A variable pitch double helix ion electrode and guide

Abstract

The present application belongs to the technical field of ion electrodes, and more specifically, relates to a variable pitch double helix ion electrode and a guide; comprising a first helical electrode and a second helical electrode with overlapping axes, the first helical electrode and the second helical electrode being symmetrically rotated 180 degrees with the axis as the rotation axis, and the spiral diameters of the first helical electrode and the second helical electrode being constant; the pitch of the first helical electrode and the second helical electrode gradually decreases from one end to the other end, thereby realizing radial confinement and axial drive of ions; the variable pitch double helix ion electrode of the present invention can simultaneously form a steep radial equivalent potential and a gently changing axial equivalent when applying a radio frequency voltage, so the variable pitch double helix ion electrode proposed in the present invention can simultaneously provide an electric field for radial confinement and axial focusing of ions.

Description

Technical Field

[0001] The present application belongs to the technical field of ion electrodes, and more specifically, relates to a variable pitch double-helix ion electrode and a guide. Background Art

[0002] Mass spectrometry aims to identify chemical compounds by analyzing the molecular or atomic masses of their components. This process involves ionizing neutral species and performing mass-to-charge ratio (m / z) analysis using electric or magnetic fields in a high vacuum. In modern organic mass spectrometry, samples are usually ionized at atmospheric pressure. The ions need to pass through multiple chambers with gradient gas pressures to reach the mass analyzer in a high vacuum. Since these chambers are usually interconnected by flow-restricting orifices (about 1 mm in diameter) to limit gas conduction and maintain vacuum, an effective ion confinement method is essential to maintain ion transmission rate and instrument sensitivity.

[0003] RF ion guides are often used to achieve effective ion confinement under high pressure (>100 Pa) and medium pressure (1-100 Pa) conditions. The motion of ions in the RF electric field can be analyzed by the pseudopotential model. In this model, the RF electric field is equivalently converted into a DC potential. Stacked ring ion guides and multipole ion guides are the two most commonly used RF ion guides.

[0004] Stacked ring ion guides are usually composed of metal sheets arranged in sequence, with RF voltages of opposite phases applied to adjacent metal sheets. These structures can provide strong radial confinement for ions of various mass-to-charge ratios. However, their segmented design will produce axial potential wells, hindering the radial transport of ions and causing mass discrimination effects. To solve this problem, gradient DC voltage or DC traveling wave voltage can be applied to the electrodes of the stacked ring ion guide, but this will greatly increase the complexity of the hardware.

[0005] The multipole ion guide consists of multiple metal rods. Adjacent metal rods are applied with RF voltages of different phases. Each metal rod is processed into a specific cross-sectional shape and arranged symmetrically around the central axis. Usually, the number of metal rods (order) is an even number, and common configurations include 4, 6 or 8 metal rods. The higher the order, the larger the ion receiving space range.

[0006] Multipole ion guides are generally used in the next vacuum stage of atmospheric pressure interfaces, collision cells in triple quadrupole mass spectrometers (QqQ-MS), drift tubes in proton transfer reaction mass spectrometers (PTR-MS), and linear quadrupole ion trap mass spectrometers (LTQ-MS). The device is characterized by a collision focusing effect, that is, ions are cooled by a buffer gas and focused near the axis to form an ion beam with low energy and narrow velocity distribution. However, due to the lack of axial propulsion means, ions (especially low-mass ions) can easily stop in the ion guide, and axial drive needs to be applied to the ions. One of the common ways to achieve axial ion propulsion is to segment the electrodes. In this design, the electrodes of the multipole ion guide are segmented, and a gradient DC voltage is added to them to form an axial field. Although this method can effectively achieve ion drive, its hardware complexity is high and it is easy to reduce the ion mass-to-charge ratio transmission bandwidth. Summary of the invention

[0007] The present invention provides a variable pitch double helix ion electrode and a guide, which are intended to realize radial confinement and axial drive of ions simultaneously by using radio frequency excitation.

[0008] A variable pitch double helical ion electrode, comprising a first helical electrode and a second helical electrode whose axes coincide with each other, the first helical electrode and the second helical electrode being symmetrically rotated 180 degrees with the axis as the rotation axis, and the helical diameters of the first helical electrode and the second helical electrode being constant;

[0009] The pitch of the first spiral electrode and the second spiral electrode gradually decreases from one end to the other end, thereby achieving radial confinement and axial drive of ions.

[0010] The variable pitch double helix ion electrode of the present invention can simultaneously form a steep radial equivalent potential and a gently changing axial equivalent potential when a radio frequency voltage is applied. Therefore, the variable pitch double helix ion electrode proposed by the present invention can simultaneously provide an electric field for radial confinement and axial focusing of ions.

[0011] Preferably, the first spiral electrode and the second spiral electrode are continuous or discrete spirals.

[0012] Preferably, the spiral cross-sections of the first spiral electrode and the second spiral electrode are axisymmetric or centrosymmetric cross-sections, and the cross-sectional area is 0.1-40000 mm².

[0013] Preferably, the pitch of the first spiral electrode and the second spiral electrode varies in the range of 1-50 mm.

[0014] Preferably, the spiral angles of the first spiral electrode and the second spiral electrode are 0.01-85 degrees, and the inner diameters of the first spiral electrode and the second spiral electrode are 0.2-200 mm.

[0015] Preferably, both the first spiral electrode and the second spiral electrode are spiral electrodes formed by a plurality of electrode sheets;

[0016] The electrode sheet is formed by the cross section of the spiral body. Different pitches of the spiral body are equivalently converted into different center angles, and the corresponding cross section of the spiral body is cut to form the electrode sheet.

[0017] On the other hand, the present invention provides a variable pitch double helix ion guide, wherein the ion electrode in the guide adopts a variable pitch double helix ion electrode described in the present invention; the details are as follows:

[0018] A variable pitch double helix ion guide comprises a variable pitch double helix electrode to which a reverse radio frequency voltage is applied, an electrode fixing bracket, and an ion introduction electrode and an ion extraction electrode;

[0019] The variable pitch double helical electrode adopts a variable pitch double helical ion electrode described in the present invention;

[0020] The variable pitch double helical electrode is installed between the ion introduction electrode and the ion extraction electrode, and the pitch of the variable pitch double helical electrode gradually decreases from the ion introduction electrode to the ion extraction electrode; wherein the ion introduction electrode and the ion extraction electrode each have a through hole, and the two through holes are coaxial and have the same diameter;

[0021] The electrode fixing bracket is installed between the ion introduction electrode and the ion extraction electrode, and is used to fix the variable pitch double helical electrode;

[0022] The working air pressure of the guide is not greater than 10Pa.

[0023] A variable pitch double helix ion guide comprises a variable pitch double helix electrode and a plurality of printed circuit boards arranged in sequence;

[0024] The variable pitch double helical electrode adopts a variable pitch double helical ion electrode described in the present invention;

[0025] The printed circuit boards are each provided with a through hole for mounting the variable pitch double helix ion electrode; a pair of electrode sheets of the variable pitch double helix ion electrode is mounted in each of the through holes, wherein the pair of electrode sheets mounted in the same printed circuit board through hole adopts a pair of mutually insulated copper clad layers.

[0026] Preferably, it comprises a plurality of positioning rods, each positioning rod passes through a plurality of sequentially arranged printed circuit boards and is assembled with the printed circuit boards, wherein an insulating gasket is arranged between each printed circuit board.

[0027] The beneficial effects of the present invention include:

[0028] The variable pitch double helix ion electrode of the present invention can simultaneously form a steep radial equivalent potential and a gently changing axial equivalent potential when a radio frequency voltage is applied. Therefore, the variable pitch double helix ion electrode proposed by the present invention can simultaneously provide an electric field for radial confinement and axial focusing of ions.

[0029] Secondly, the present invention adopts an electrode sheet to form the spiral electrode, which greatly reduces the manufacturing difficulty, reduces the hardware complexity and the system cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 A continuously variable pitch double-helix ion electrode is provided in an embodiment of the present invention.

[0032] Figure 2 A discrete variable pitch double-helix ion electrode is provided in an embodiment of the present invention.

[0033] Figure 3 The discrete process of the continuously variable pitch double-helix ion electrode provided by the embodiment of the present invention.

[0034] Figure 4 A continuously variable pitch double-helix ion guide is provided in an embodiment of the present invention.

[0035] Figure 5 The working principle of the variable pitch double helix ion guide provided in the embodiment of the present invention is described.

[0036] Figure 6 The numerical simulation results of the axial distribution of the equivalent electric field of a variable pitch double-helix electrode provided by the embodiment of the present invention.

[0037] Figure 7 Numerical simulation results of the radial distribution of the equivalent electric field of double-helix electrodes with different pitches provided in the embodiments of the present invention.

[0038] Figure 8 A discrete variable pitch double-helix ion guide is provided in an embodiment of the present invention.

[0039] Fig. 9 A schematic diagram of the effect of a discrete variable pitch double-helix ion electrode provided in an embodiment of the present invention.

[0040] Explanation of reference numerals: 1. first spiral electrode; 2. second spiral electrode; 3. ion introduction electrode; 4. ion extraction electrode; 5. radio frequency power supply; 6. printed circuit board; 7. electrode sheet; 8. electrode fixing bracket; 9. positioning hole. DETAILED DESCRIPTION

[0041] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0042] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0043] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0045] Example 1

[0046] See attached Figure 1 As shown, a variable pitch double helical ion electrode comprises a first helical electrode 1 and a second helical electrode 2 whose axes coincide with each other, the first helical electrode 1 and the second helical electrode 2 are symmetrically rotated 180 degrees with the axis as the rotation axis, and the helical diameters of the first helical electrode 1 and the second helical electrode 2 are constant;

[0047] The pitch of the first spiral electrode 1 and the second spiral electrode 2 gradually decreases from one end to the other end, thereby achieving radial confinement and axial drive of ions.

[0048] The first spiral electrode 1 and the second spiral electrode 2 are continuous and uninterrupted spirals.

[0049] The cross-section of the spiral body of the first spiral electrode 1 and the second spiral electrode 2 is an axisymmetric or centrosymmetric cross-section (for example: fan ring, sector, circle, rectangle, etc.), and the cross-sectional area is 0.1-40000mm²; in this embodiment, the cross-section of the spiral body of the first spiral electrode 1 and the second spiral electrode 2 is a circle.

[0050] The pitch of the first spiral electrode 1 and the second spiral electrode 2 varies in the range of 1-50 mm;

[0051] The spiral angle of the first spiral electrode 1 and the second spiral electrode 2 is 0.01-85 degrees, and the inner diameter of the first spiral electrode 1 and the second spiral electrode 2 is 0.2-200 mm.

[0052] Example 2

[0053] See attached Figure 2 As shown, the difference between this embodiment and embodiment 1 is that the first spiral electrode 1 and the second spiral electrode 2 use electrode sheets 7, which are specifically as follows:

[0054] Referring to the shape of the electrode sheet 7 described in the embodiment, if the cross-sections of the spiral bodies of the first spiral electrode 1 and the second spiral electrode 2 are both circular, then Figure 3 As shown, we convert the different pitches of the spiral into different center angles, cut the corresponding spiral cross section, and form the electrode sheet 7. Figure 3 RF+ and RF- respectively represent the first spiral electrode 1 and the second spiral electrode 2, based on the description of Example 1 and Figure 3 It can be seen that there are two electrode sheets 7 with the same geometric shape in one cross section, namely the electrode sheets 7 of the first spiral electrode 1 and the second spiral electrode 2; and through Figure 3 It can be seen that as the pitch gradually increases, the smaller the cross-section of the spiral body is, the smaller the electrode sheet 7 formed will be.

[0055] The description of converting different pitches of the spiral into different center angles and intercepting corresponding spiral cross sections to form the electrode sheet 7 is as follows:

[0056] See also Figure 3 As shown, we cut the corresponding cross section after rotating the spiral body by a corresponding angle, and the rotation angles corresponding to different pitches are different. For example, when the pitch is 3 mm, our central angle is 120 degrees; that is to say, when the axial distance between two adjacent teeth on the spiral line of the spiral body is 3 mm, it is decomposed into an electrode sheet 7 with an end-to-end arrangement of an angle of 120° and a thickness of 1 mm.

[0057] The electric field distribution characteristics of the continuous model and discrete model of the variable pitch double helix electrode are compared based on numerical simulation. The cross-sectional equivalent potential distribution of the continuous model and the discrete model is obtained by simulation as follows: Fig. 9 As shown; Fig. 9 The upper middle part shows the equivalent potential distribution of the continuous model; this result shows that an equivalent potential gradient that can realize ion axial driving and an equivalent potential channel that can realize ion confinement are indeed generated inside the electrode; Fig. 9 The lower part shows the equivalent potential distribution of the discrete model, and the basic distribution law of the electric field is consistent with that of the continuous model. Therefore, the discrete model and the continuous model are equivalent in principle, that is, the structure of the first spiral electrode 1 and the second spiral electrode 2 of the discrete model adopted in this embodiment can also provide electric fields for radial confinement and axial focusing of ions at the same time.

[0058] See also Figure 3 The figure shows the discrete process of the continuous variable pitch double helix electrode. First, the radial cross-section of the continuous double helix electrode with different pitches (2.5 mm, 10 mm and 20 mm) is intercepted. It can be observed that when the pitch is close to 0 mm, the effective area of ​​the cross-section is closer to the ring area, and as the pitch increases, the ratio of the effective area of ​​the cross-section to the ring area decreases. Therefore, different pitches can be equivalently converted into fan rings with different central angles; the problem of uniform gradient pitch is simplified to the ratio problem of uniform gradient arc electrodes, which greatly reduces the manufacturing difficulty.

[0059] Example 3

[0060] A variable pitch double helix ion guide, using the variable pitch double helix ion electrode described in Example 1;

[0061] The variable pitch double helix ion guide comprises a variable pitch double helix ion electrode, two electrode fixing brackets 8, an ion introduction electrode 3 and an ion extraction electrode 4;

[0062] The variable pitch double helical electrode is installed between the ion introduction electrode 3 and the ion extraction electrode 4, and the pitch of the variable pitch double helical electrode gradually decreases from the ion introduction electrode 3 to the ion extraction electrode 4; wherein the ion introduction electrode 3 and the ion extraction electrode 4 each have a through hole, and the two through holes are coaxial and have the same diameter;

[0063] The electrode fixing bracket 8 is installed between the ion introduction electrode 3 and the ion extraction electrode 4, and is used to fix the variable pitch double helical electrode; wherein two electrode fixing brackets 8 are installed on the outer circumferential surface of the variable pitch double helical ion electrode, and the two electrode fixing brackets 8 are installed on the outer circumferential surface of the variable pitch double helical ion electrode at an interval of 180 degrees;

[0064] See also Figure 4 As shown, the variable pitch double helix ion guide has a length of 60 mm, an electrode spiral diameter of 6 mm, a wire diameter of 1.5 mm, and a pitch variation range of 3-9 mm; when the variable pitch double helix ion guide is working, the two ends of its ion introduction limiting hole (the through hole set on the above-mentioned ion introduction electrode 3) are respectively connected to the inside of the ion guide and the rough vacuum stage; the tail of the variable pitch double helix ion guide is provided with an ion extraction port (that is, the through hole of the above-mentioned ion extraction electrode 4) connected to the next level of vacuum; when the vacuum pump is working, the absolute gas pressure inside the guide is ensured to be no more than 10 Pa; the voltage amplitude applied to the spiral electrode is 100-400V (peak-to-peak), the frequency is 1-2MHz, and the phase difference is 180 degrees; in this embodiment, the material of the limiting hole is 304 stainless steel, the material of the bracket is polytetrafluoroethylene, and the material of the double helix electrode is brass.

[0065] The specific description of the electric field that can achieve radial confinement and axial focusing of ions in the embodiment is as follows:

[0066] For RF ion guides, when the RF frequency (ω) is high enough, the oscillation of ions in it can be expressed as long-term motion and described using the equivalent potential theory, which is expressed as:

[0067] (1)

[0068] in is the strength of the equivalent electric potential, is the charge of the ion, is the electric field strength, is the ion mass, ω is the radio frequency;

[0069] In this embodiment (this comment is also applicable to Example 1), when ions move in the RF electric field, they have potential energy provided by the equivalent electric potential field; the cross-section of the stacked ring RF ion guide can be represented as a dipole array or an infinitely high-order multipole field; in the stacked ring RF ion guide, RF voltages with opposite phases are applied to adjacent electrodes in the array; for a dipole array with a gradient spacing, a series of axial potential wells with different depths (i.e., equivalent potentials) are generated; the difference in the axial potential wells is understood by the similarity principle, in Figure 5 In the figure, points m1 and m2 are aligned with the centers of the two motors and form a certain angle (θ) with the adjacent electrodes; since the geometric scales of points m1 and m2 are similar, the effective potentials of the two points will also be similar and are designated as invariant points; for these two invariant points, the electrode spacing ( d 1 and d 2 ), the distances from the two invariant points to the central axis are marked as h1 and h 2 ; Obviously, when d 1 < d 2 hour, h 2 < h 1 Always holds true; according to the spatial distribution pattern of the effective potential of the stacked ring ion guide (such as Figure 5 As shown in the figure, the potential of the point closer to the electrode is higher; as the distance d increases, the invariant point approaches the central axis, resulting in an increase in potential; therefore, the gradient electrode spacing in the stacked ring ion guide produces axial potential wells of different depths; in a double helix electrode with a continuous electrode shape, the gradient spacing will still produce equivalent potentials of different sizes, but the equivalent potential distribution has a continuous feature, as shown in the figure. Figure 6 As shown in , the pitch size is positively correlated with the axial equivalent potential height; Figure 1 and Figure 7 As shown, applying RF voltage to the guide used in this embodiment through the RF power supply 5 can simultaneously form a steep radial equivalent potential and a gently changing axial equivalent potential; the above results show that the variable pitch double helix electrode can indeed provide an electric field for ion radial confinement and axial focusing at the same time.

[0070] Example 4

[0071] See also Figure 8 As shown, a variable pitch double helix ion guide adopts a variable pitch double helix ion electrode described in Example 2;

[0072] The variable pitch double helical electrode adopts a variable pitch double helical ion electrode described in the present invention;

[0073] The printed circuit board 6 is provided with a through hole for installing the variable pitch double helix ion electrode; a pair of electrode sheets 7 of the variable pitch double helix ion electrode is installed in each of the through holes, wherein the pair of electrode sheets 7 installed in the same through hole of the printed circuit board 6 adopts a pair of mutually insulated copper clad layers.

[0074] The length of the variable pitch double helix ion guide is 60 mm, the equivalent helix diameter is 6 mm, and the equivalent pitch variation range is 3-9 mm; when the vacuum pump is working, the absolute gas pressure inside the variable pitch double helix ion guide is ensured to be no more than 10 Pa; the voltage amplitude applied to each electrode copper clad layer is 100-400V (peak-to-peak value), the frequency is 1-2MHz, and the phase difference is 180 degrees; four positioning holes 9 are arranged on each printed circuit board 6, and positioning rods are installed in the positioning holes 9 to ensure the radial installation accuracy of each electrode sheet 7; insulating gaskets are arranged between each printed circuit board 6 to ensure its axial installation accuracy.

[0075] In this embodiment, it should be noted that the interval between two adjacent printed circuit boards 6 is set according to the interval between two adjacent pairs of electrode sheets 7; as mentioned in Example 2, the different pitches of the spiral are equivalently converted into different center angles, and the corresponding spiral cross-sections are intercepted; therefore, we form corresponding pairs of electrode sheets 7 according to the spiral cross-sections intercepted at the angle; all pairs of electrode sheets 7 are intercepted according to this principle; at this time, the interval between adjacent pairs of electrode sheets 7 is already fixed, and a pair of electrode sheets 7 are installed on each printed circuit board 6, so the interval between two adjacent printed circuit boards 6 is determined based on the two adjacent electrode sheets 7.

[0076] In this embodiment (this comment is also applicable to Embodiment 2), the different pitches of the helix are equivalently converted into different center angles, and the corresponding cross-sections of the helix are intercepted, which greatly reduces the manufacturing difficulty; and the structure of the printed circuit board 6 adopted greatly reduces the manufacturing difficulty of the entire device, and the structure is simple, which is easy to manufacture and install.

[0077] Embodiments 3 and 4 provided in the present invention are not limitations of the present invention, but are merely exemplary technical solutions. The discrete variable pitch double helix ion electrode of embodiment 2 can also be applied to the structure described in embodiment 3, by replacing the continuous variable pitch double helix ion electrode in embodiment 3 with a discrete variable pitch double helix ion electrode; similarly, the discrete variable pitch double helix ion electrode in embodiment 4 can also be replaced with a continuous variable pitch double helix ion electrode, wherein the electrode sheet 7 corresponds to the helix corresponding to each turn of the coil.

[0078] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A variable pitch double helix ion electrode, characterized in that: It comprises a first spiral electrode and a second spiral electrode whose axes coincide with each other, the first spiral electrode and the second spiral electrode are symmetrically rotated 180 degrees with the axis as the rotation axis, and the spiral diameters of the first spiral electrode and the second spiral electrode are constant; The pitch of the first spiral electrode and the second spiral electrode gradually decreases from one end to the other end, thereby achieving radial confinement and axial drive of ions.

2. A variable pitch double helix ion electrode according to claim 1, characterized in that: The first spiral electrode and the second spiral electrode are continuous or discrete spiral bodies.

3. A variable pitch double helix ion electrode according to claim 2, characterized in that: The spiral cross-section of the first spiral electrode and the second spiral electrode is an axisymmetric or centrosymmetric cross-section, and the cross-sectional area is 0.1-40000 mm².

4. The variable pitch double helical ion electrode according to claim 3, characterized in that: The pitch of the first spiral electrode and the second spiral electrode varies in the range of 1-50 mm.

5. A variable pitch double helical ion electrode according to claim 4, characterized in that: The spiral angle of the first spiral electrode and the second spiral electrode is 0.01-85 degrees, and the inner diameter of the first spiral electrode and the second spiral electrode is 0.2-200 mm.

6. The variable pitch double helical ion electrode according to claim 1, characterized in that: The first spiral electrode and the second spiral electrode are both spiral electrodes formed by a plurality of electrode sheets; The electrode sheet is formed by the cross section of the spiral body. Different pitches of the spiral body are equivalently converted into different center angles, and the corresponding cross section of the spiral body is cut to form the electrode sheet.

7. A variable pitch double helix ion guide, characterized in that: A variable pitch double helix ion electrode as described in any one of claims 1 to 6 is used as the ion electrode of the guide, and the working gas pressure of the guide is not greater than 10Pa.

8. The variable pitch double helix ion guide according to claim 7, characterized in that: The guide includes a variable pitch double helical electrode for applying reverse radio frequency voltage, an electrode fixing bracket, and an ion introduction electrode and an ion extraction electrode; The variable pitch double helical electrode is installed between the ion introduction electrode and the ion extraction electrode, and the pitch of the variable pitch double helical electrode gradually decreases from the ion introduction electrode to the ion extraction electrode; wherein the ion introduction electrode and the ion extraction electrode each have a through hole, and the two through holes are coaxial and have the same diameter; The electrode fixing bracket is installed between the ion introduction electrode and the ion extraction electrode, and is used to fix the variable pitch double helical electrode.

9. The variable pitch double helix ion guide according to claim 7, characterized in that: The guide comprises a variable pitch double helical electrode and a plurality of printed circuit boards arranged in sequence; The printed circuit boards are each provided with a through hole for mounting the variable pitch double helix ion electrode; a pair of electrode sheets of the variable pitch double helix ion electrode is mounted in each of the through holes, wherein the pair of electrode sheets mounted in the same printed circuit board through hole adopts a pair of mutually insulated copper clad layers.

10. The variable pitch double helix ion guide according to claim 9, characterized in that: It comprises a plurality of positioning rods, each of which penetrates through a plurality of printed circuit boards arranged in sequence and is assembled with the printed circuit boards, wherein insulating gaskets are arranged between each printed circuit board.

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