portion 110-2 of the second electrode 108-2 and the fourth main portion 110-4 of the fourth electrode 108-4 also generates a surface confinement electric field. As shown in Figures 5 and 6B, the second main portion 110-2 of the second electrode 108-2 on the first surface 102 also generates a first surface confinement electric field 504-1, and the fourth main portion 110-4 of the fourth electrode 108-4 on the second surface 104 also generates a second surface confinement electric field 504-2. The second main portion 110-2 of the opposing second electrode 108-2 and the fourth main portion 110-4 of the fourth electrode 108-4 receive RF voltages with the same phase, but they are phase-shifted with respect to the RF voltages received by the adjacent first electrode 108-1 and third electrode 108-3, so that a low-potential region is formed in the ion confinement space 106 between the first surface 102 and the second surface 104.

[0035] The first surface confinement electric field 504-1, generated by the first major portion 110-1 and the second major portion 110-2 on the first surface 102, is a trapping potential that suppresses the movement of ions 502 toward the first surface 102. The second surface confinement electric field 504-2, generated by the third major portion 110-3 and the fourth major portion 110-4 on the second surface 104, is also a trapping potential that suppresses the movement of ions 502 toward the second surface 104.

[0036] On the first side 206 and the second side 208 of the ion confinement space 106, opposing edge portions 112 generate an edge confinement electric field. As shown in Figure 6A, on the first side 206 of the ion confinement space 106, the first edge portion 112-1 of the first electrode 108-1 on the first surface 102 is positioned opposite the fourth edge portion 112-4 of the fourth electrode 108-4 on the second surface 104. Since the first edge portion 112-1 and the fourth edge portion 112-4 receive RF voltages that are phase-shifted relative to each other, a first edge confinement electric field 602-1 is generated on the first side 206. The first edge confinement electric field 602-1 is a trapping potential that causes ions 502 to move toward the first side 206 and suppresses their escape from the ion confinement space 106 on the first side 206.

[0037] As shown in Figure 6B, on the second side 208 of the ion confinement space 106, the second edge portion 112-2 of the second electrode 108-2 on the first surface 102 is positioned opposite the third edge portion 112-3 of the third electrode 108-3 on the second surface 104. Since the second edge portion 112-2 and the third edge portion 112-3 receive RF voltages that are phase-shifted relative to each other, a second edge confinement electric field 602-2 is generated on the second side 208. The second edge confinement electric field 602-2 is a trapping potential that causes ions 502 to move toward the second side 208 and suppresses their escape from the ion confinement space 106 on the second side 208.

[0038] When an ion is introduced into the ion confinement space 106, the first surface confinement electric field 504-1 suppresses the ion 502 from moving toward the first surface 102 in the +Y direction, and the second surface confinement electric field 504-2 suppresses the ion 502 from moving toward the second surface 104 in the -Y direction. The first edge confinement electric field 602-1 suppresses the ion 502 from moving toward the first side 206 in the -X direction, and the second edge confinement electric field 602-2 suppresses the ion 502 from moving toward the second side 208 in the +X direction.

[0039] Using this configuration, electrode 108 can receive an RF voltage and generate a surface confinement electric field 504 and an edge confinement electric field 602 to confine ions 502 within the ion confinement space 106. Since the first edge confinement electric field 602-1 and the second edge confinement electric field 602-2 are RF electric fields, electrode 108 provides polarity-independent confinement of ions 502 within the ion confinement space 106 along the X-axis. Furthermore, the first edge confinement electric field 602-1 and the second edge confinement electric field 602-2 are generated from the same electrode that generates the first surface confinement electric field 504-1 and the second surface confinement electric field 504-2, thereby simplifying the design and structure of the ion guide 100.

[0040] In the examples shown in Figures 1 to 4C, the phases of the RF voltages received by the edge portions 112 on the first surface 102 and the second surface 104 have rotational symmetry around the longitudinal axis of the ion confinement space 106. That is, the phases of the RF voltages received by the edge portions 112 are the same across the diagonal cross-section of the ion guide 100. For example, as shown in Figures 6A and 6B, the first edge portion 112-1 on the first surface 102 on the first side 206 and the third edge portion 112-3 on the second surface 104 on the second side 208 are configured to receive RF voltages having the same phase, while the second edge portion 112-2 on the first surface 102 on the second side 208 and the fourth edge portion 112-4 on the second surface 104 on the first side 206 are configured to receive RF voltages having the same phase but phase-shifted relative to the RF voltages received by the first edge portion 112-1 and the third edge portion 112-3. By using a rotationally symmetric configuration, the same surface configuration can be used for both the first surface 102 and the second surface 104. For example, the same PCB may be used for both the first surface 102 and the second surface 104, thus facilitating the manufacture of the ion guide 100 with low complexity and low cost.

[0041] In the example described above, rotational symmetry is achieved by using the L-shaped electrode 108 as described above. However, rotational symmetry may also be achieved by using other electrode shapes. Next, examples of alternative electrode shapes will be described with reference to Figures 7 and 8.

[0042] Figure 7 shows an alternative configuration of the electrode 108 on surface 700. Surface 700 may mount the first surface 102 and / or the second surface 104 of the ion guide 100. In Figure 7, each electrode 108 has a T-shape in which each edge portion 112 of the electrode 108 extends beyond the main portion 110 of the electrode 108 in both directions along the longitudinal axis of the ion confinement space 106. Thus, each edge portion 112 is wider than the main portion 110 of the electrode 108 along the longitudinal direction of the ion confinement space 106. In some examples, the edge portion 112 extends beyond at least a portion of the main portion 110 of both adjacent electrodes 108 along the longitudinal axis of the ion confinement space 106. An ion guide can be formed by rotating one surface 700 around the longitudinal axis of the ion confinement space 106, thereby positioning the two surfaces 700 facing each other, such that opposing main portions receive RF voltages of the same phase and opposing edge portions 112 receive RF voltages that are phase-shifted relative to each other.

[0043] Figure 8 shows another alternative configuration of the electrode 108 on surface 800. Surface 800 may mount the first surface 102 and / or the second surface 104 of the ion guide 100. In Figure 8, each electrode 108 has a Y shape in which each edge portion 112 of the electrode 108 flares out from the main portion 110 (for example, having a triangular shape) and extends beyond the main portion 110 of the electrode 108 in both directions along the longitudinal axis of the ion confinement space 106. Thus, each edge portion 112 is wider than the main portion 110 of the electrode 108 along the longitudinal direction of the ion confinement space 106. In some examples, the edge portions 112 extend beyond at least a portion of the main portions 110 of both adjacent electrodes 108 along the longitudinal axis of the ion confinement space 106. An ion guide can be formed by rotating one surface 800 around the longitudinal axis of the ion confinement space 106, thereby positioning the two surfaces 800 facing each other, such that opposing main portions receive RF voltages of the same phase and opposing edge portions 112 receive RF voltages that are phase-shifted relative to each other.

[0044] Figures 9 to 11B show various views of another exemplary ion guide 900. Figure 9 shows a perspective view of the ion guide 900. Figure 10 shows a plan view of the ion guide 900. Figures 11A and 11B show cross-sectional views of the ion guide 900 taken along the dashed lines labeled XIA and XIB in Figure 10, respectively. The ion guide 900 is similar to the ion guide 100, except that the phase of the RF voltage received by the edge portions 112 on the first surface 102 and the second surface 104 has X-plane mirror symmetry. That is, the phase of the RF voltage received by the edge portions 112 is the same horizontally (along the X axis) across the ion guide 100. This mirror symmetry configuration is achieved by a set of electrodes 108 (e.g., the first electrode 108-1) having edge portions 112 at both ends of a main portion 110, as described herein.

[0045] As shown in Figures 9 and 10, the first array 114 includes first electrodes 108-1 and second electrodes 108-2 arranged alternately on the first surface 102. As shown, each first electrode 108-1 includes a first edge portion 112-1 at the first end of the first main portion 110-1 (e.g., the -X side end corresponding to the first side 206 of the ion confinement space 106) and a second edge portion 112-2 at the second end of the first main portion 110-1 (e.g., the +X side end corresponding to the second side 208 of the ion confinement space 106). Both the first edge portion 112-1 and the second edge portion 112-2 are wider than the first main portion 110-1 and extend beyond the first main portion 110-1 in the same direction (e.g., the -Z direction) along the longitudinal axis of the ion confinement space 106. As a result, each of the first electrodes 108-1 has a double L shape ("LL shape"). The second electrode 108-2 has a second main portion 110-2 but no edge portion. In some examples, the first edge portion 112-1 and the second edge portion 112-2 of the first electrode 108-1 extend along the longitudinal axis of the ion confinement space 106, beyond all or part of the second main portion 110-2 of the adjacent second electrode 108-2. For example, as shown in Figures 9 and 10, the second electrode 108-2 is positioned between the first edge portion 112-1 and the second edge portion 112-2 of the adjacent first electrode 108-1.

[0046] The second array 116 includes third electrodes 108-3 and fourth electrodes 108-4 arranged alternately on the second surface 104. As shown in the figure, the third electrode 108-3 has a third main portion 110-3 but no edge portion. Each fourth electrode 108-4 includes a fourth edge portion 112-4 at the first end of the fourth main portion 110-4 (e.g., the -X side end corresponding to the first side 206 of the ion confinement space 106) and a third edge portion 112-3 at the second end of the fourth main portion 110-4 (e.g., the +X side end corresponding to the second side 208 of the ion confinement space 106). Both the third edge portion 112-3 and the fourth edge portion 112-4 are wider than the fourth main portion 110-4 and extend beyond the fourth main portion 110-4 in the same direction (e.g., the -Z direction) along the longitudinal axis of the ion confinement space 106. As a result, each of the fourth electrodes 108-4 has a double L shape ("LL shape"), similar to the first electrode 108-1. In some examples, the third edge portion 112-3 and the fourth edge portion 112-4 of the fourth electrode 108-4 extend along the longitudinal axis of the ion confinement space 106 beyond all or part of the third main portion 110-3 of the adjacent third electrode 108-3. For example, as shown in Figures 9 and 10, the third electrode 108-3 is positioned between the third edge portion 112-3 and the fourth edge portion 112-4 of the adjacent fourth electrode 108-4.

[0047] In the configuration described above, the first edge portion 112-1 of the first electrode 108-1 is positioned adjacent to each other along the first side 206 of the ion confinement space 106, and the second edge portion 112-2 of the first electrode 108-1 is positioned adjacent to each other along the second side 208 of the ion confinement space 106. Similarly, the third edge portion 112-3 of the fourth electrode 108-4 is positioned adjacent to each other along the second side 208 of the ion confinement space 106, and the fourth edge portion 112-4 of the fourth electrode 108-4 is positioned adjacent to each other along the first side 206 of the ion confinement space 106.

[0048] The electrodes 108 of the ion guide 900 are configured to receive an RF voltage and generate a surface confinement electric field and an edge confinement electric field to confine ions within the ion confinement space 106. In the above configuration, the first electrode 108-1 and the third electrode 108-3 are configured to receive RF voltages having the same phase, while the second electrode 108-2 and the fourth electrode 108-4 are configured to receive RF voltages that are in the same phase but are phase-shifted relative to the RF voltages received by the first electrode 108-1 and the third electrode 108-3. In some examples, the RF voltages received by the first electrode 108-1 and the third electrode 108-3 are 180° out of phase with the RF voltages received by the second electrode 108-2 and the fourth electrode 108-4. Therefore, the first array 114 and the second array 116 can be positioned opposite each other such that opposing pairs of main portions 110 receive RF voltages having the same phase, and opposing pairs of edge portions 112 receive RF voltages that are phase-shifted relative to each other.

[0049] For example, as shown in Figures 9 and 11A, the first array 114 is offset from the second array 116 along the Z-axis so that the first main portion 110-1 of the LL-shaped first electrode 108-1 is positioned opposite the third main portion 110-3 of the LL-shaped third electrode 108-3. Similarly, as shown in Figures 9 and 11B, the second main portion 110-2 of the LL-shaped second electrode 108-2 is positioned opposite the fourth main portion 110-4 of the LL-shaped fourth electrode 108-4. As shown in Figures 9 and 11A and 11B, on the first side 206 of the ion confinement space 106, the first edge portion 112-1 of the first electrode 108-1 is positioned opposite the fourth edge portion 112-4 of the fourth electrode 108-4. As shown in Figures 9, 11A, and 11B, on the second side 208 of the ion confinement space 106, the second edge portion 112-2 of the first electrode 108-1 is positioned opposite the third edge portion 112-3 of the fourth electrode 108-4.

[0050] As shown in Figure 9, the edge portion 112 of the LL-shaped electrode 108 of the first array 114 (e.g., the first electrode 108-1) extends in the same direction (e.g., the -Z direction) as the edge portion 112 of the LL-shaped electrode 108 of the second array 116 (e.g., the fourth electrode 108-4). In the alternative configuration, the edge portion 112 of the LL-shaped electrode 108 of the first array 114 extends along the Z axis in the opposite direction (e.g., the +Z direction) to the edge portion 112 of the L-shaped electrode 108 of the second array 116 (e.g., the -Z direction).

[0051] When electrode 108 receives an RF voltage, the main portion 110 and edge portion 112 of electrode 108 generate a confinement electric field to confine ions 502 within the ion confinement space 106. For example, a pair of opposing main portions of electrode 108 receive RF voltages with the same phase, thereby generating a first surface confinement electric field 504-1 and a second surface confinement electric field 504-2. On the first side 206 of the ion confinement space 106, opposing first edge portion 112-1 and fourth edge portion 112-4 receive RF voltages that are phase-shifted relative to each other, thereby generating a first edge confinement electric field 602-1. On the second side 208 of the ion confinement space 106, opposing second edge portion 112-2 and third edge portion 112-3 receive RF voltages that are phase-shifted relative to each other, thereby generating a second edge confinement electric field 602-2.

[0052] In the examples of Figures 9 to 11B, the phases of the RF voltages received by the edge portions 112 on the first surface 102 and the second surface 104 have mirror symmetry across the ion confinement space 106 (for example, across the YZ plane). That is, the phases of the RF voltages received by the edge portions 112 are the same horizontally (along the X axis) across the ion guide 100. For example, as shown in Figures 11A and 11B, the first edge portion 112-1 on the first surface 102 on the first side 206 and the second edge portion 112-2 on the first surface 102 on the second side 208 are configured to receive RF voltages having the same phase, while the third edge portion 112-3 on the second surface 104 on the second side 208 and the fourth edge portion 112-4 on the second surface 104 on the first side 206 are configured to receive RF voltages having the same phase but being phase-shifted with respect to the RF voltages received by the first edge portion 112-1 and the second edge portion 112-2.

[0053] In the example described above, the mirror-symmetric configuration is achieved by using the LL-shaped electrode 108, as stated above. However, the mirror-symmetric configuration may also be achieved by using other electrode shapes. Next, examples of alternative electrode shapes will be described with reference to Figures 12 to 14.

[0054] Figure 12 shows another alternative configuration of electrode 108 on surface 1200. Surface 1200 may mount the first surface 102 and / or second surface 104 of ion guide 900. In Figure 12, the first edge portion 112-1 and the second edge portion 112-2 of the same electrode 108 extend in opposite directions along the Z axis. As shown, the first edge portion 112-1 extends in the -Z direction, while the second edge portion 112-2 extends in the +Z direction. Thus, each of the first electrodes 108-1 has a double L shape ("LL shape"), while the second electrode 108-2 does not have an edge portion. In some examples, the first edge portion 112-1 extends along the longitudinal axis of the ion confinement space 106, beyond at least a portion of the second principal portion 110-2 of the adjacent second electrode 108-2 (in the +Z direction). The second edge portion 112-2 of the electrode extends along the longitudinal axis of the ion confinement space 106, beyond at least a portion of the second principal portion 110-2 of another adjacent second electrode 108-2 (in the -Z direction). The ion guide can be formed by positioning two surfaces 1200 facing each other along the longitudinal axis of the ion confinement space 106, with one surface 1200 offset, such that the opposing principal portions receive RF voltages of the same phase and the opposing edge portions 112 receive RF voltages that are phase-shifted relative to each other.

[0055] Figure 13 shows another alternative configuration of the electrode 108 on surface 1300. Surface 1300 may mount the first surface and / or second surface 104 of the ion guide 900. In Figure 13, each first electrode 108-1 includes a first edge portion 112-1 at the first end of the first main portion 110-1 (e.g., the -X side end corresponding to the first side 206 of the ion confinement space 106) and a second edge portion 112-2 at the second end of the first main portion 110-1 (e.g., the +X side end corresponding to the second side 208 of the ion confinement space 106). Both the first edge portion 112-1 and the second edge portion 112-2 extend beyond the main portion 110 in both directions along the Z axis (e.g., the +Z direction and the -Z direction). Therefore, each of the first electrodes 108-1 has a double T shape ("TT shape"), while the second electrode 108-2 does not have an edge portion. The first edge portion 112-1 and the second edge portion 112-2 extend along the longitudinal axis of the ion confinement space 106 beyond at least a portion of the second principal portion 110-2 of both adjacent second electrodes 108-2. The ion guide can be formed by positioning two surfaces 1300 facing each other along the longitudinal axis of the ion confinement space 106, with one surface 1300 offset, such that the opposing principal portions receive RF voltages of the same phase and the opposing edge portions 112 receive RF voltages that are phase-shifted relative to each other.

[0056] Figure 14 shows another alternative configuration of electrode 108 on surface 1400. Surface 1400 may mount the first surface and / or second surface 104 of ion guide 900. Figure 14 is similar to Figure 13, except that the first electrode 108-1 has a double Y shape ("YY shape"). In Figure 14, the first electrode 108-1 includes a first edge portion 112-1 at the first end of the first main portion 110-1 (e.g., the -X side end corresponding to the first side 206 of the ion confinement space 106) and a second edge portion 112-2 at the second end of the first main portion 110-1 (e.g., the +X side end corresponding to the second side 208 of the ion confinement space 106). Both the first edge portion 112-1 and the second edge portion 112-2 flare out from the first main portion 110-1 (for example, in a triangular shape) and extend beyond the first main portion 110-1 in both directions along the Z axis (for example, in the +Z and -Z directions). The second electrode 108-2 does not have an edge portion. The first edge portion 112-1 and the second edge portion 112-2 extend beyond at least a portion of the second main portion 110-2 of both adjacent second electrodes 108-2 along the longitudinal axis of the ion confinement space 106. An ion guide can be formed by positioning two surfaces 1400 facing each other along the longitudinal axis of the ion confinement space 106, with one surface 1400 offset, such that the opposing main portions receive RF voltages of the same phase and the opposing edge portions 112 receive RF voltages that are phase-shifted relative to each other.

[0057] Various modifications can be made to the apparatus described herein. In some examples, the first array 114 and the second array 116 are offset from each other along the longitudinal axis of the ion confinement space 106 such that the main portions 110 of the electrodes 108 that receive RF voltages of the same phase are not positioned directly opposite each other. For example, opposing main portions 110 can receive RF voltages that are phase-shifted relative to each other. Thus, the first main portion 110-1 may be positioned opposite the fourth main portion 110-4, and the second main portion 110-2 may be positioned opposite the third main portion 110-3. In other configurations, the first array 114 and the second array 116 are offset from each other along the longitudinal axis of the ion confinement space 106 such that the first main portion 110-1 and the second main portion 110-2 are positioned partially or entirely opposite each other in the gap between the adjacent third main portion 110-3 and the fourth main portion 110-4. Similarly, the third main portion 110-3 and the fourth main portion 110-4 are positioned partially or entirely opposite each other in the gap between the adjacent first main portion 110-1 and the second main portion 110-2. Due to the shape of the edge portions 112 of the electrode 108, the offset configuration of the first array 114 and the second array 116 does not alter the phase of the RF voltage or the edge confinement electric field received by the opposing edge portions 112.

[0058] In some examples, the first array 114 on the first surface 102 is different from the second array 116 on the second surface 104. For example, the first array 114 may have the configuration shown in Figure 2, and the second array 116 may have the configuration shown in Figure 7 or Figure 8. In another example, the first array 114 may have the configuration shown in Figure 10 and any one of Figures 12 to 14, and the second array 116 may have any other configuration shown in Figures 10 and any other of Figures 12 to 14.

[0059] In some embodiments, the first array 114 and / or the second array 116 include combinations of different electrode shapes. For example, the first array 114 and / or the second array 116 may include any combination of L-shaped electrodes 108, T-shaped electrodes 108, and Y-shaped electrodes 108. As another example, the first array 114 and / or the second array 116 may include any combination of LL-shaped electrodes 108, TT-shaped electrodes 108, and YY-shaped electrodes 108.

[0060] In the example above, the edge portion 112 is rectangular (L-shaped or T-shaped electrode) or triangular (Y-shaped electrode). However, the edge portion 112 may have any other shape (e.g., rounded shape, elliptical shape, irregular shape, etc.) that is suitable for a particular implementation.

[0061] In the example described above, the edge portion 112 is formed integrally with the main portion 110. In other embodiments, the edge portion 112 and the main portion 110 are formed separately but are electrically connected to receive the same RF voltage (e.g., by vias, traces, wires, relays, etc.).

[0062] In the example described above, the electrodes 108 are arranged to form a linear (straight) ion path. In other embodiments, the electrodes 108 are arranged to form a nonlinear ion path. For example, the ion path may include one or more bends, turns, curves, and / or angles. Furthermore, the ion guides described herein may include multiple ion paths and one or more junctions or intersections with other ion paths.

[0063] Figure 15 shows a flow chart of an exemplary method 1500 for inducing ions. While Figure 15 shows an exemplary operation according to one embodiment, other embodiments may omit, add, rearrange, and / or modify one or more operations of method 1500 shown in Figure 15. Each operation of method 1500 shown in Figure 15 may be performed in any manner described herein.

[0064] In operation 1502, an RF voltage is applied to electrodes contained within an ion guide (e.g., ion guide 100 or ion guide 900) configured as described herein. For example, the ion guide includes a first surface, a second surface positioned opposite the first surface, and a plurality of electrodes including an array of first electrodes on the first surface and an array of second electrodes on the second surface, the arrays of first and second electrodes positioned opposite each other and defining an ion confinement space between them. The plurality of electrodes are configured as described herein. For example, an electrode included in the plurality of electrodes has a main portion and an edge portion that is wider than the main portion.

[0065] In operation 1504, ions are introduced into the ion guide. When the multiple electrodes receive an RF voltage, the multiple electrodes generate a surface confinement electric field and an edge confinement electric field that provide polarity-independent confinement of ions within the ion confinement space along a first axis (e.g., the Y axis) perpendicular to the longitudinal axis (e.g., the Z axis) of the ion guide, and along a second axis (e.g., the X axis).

[0066] Figure 16 shows a flowchart of an exemplary method 1600 for fabricating an ion guide (e.g., ion guide 100 or ion guide 900). While Figure 16 shows an exemplary operation according to one embodiment, other embodiments may omit, add, rearrange, and / or modify one or more operations of method 1600 shown in Figure 16. Each operation of method 1600 shown in Figure 16 may be performed in any manner described herein.

[0067] In operation 1602, the first plurality of electrodes are arranged on a first surface (e.g., first surface 102) in a first arrangement (e.g., first arrangement 114) along a first axis (e.g., Z axis). The plurality of electrodes are arranged as described herein. The electrodes included in the first plurality of electrodes include a principal portion and an edge portion that is wider than the principal portion along the first axis. In some examples, the electrodes have an L-shape, T-shape, Y-shape, LL-shape, TT-shape, or YY-shape.

[0068] In operation 1604, the second plurality of electrodes are arranged on a second surface (e.g., second surface 104) in a second arrangement (e.g., second arrangement 116) along a second axis (e.g., Z axis). The second plurality of electrodes are arranged as described herein. The electrodes included in the second plurality of electrodes include a principal portion and an edge portion that is wider than the principal portion along the second axis. In some examples, the electrodes have an L-shape, T-shape, Y-shape, LL-shape, TT-shape, or YY-shape.

[0069] In operation 1606, the first surface is positioned opposite the second surface such that the array of first electrodes and the array of second electrodes define an ion confinement space between them. The first and second axes extend along the longitudinal axis of the ion confinement space.

[0070] On the other hand, it will be recognized by those skilled in the art that various exemplary embodiments have been described in the foregoing description with reference to the accompanying drawings. However, it will be clear that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the scope of the invention as set forth in the following claims. For example, certain features of one embodiment described herein may 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.

[0071] The advantages and features of this disclosure can be further illustrated by the following embodiments. Example 1. Ion guide comprising: a first surface and a second surface facing each other with a gap between them; and a plurality of electrodes including an array of first electrodes on the first surface and an array of second electrodes on the second surface, wherein the array of first electrodes and the array of second electrodes are positioned facing each other and define an ion confinement space within the gap, wherein the array of first electrodes comprises a first electrode and a second electrode arranged on the first surface along the longitudinal axis of the ion confinement space, and each first electrode comprises a first main portion extending from the first side of the ion confinement space to the second side of the ion confinement space, and a first edge portion on the first side of the ion confinement space, wherein the first edge portion is wider than the first main portion along the longitudinal axis of the ion confinement space. An ion guide comprising: a second electrode arrangement comprising a third electrode and a fourth electrode arranged on a second surface along the longitudinal axis of the ion confinement space, each fourth electrode comprising a fourth main portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a fourth edge portion on the first side of the ion confinement space, wherein the fourth edge portion is wider than the fourth main portion along the longitudinal axis of the ion confinement space, the first edge portion of the first electrode being positioned opposite the fourth edge portion of the fourth electrode, the first electrode and the third electrode being configured to receive a first RF voltage, and the second electrode and the fourth electrode being configured to receive a second RF voltage that is phase-shifted with respect to the first RF voltage. Example 2. The ion guide according to Example 1, wherein the first electrode and the second electrode have an L-shape, a T-shape, or a Y-shape. Example 3. The ion guide according to Example 1, wherein each third electrode comprises a third main portion, and the first main portion of the first electrode is positioned opposite the third main portion of the third electrode. Example 4. The ion guide according to Example 1, wherein the first main portion of the first electrode is positioned opposite the fourth main portion of the fourth electrode. Example 5. The ion guide according to Example 1, wherein each second electrode comprises a second main portion, each third electrode comprises a third main portion, and the first main portion of the first electrode and the second main portion of the second electrode are positioned opposite each other in the gap between the third main portion of the third electrode and the fourth main portion of the fourth electrode. Example 6. An ion guide according to Example 1, wherein each second electrode comprises a second main portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a second edge portion located on the second side of the ion confinement space, wherein the second edge portion is wider than the second main portion along the longitudinal axis of the ion confinement space, and each third electrode comprises a third main portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a third edge portion located on the second side of the ion confinement space, wherein the third edge portion is wider than the third main portion along the longitudinal axis of the ion confinement space, and the second edge portion of the second electrode is positioned opposite the third edge portion of the third electrode. Example 7. The ion guide according to Example 6, wherein the second and third electrodes have an L-shape, a T-shape, or a Y-shape. Example 8. The ion guide according to Example 6, wherein the second main portion of the second electrode is positioned opposite the fourth main portion of the fourth electrode. Example 9. The ion guide according to Example 6, wherein the second main portion of the second electrode is positioned opposite the third main portion of the third electrode. Example 10. The ion guide according to Example 6, wherein the first main portion of the first electrode and the second main portion of the second electrode are positioned opposite each other in the gap between the third main portion of the third electrode and the fourth main portion of the fourth electrode. Example 11. An ion guide according to Example 1, wherein each first electrode further comprises a second edge portion on the second side of the ion confinement space, the second edge portion being wider than the first main portion along the longitudinal axis of the ion confinement space, and each fourth electrode further comprises a third edge portion on the second side of the ion confinement space, the third edge portion being wider than the fourth main portion along the longitudinal axis of the ion confinement space, and the second edge portion of the first electrode is positioned opposite the third edge portion of the fourth electrode. Example 12. The ion guide according to Example 11, wherein the first electrode and the fourth electrode have an LL shape, a TT shape, or a YY shape. Example 13. The ion guide according to Example 11, wherein the first and second edge portions extend in opposite directions along the longitudinal axis of the ion containment space. Example 14. The ion guide according to Example 11, wherein each second electrode comprises a second main portion, each third electrode comprises a third main portion, the first main portion of the first electrode is positioned opposite the third main portion of the third electrode, and the second main portion of the second electrode is positioned opposite the fourth main portion of the fourth electrode. Example 15. The ion guide according to Example 11, wherein each second electrode comprises a second main portion, each third electrode comprises a third main portion, the first main portion of the first electrode is positioned opposite the fourth main portion of the fourth electrode, and the second main portion of the second electrode is positioned opposite the third main portion of the third electrode. Example 16. The ion guide according to Example 11, wherein each second electrode comprises a second main portion, each third electrode comprises a third main portion, and the first main portion of the first electrode and the second main portion of the second electrode are positioned opposite each other in the gap between the third main portion of the third electrode and the fourth main portion of the fourth electrode. Example 17. The ion guide according to Example 11, wherein the first edge portion of the first electrode extends along the longitudinal axis of the ion confinement space to all or part of the second main portion of the adjacent second electrode. Example 18. The ion guide according to Example 17, wherein the fourth edge portion of the fourth electrode extends along the longitudinal axis of the ion confinement space beyond all or part of the third main portion of the adjacent third electrode. Example 19. The ion guide according to Example 1, wherein one or both of the first surface and the second surface are provided with a printed circuit board (PCB). Example 20. A method for inducing ions, comprising introducing ions into an ion guide, wherein the ion guide comprises a first surface and a second surface facing each other with a gap between them, and a plurality of electrodes including an array of first electrodes on the first surface and an array of second electrodes on the second surface, wherein the array of first electrodes and the array of second electrodes are positioned facing each other and defining an ion confinement space within the gap, the array of first electrodes comprising a first electrode and a second electrode arranged on the first surface along the longitudinal axis of the ion confinement space, each first electrode comprising a first main portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a first edge portion on the first side of the ion confinement space, the first edge portion being wider than the first main portion along the longitudinal axis of the ion confinement space A method comprising introducing and applying an RF voltage to a plurality of electrodes, wherein the array of second electrodes comprises a first edge portion, and the array of second electrodes comprises third and fourth electrodes alternately arranged on a second surface along the longitudinal axis of the ion confinement space, each fourth electrode comprising a fourth main portion extending from a first side of the ion confinement space to a second side of the ion confinement space, and a fourth edge portion located on the first side of the ion confinement space, wherein the fourth edge portion is wider than the fourth main portion along the longitudinal axis of the ion confinement space, and the first edge portion of the first electrode is positioned opposite the fourth edge portion of the fourth electrode, the first edge portion of the first electrode being positioned opposite the fourth edge portion of the fourth electrode, the first and third electrodes receiving a first RF voltage, and the second and fourth electrodes receiving a second RF voltage that is phase-shifted with respect to the first RF voltage. Example 21. The method according to Example 20, further comprising driving ions along the longitudinal axis of the ion confinement space. Example 22. The method according to Example 21, wherein driving ions along the longitudinal axis of the ion confinement space is a means of passing a carrier gas through the ion confinement space. Example 23. The method according to Example 21, wherein driving ions along the longitudinal axis of the ion confinement space includes applying a DC voltage to a plurality of electrodes to generate a DC gradient field or a DC traveling wave. Example 24. The method according to Example 21, wherein the RF voltage is configured to drive ions along the longitudinal axis of the ion confinement space. Example 25. The method according to Example 20, further comprising trapping ions in an ion confinement space. Example 26. Ion guide comprising: a first surface and a second surface facing each other with a gap between them; a plurality of electrodes including an array of first electrodes on the first surface and an array of second electrodes on the second surface, wherein the array of first electrodes and the array of second electrodes are positioned facing each other and define an ion confinement space within the gap; wherein the array of first electrodes comprises first and second electrodes alternately arranged on the first surface along the longitudinal axis of the ion confinement space; and the array of second electrodes comprises third and fourth electrodes alternately arranged on the second surface along the longitudinal axis of the ion confinement space; and the first and third electrodes are configured to receive RF voltages of the same phase. An ion guide is constructed such that the second and fourth electrodes are configured to receive RF voltages having the same phase and being phase-shifted with respect to the RF voltages received by the first and third electrodes, the main portions of the first and third electrodes and the main portions of the second and fourth electrodes are configured to generate a surface confinement electric field that suppresses the movement of ions in the ion confinement space toward the first and second surfaces, and the opposing edge portions of the first and fourth electrodes are configured to receive RF voltages that are phase-shifted with respect to each other and generate a first edge confinement electric field that suppresses the movement of ions in the ion confinement space toward the first side of the ion confinement space. Example 27. The ion guide according to Example 26, wherein the opposing edge portions of the second and third electrodes are configured to receive RF voltages that are phase-shifted relative to each other and generate a second edge-confinement electric field that suppresses the movement of ions toward the second side of the ion-confinement space within the ion-confinement space. Example 28. An ion guide according to Example 26, wherein additional opposing edge portions of the first and fourth electrodes generate a second edge-confinement electric field that suppresses the movement of ions in the ion-confinement space toward the second side of the ion-confinement space. Example 29. The ion guide according to Example 26, wherein each first electrode extends along the longitudinal axis of the ion confinement space to an adjacent second electrode, and each fourth electrode extends along the longitudinal axis of the ion confinement space to an adjacent third electrode. Example 30. The ion guide according to Example 26, wherein the first electrode and the fourth electrode have an L-shape, a T-shape, or a Y-shape. Example 31. The ion guide according to Example 26, wherein the first electrode and the fourth electrode have an LL shape, a TT shape, or a YY shape. Example 32. An ion guide comprising: a first surface and a second surface facing each other with a gap between them; a plurality of electrodes including an array of first electrodes on the first surface and an array of second electrodes on the second surface; and an ion confinement space in the gap between the array of first electrodes and the array of second electrodes, wherein the array of first electrodes comprises a first electrode and a second electrode arranged on the first surface along the longitudinal axis of the ion confinement space; the array of second electrodes comprises a third electrode and a fourth electrode arranged on the second surface along the longitudinal axis of the ion confinement space; and the first main portion of the first electrode is the third electrode An ion guide positioned opposite the third main portion of the electrode or the fourth main portion of the fourth electrode, with the second main portion of the second electrode positioned opposite the other of the third main portion of the electrode or the fourth main portion of the fourth electrode, with the first edge portion of the first electrode positioned opposite the fourth edge portion of the fourth electrode on the first side of the ion confinement space, the first electrode and the third electrode configured to receive an RF voltage, and the second electrode and the fourth electrode configured to receive an RF voltage that is phase-shifted with respect to the RF voltage received by the first electrode and the third electrode. Example 33. The ion guide according to Example 32, wherein the second edge portion of the second electrode is positioned opposite the third edge portion of the third electrode on the second side of the ion confinement space. Example 34. The ion guide according to Example 32, wherein the second edge portion of the first electrode is positioned opposite the third edge portion of the fourth electrode on the second side of the ion confinement space. Example 35. A method for fabricating an ion guide, comprising: arranging a first electrode and a second electrode in a first electrode arrangement on a first surface; arranging a third electrode and a fourth electrode in a second electrode arrangement on a second surface; and positioning the first surface facing the second surface with a gap between them such that the first electrode arrangement and the second electrode arrangement define an ion confinement space within the gap, wherein the first electrode arrangement and the second electrode arrangement are positioned such that the first main part of the first electrode is positioned opposite the third main part of the third electrode or the fourth main part of the fourth electrode. A method for fabricating an ion guide, comprising: positioning the second main portion of the second electrode opposite the other of the third main portion of the third electrode or the fourth main portion of the fourth electrode; positioning the first edge portion of the first electrode opposite the fourth edge portion of the fourth electrode on the first side of the ion confinement space; connecting the first electrode and the third electrode to a first circuit configured to receive an RF voltage; and connecting the second electrode and the fourth electrode to a second circuit configured to receive an RF voltage that is phase-shifted with respect to the RF voltage received by the first circuit. Example 36. The method according to Example 35, wherein the arrangement of the first electrode and the arrangement of the second electrode are further positioned such that the second edge portion of the second electrode is positioned opposite the third edge portion of the third electrode on the second side of the ion confinement space. Example 37. The method according to Example 35, wherein the arrangement of the first electrode and the arrangement of the second electrode are further positioned such that the second edge portion of the first electrode is positioned opposite the third edge portion of the fourth electrode on the second side of the ion confinement space. Example 38. An ion guide comprising a plurality of electrodes arranged on opposing surfaces and defining an ion confinement space in the gap between the opposing surfaces, wherein each electrode comprises an elongated main portion and an edge portion at the end of the main portion, the edge portion being wider than the main portion along the longitudinal axis of the ion confinement space, the plurality of electrodes being configured to receive an RF voltage, and the plurality of electrodes being arranged to receive an RF voltage in which the opposing edge portions are phase-shifted relative to each other. Example 39. The ion guide according to Example 38, wherein multiple electrodes are arranged such that opposing main portions receive RF voltages of the same phase. Example 40. The ion guide described in Example 38, wherein the multiple electrodes are arranged such that opposing main portions do not receive RF voltages of the same phase.

Claims

1. It is an ion guide, A first surface and a second surface facing each other with a gap in between, A plurality of electrodes comprising a first electrode array on a first surface and a second electrode array on a second surface, wherein the first electrode array and the second electrode array are positioned facing each other and define an ion confinement space within the gap between them, The arrangement of the first electrodes comprises a first electrode and a second electrode arranged on the first surface along the longitudinal axis of the ion confinement space, Each first electrode is A first main portion extending from the first side of the ion confinement space to the second side of the ion confinement space, A first edge portion located on the first side of the ion confinement space, wherein the first edge portion is wider than the first main portion along the longitudinal axis of the ion confinement space, The arrangement of the second electrode comprises a third electrode and a fourth electrode arranged on the second surface along the longitudinal axis of the ion confinement space, Each of the fourth electrodes, A fourth main portion extending from the first side of the ion confinement space to the second side of the ion confinement space, A fourth edge portion located on the first side of the ion confinement space, wherein the fourth edge portion is wider than the fourth main portion along the longitudinal axis of the ion confinement space, The first edge portion of the first electrode is positioned opposite the fourth edge portion of the fourth electrode, An ion guide in which the first electrode and the third electrode are configured to receive a first RF voltage, and the second electrode and the fourth electrode are configured to receive a second RF voltage that is phase-shifted with respect to the first RF voltage.

2. The ion guide according to claim 1, wherein the first electrode and the second electrode have an L-shape, a T-shape, or a Y-shape.

3. Each third electrode comprises a third main portion, The ion guide according to claim 1, wherein the first main portion of the first electrode is positioned opposite the third main portion of the third electrode.

4. The ion guide according to claim 1, wherein the first main portion of the first electrode is positioned opposite the fourth main portion of the fourth electrode.

5. Each second electrode comprises a second main portion, Each third electrode comprises a third main portion, The ion guide according to claim 1, wherein the first main portion of the first electrode and the second main portion of the second electrode are positioned opposite the gap between the third main portion of the third electrode and the fourth main portion of the fourth electrode.

6. Each second electrode A second main portion extending from the first side of the ion confinement space to the second side of the ion confinement space, A second edge portion located on the second side of the ion confinement space, wherein the second edge portion is wider than the second main portion along the longitudinal axis of the ion confinement space, Each third electrode A third main portion extending from the first side of the ion confinement space to the second side of the ion confinement space, A third edge portion located on the second side of the ion confinement space, wherein the third edge portion is wider than the third main portion along the longitudinal axis of the ion confinement space, The ion guide according to claim 1, wherein the second edge portion of the second electrode is positioned opposite the third edge portion of the third electrode.

7. The ion guide according to claim 6, wherein the second electrode and the third electrode have an L-shape, a T-shape, or a Y-shape.

8. Each first electrode further comprises a second edge portion on the second side of the ion confinement space, the second edge portion being wider than the first main portion along the longitudinal axis of the ion confinement space. Each fourth electrode further comprises a third edge portion on the second side of the ion confinement space, the third edge portion being wider than the fourth main portion along the longitudinal axis of the ion confinement space, The ion guide according to claim 1, wherein the second edge portion of the first electrode is positioned opposite the third edge portion of the fourth electrode.

9. The ion guide according to claim 8, wherein the first electrode and the fourth electrode have an LL shape, a TT shape, or a YY shape.

10. Each second electrode has a second main portion, The ion guide according to claim 1, wherein the first edge portion of the first electrode extends along the longitudinal axis of the ion confinement space beyond all or part of the second main portion of an adjacent second electrode.

11. Each third electrode has a third main portion, The ion guide according to claim 10, wherein the fourth edge portion of the fourth electrode extends along the longitudinal axis of the ion confinement space beyond all or part of the third main portion of an adjacent third electrode.

12. The ion guide according to claim 1, wherein one or both of the first surface and the second surface are provided with a printed circuit board (PCB).

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