Multi-section linear ion trap device and processing technology thereof

Abstract

The invention discloses a multi-section linear ion trap device and a processing technology thereof, and relates to the technical field of linear ion traps, the multi-section linear ion trap device comprises a mounting bracket and a quadrupole rod group, the quadrupole rod group can be mounted in the mounting bracket, and a plurality of limiting elements are arranged on the inner wall of the mounting bracket; each limiting element corresponds to each to-be-cut position of the quadrupole rod group, after the quadrupole rod group is cut along each limiting element, a plurality of sections of cutting rod units can be formed, an insulating gap is formed between every two adjacent cutting rod units, and voltage is independently applied to each section of cutting rod unit; or each section of the cutting rod unit is powered up by adopting a resistor and a capacitor for voltage division. According to the invention, the assembly precision can be improved while the processing difficulty is reduced, the uniformity of axial potential in an ion trap transmission system is ensured, the ion transmission efficiency is improved, and the kinetic energy dispersion of extracted ions is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of linear ion traps, and in particular to a multi-segment linear ion trap device and its processing technology. Background Art

[0002] A linear ion trap (Linear Ion Trap, LIT) is a device with a quadrupole as the core that can trap ions. The quadrupole consists of four accurately parallel rods with a DC voltage (DC) and a superimposed RF voltage (RF). A pair of opposite electrodes is in-phase, while the phases of the two pairs of electrodes are opposite. When a group of ions with different mass-to-charge ratios enter the electric field composed of DC and RF along the axial direction of the parallel rods, only the ions that meet specific conditions can pass through the quadrupole stably by oscillating. Therefore, by controlling different voltage conditions, the quadrupole can be used as a transmission cooling device or a mass analyzer.

[0003] A linear ion trap is a commonly used mass analyzer that relies on the combination of RF voltage and DC voltage to capture and separate ions. The RF voltage generates a dynamic electric field between the quadrupoles to capture ions in the x and y directions, while the DC component is a fixed voltage applied to further optimize the electric field shape and help improve the ion capture efficiency and stability. During the mass spectrometry scan, the linear ion trap detects different ions in the order of mass-to-charge ratio by scanning lines to achieve mass analysis. This working mechanism based on DC component adjustment and scan line control enables the linear ion trap to have high sensitivity and multi-stage mass spectrometry (MSn) capabilities and is widely used in the analysis of complex samples.

[0004] When the linear ion trap is used as a transmission cooling device, RF is applied to the quadrupoles to radially confine the ions. To achieve better transmission and cooling effects, an inert gas is introduced into the ion trap at the same time to make it collide fully with the ions, thereby reducing the energy of the ions to achieve the effect of cooling and focusing. However, this may also cause the ions to be trapped in the ion trap due to low axial energy and unable to move forward and reach the rear detector. Therefore, an additional DC bias needs to be applied to the quadrupoles to provide axial kinetic energy for the ions, so that the ions are not always trapped in the trap after sufficient cooling.

[0005] In the prior art, there are various ways to provide axial kinetic energy for ions. However, in actual use, there are often problems such as too long field-free regions in multi-segment quadrupoles, resulting in some ions being trapped in the rods and unable to be extracted, causing ion loss and reducing the transmission efficiency. At the same time, due to the segmented structure, there is a certain voltage difference in the DC of different segments of the quadrupoles, which easily leads to voltage mutations between the rods and also affects the energy dispersion of the ions to a certain extent.

[0006] In the prior art, there is also a way to electrically segment the quadrupole by coating a conductive layer on an insulating rod, controlling the voltage of each segment of the quadrupole, applying different DC voltages to different segments, so that different segments of the multipole have different potential differences axially, and a potential gradient can be formed axially. However, new problems have arisen. Mechanically, the processing and assembly of the segmented quadrupole have always affected the ion transmission efficiency. The multi-segment quadrupole has high requirements for assembly accuracy. The conventional processing and assembly methods are to separately process the insulating material and the metal rod and then assemble them by superimposing and nesting. And due to the multi-segment structure, there are certain gaps between each rod and between the insulating material and the metal rod. This processing method requires a long time to correct during assembly, is prone to micron-level errors, and the problem of non-concentricity occurs. That is, the above design only segments the quadrupole electrically, but mechanically the quadrupole is still an integral body. And because the conductive layer is thin, it is easy to be scratched during assembly. If the surface of each conductive layer is uneven, it is also easy to cause voltage mutation, affecting the transmission efficiency. Therefore, the processing accuracy requirements for the conductive layer are high. Summary of the Invention

[0007] The object of the present invention is to provide a multi-segment linear ion trap device and its processing technology to solve the problems existing in the above prior art, reduce the processing difficulty while improving the assembly accuracy, ensure the uniformity of the axial potential in the ion trap transmission system, improve the ion transmission efficiency, and reduce the kinetic energy dispersion of the extracted ions.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] The present invention provides a multi-segment linear ion trap device, including a mounting bracket and a quadrupole rod group. The quadrupole rod group can be installed in the mounting bracket, and a plurality of limiting elements are provided on the inner wall of the mounting bracket. Each of the limiting elements corresponds to each cutting position of the quadrupole rod group. After cutting the quadrupole rod group along each of the limiting elements, a plurality of cut rod units can be formed, and an insulating gap is formed between adjacent cut rod units. Each segment of the cut rod unit is applied with voltage separately, or each segment of the cut rod unit is powered by resistor-capacitor voltage division.

[0010] In an embodiment, the mounting bracket includes four mounting plates. The four mounting plates can enclose to form a cuboid with a hollow interior and two open ends. The quadrupole rod group includes four parallel rods, and the four parallel rods are respectively fixed to each of the mounting plates. A plurality of the limiting elements are provided on each of the mounting plates. The limiting elements located on the same mounting plate are arranged in sequence along the length direction of the parallel rod, and the positions of the limiting elements located on different mounting plates correspond to each other.

[0011] In one embodiment, the four parallel rods are independently arranged, or two of the four parallel rods are fixed together as a unit, or all four parallel rods are fixed together as a unit.

[0012] In one embodiment, there are at least two of the limiting elements on each of the mounting plates.

[0013] In one embodiment, the limiting element is a limiting protrusion protruding from the inner wall of the mounting bracket towards the center of the mounting bracket.

[0014] In one embodiment, the quadrupole rod group is welded to the inner wall of the mounting bracket.

[0015] In one embodiment, the mounting bracket is made of an insulating and non-outgassing material.

[0016] In one embodiment, the quadrupole rod group is made of a conductive metal material.

[0017] The present invention also discloses a processing technology for a multi-segment linear ion trap device according to any one of the above technical solutions, including the following steps:

[0018] S1. Process and fabricate each mounting plate of the mounting bracket and each parallel rod of the quadrupole rod group, and set a corresponding number of limiting elements on one side of each mounting plate according to the number of required rod units to be cut, and respectively fix each parallel rod on the side of the mounting plate where the limiting element is provided;

[0019] S2. Cut each parallel rod along the position where the limiting element is located, and make each parallel rod respectively form a plurality of spaced-apart cutting rod units;

[0020] S3. Surround a cuboid with the mounting plates so that the cutting rod units corresponding in position are arranged in a rectangle, and form an ion channel inside the whole formed by the mounting plates and the cutting rod units;

[0021] S4. The cutting rod units on each mounting plate are located in the same plane, and an electric current is applied to each cutting rod unit to form an electric field required for ion transmission.

[0022] In one embodiment, in S1, when fabricating the mounting bracket, first fabricate a mounting plate blank, press the raw material blank with a mold, and after sintering and forming the mounting plate blank, preliminarily press a limiting protrusion on the mounting plate blank, and the positions of the limiting protrusions on multiple mounting plates correspond to each other.

[0023] The present invention has achieved the following technical effects compared with the prior art:

[0024] The multi-segment linear ion trap device and its processing technology provided by the present invention include a mounting bracket and a quadrupole rod group. The quadrupole rod group can be installed in the mounting bracket, and a number of limiting elements are provided on the inner wall of the mounting bracket. Each limiting element corresponds to each cutting position of the quadrupole rod group. After cutting the quadrupole rod group along each limiting element, a multi-segment cutting rod unit can be formed. During cutting, since the mounting bracket and the quadrupole rod group are first connected and fixed before cutting, there is no assembly error between the mounting bracket and the quadrupole rod group, which can avoid the non-concentric problem during assembly caused by traditional cutting first and then assembly, greatly improving the assembly accuracy and meeting the design of the multi-segment linear ion trap device. At the same time, when ions enter each segment of the cutting rod unit in sequence, they can collide with inert gas to reduce the energy of the ions so as to achieve the effect of cooling and focusing. An insulating gap is formed between adjacent cutting rod units to keep each segment of the cutting rod unit mechanically and electrically separated. Each segment of the cutting rod unit is applied with voltage separately, or each segment of the cutting rod unit is powered by resistance-capacitance voltage division, so that different potential differences can be formed in different sections of the entire multi-segment linear ion trap device in the axial direction, and thus a more uniform axial potential gradient can be formed in the axial direction, improving the transmission efficiency and effectively reducing the influence of velocity dispersion caused by the reduction of the axial kinetic energy velocity of ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is a schematic structural diagram of the multi-segment linear ion trap device before cutting in Embodiment 1;

[0027] Figure 2 It is a partial cross-sectional view of the multi-segment linear ion trap device before cutting in Embodiment 1;

[0028] Figure 3 It is a schematic structural diagram of the parallel rods before cutting in Embodiment 1;

[0029] Figure 4 It is a partial structural diagram of the mounting plate in Embodiment 1;

[0030] Figure 5 It is a connection diagram of the mounting plate and the parallel rods in Embodiment 1 (the parallel rods are cut into four segments);

[0031] Figure 6 It is a connection diagram of the mounting plate and the parallel rods in Embodiment 1 (the parallel rods are cut into six segments);

[0032] In the figure: 1 - mounting plate, 2 - parallel rod, 3 - limiting projection, 4 - insulation gap. Specific embodiments

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] The object of the present invention is to provide a multi - segment linear ion trap device and its processing technology to solve the problems existing in the prior art, reduce the processing difficulty while improving the assembly accuracy, ensure the uniformity of the axial electric potential in the ion trap transmission system, improve the ion transmission efficiency, and reduce the kinetic energy dispersion of the extracted ions.

[0035] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Embodiment 1

[0037] As shown in Figures 1 - 6 , this embodiment provides a multi - segment linear ion trap device, including a mounting bracket and a quadrupole rod group. The quadrupole rod group can be installed in the mounting bracket, and several limiting elements are provided on the inner wall of the mounting bracket. Each limiting element corresponds to each cutting position of the quadrupole rod group. After cutting the quadrupole rod group along each limiting element, a multi - segment cutting rod unit can be formed. During cutting, since the mounting bracket and the quadrupole rod group are first connected and fixed before cutting, there is no assembly error between the mounting bracket and the quadrupole rod group, which can avoid the non - concentric problem during assembly caused by traditional cutting first and then assembly, greatly improving the assembly accuracy and meeting the design of the multi - segment linear ion trap device. At the same time, when ions enter each segment of the cutting rod unit in sequence, they can collide with inert gas to reduce the energy of the ions so as to achieve the effect of cooling and focusing. An insulation gap 4 is formed between adjacent cutting rod units to keep each segment of the cutting rod unit mechanically and electrically separated. Each segment of the cutting rod unit is applied with voltage separately, or each segment of the cutting rod unit is powered by resistance - capacitance voltage division, so that different potential differences exist in different sections of the entire multi - segment linear ion trap device axially, and thus a more uniform axial potential gradient can be formed axially, improving the transmission efficiency and effectively reducing the influence of the velocity dispersion caused by the reduction of the axial kinetic energy velocity of the ions.

[0038] As a specific embodiment, as shown in Figures 1 - 2As shown, the mounting bracket is of a split design, specifically including four mounting plates 1. The four mounting plates 1 can enclose to form a cuboid with a hollow interior and two open ends, and the four mounting plates 1 respectively serve as the four side walls of the cuboid to provide a fixing platform for the quadrupole rod group. The quadrupole rod group includes four parallel rods 2, and the four parallel rods 2 are respectively fixed on each mounting plate 1. Each mounting plate 1 is independently arranged to ensure that the parallel rods 2 are fixed on the mounting plates 1 before cutting, that is, the positioning is completed. At this time, the whole formed by each mounting plate 1 and each parallel rod 2 is cut, so that the whole formed by each group of mounting plates 1 and each parallel rod 2 can be cut into multiple cutting rod units, and then the cutting rod units of different groups are assembled to enclose and form a cuboid structure, thus effectively avoiding the problem of non-concentric assembly. When assembling, it is no longer necessary to spend a long time on calibration, greatly improving the assembly efficiency. A number of limiting elements are provided on each mounting plate 1, and the limiting elements are used to position the cutting points of the whole formed by the mounting plate 1 and the parallel rod 2. The limiting elements located on the same mounting plate 1 are arranged in sequence along the length direction of the parallel rod 2 to facilitate cutting into multiple sections of cutting rod units. The positions of the limiting elements located on different mounting plates 1 correspond to ensure that the length positions of the cutting rod units cut from different parallel rods 2 correspond one by one. The lengths of all the parallel rods 2 are equal, the lengths of all the mounting plates 1 are equal, and the length of the parallel rod 2 is equal to the length of the mounting plate 1.

[0039] As a specific embodiment, the four parallel rods 2 are respectively independently arranged, or the four parallel rods 2 are fixed in pairs as a whole, or the four parallel rods 2 are all fixed as a whole. Those skilled in the art can select the setting mode of the parallel rods 2 according to actual needs. Preferably, as Figure 2 shown, in the actual application process, it is preferably that the four parallel rods 2 are independently arranged respectively, so as to facilitate close cooperation with the limiting elements on the mounting plate 1 to achieve subsequent precision cutting.

[0040] Preferably, in this embodiment, a precision cutting method is adopted, and the precision cutting method can adopt laser cutting, water cutting, plasma cutting, wire cutting, etc.

[0041] As a specific embodiment, there are at least two limiting elements on each mounting plate 1, so that at least three sections of cutting rod units can be formed after cutting. Preferably, as Figure 4 shown, there are three limiting elements on each mounting plate 1, so that four sections of cutting rod units can be formed after cutting, as Figure 5 shown. When it is necessary to cut into a larger number of cutting rod units, for example, when it is necessary to cut into six sections of cutting rod units, two more limiting elements can be added to each mounting plate 1, as Figure 6 shown.

[0042] The limiting element is a limiting protrusion 3 that protrudes from the inner wall of the mounting bracket towards the center of the mounting bracket. By setting the limiting protrusion 3, the positioning of the cutting point can be achieved. At the same time, it is convenient to limit the width of the insulation gap 4 according to the width of the limiting protrusion 3. Preferably, the width of the limiting protrusion 3 is 0.1 mm to 0.5 mm, and the width of the insulation gap 4 is also 0.1 mm to 0.5 mm.

[0043] The quadrupole rod group is welded to the inner wall of the mounting bracket. The preferred welding methods are arc welding, argon arc welding, carbon dioxide gas shielded welding, oxygen-acetylene welding, laser welding, and electro-slag pressure welding, etc.

[0044] The mounting bracket is made of insulating and non-air-releasing materials, such as ceramics, glass, and quartz, etc.

[0045] The quadrupole rod group is made of a conductive metal material, such as common metal materials with good conductivity like copper, aluminum, and alloys, etc.

[0046] In this embodiment, after welding the mounting bracket and the quadrupole rod group together and then performing precision cutting, multi-segment cutting rod units are respectively cut and formed on each mounting plate 1 of the mounting bracket, which can avoid the problem of non-concentricity during assembly, greatly improve the assembly accuracy, and meet the design of the multi-segment linear ion trap device. On this basis, by further subdividing each segment of the cutting rod unit, a more uniform axial potential gradient is generated in the entire ion trap transmission system, so as to ensure the consistency of the ion velocity during transmission, improve the transmission efficiency, and reduce the kinetic energy dispersion of the extracted ions.

[0047] Embodiment Two

[0048] This embodiment discloses a processing technology based on the multi-segment linear ion trap device in Embodiment One, including the following steps:

[0049] S1. Process and manufacture each mounting plate 1 of the mounting bracket and each parallel rod 2 of the quadrupole rod group, and set the corresponding number of limiting elements on one side of each mounting plate 1 according to the number of required cutting rod units, and fix each parallel rod 2 on the side of the mounting plate 1 where the limiting element is provided; taking the quadrupole rod group made of alloy material as an example, the four alloy material rods are rough processed, and the four alloy material rods can be processed into various structures that are independent, or combined in pairs, or integrated into one. Preferably, they are independent structures that can closely cooperate with the limiting protrusion 3 on the insulating bracket;

[0050] S2. Cut each parallel rod 2 along the position where the limiting element is located, and make each parallel rod 2 respectively form multi-segment cutting rod units arranged at intervals;

[0051] S3. Enclose a cuboid with the mounting plates 1 so that the corresponding cutting rod units are arranged in a rectangle, and form an ion channel inside the whole formed by the mounting plates 1 and the cutting rod units;

[0052] S4. The cutting rod units on each mounting plate 1 are located in the same plane, and power is supplied to each cutting rod unit to form an electric field required for ion transmission. Then, when ions pass through each section of the cutting rod units in sequence, they can collide with the inert gas to reduce the energy of the ions, so as to achieve the effect of cooling and focusing. At the same time, since the DC voltages applied in different sections are different, different potential differences exist in different sections of the entire transmission system in the axial direction, so as to ensure that a potential gradient can be formed in the axial direction, which can effectively reduce the influence of velocity dispersion caused by the reduction of the axial kinetic energy velocity of the ions. Finally, the ions are led out and released at the last section of the cutting rod unit.

[0053] Specifically, in S1, when manufacturing the mounting bracket, first manufacture the blank of the mounting plate 1. Taking ceramic materials as an example, press the ceramic blank with a corresponding mold. The ceramic materials can be selected from materials such as alumina, zirconia, and machinable ceramics. Sinter the ceramic blank into a ceramic blank, and the sintered ceramic blank needs to be finely processed by a grinding machine or a carving machine with high precision to form the shape of each insulating gap 4. The width of the insulating gap 4 should be as small as possible, but it should be ensured that conduction or discharge does not occur between adjacent two sections of the cutting units to maintain electrical separation, and the positions of the limiting protrusions 3 on each mounting plate 1 correspond to each other. The width of the limiting protrusion 3 is preferably 0.1 mm to 0.5 mm, and the machining accuracy of the limiting protrusion 3 is not less than 0.01 mm. In this embodiment, a simple flat blank plate can also be directly ground.

[0054] In the present invention, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A multi-stage linear ion trap device, characterized in that: It includes a mounting bracket and a quadrupole rod group. The quadrupole rod group can be installed inside the mounting bracket, and several limiting elements are provided on the inner wall of the mounting bracket. Each of the limiting elements corresponds to each cutting position of the quadrupole rod group. After cutting the quadrupole rod group along each of the limiting elements, multiple cut rod units can be formed, and an insulating gap is formed between adjacent cut rod units. Each section of the cut rod unit is applied with voltage separately, or each section of the cut rod unit is powered by resistance-capacitance voltage division.

2. The multi-stage linear ion trap device according to claim 1, wherein: The mounting bracket includes four mounting plates. The four mounting plates can enclose to form a cuboid with a hollow interior and two open ends. The quadrupole rod group includes four parallel rods, and the four parallel rods are respectively fixed to each of the mounting plates. Several of the limiting elements are provided on each of the mounting plates. The limiting elements located on the same mounting plate are arranged in sequence along the length direction of the parallel rod, and the positions of the limiting elements located on different mounting plates correspond to each other.

3. The multi-stage linear ion trap device according to claim 2, wherein: The four parallel rods are independently arranged, or two of the four parallel rods are fixed together as a unit, or all four parallel rods are fixed together as a unit.

4. The multi-stage linear ion trap device according to claim 2, wherein: There are at least two of the limiting elements on each of the mounting plates.

5. The multi-stage linear ion trap device according to claim 1, characterized in that: The limiting element is a limiting protrusion protruding from the inner wall of the mounting bracket towards the center of the mounting bracket.

6. The multi-stage linear ion trap device according to claim 1, characterized in that: The quadrupole rod group is welded to the inner wall of the mounting bracket.

7. The multi-stage linear ion trap device according to claim 1, wherein: The mounting bracket is made of an insulating and non-outgassing material.

8. The multi-stage linear ion trap device according to claim 1, wherein: The quadrupole rod group is made of a conductive metal material.

9. A processing technology for the multi-section linear ion trap device according to any one of claims 1-8, characterized in that: It includes the following steps: S1. Process and manufacture each mounting plate of the mounting bracket and each parallel rod of the quadrupole rod group, and set the corresponding number of limiting elements on one side of each mounting plate according to the number of required cut rod units, and fix each parallel rod to the side of the mounting plate where the limiting element is provided. S2. Cut each parallel rod along the position where the limiting element is located, and make each parallel rod form multiple cut rod units arranged at intervals. S3. Enclose the cuboid with the mounting plates so that the cut rod units with corresponding positions are arranged in a rectangle, and form an ion channel inside the whole enclosed by the mounting plates and the cut rod units. S4. The cut rod units on each mounting plate are located in the same plane, and power is applied to each cut rod unit to form an electric field required for ion transmission.

10. The processing technology of the multi-segment linear ion trap device according to claim 9, characterized in that: In S1, when manufacturing the mounting bracket, first manufacture the mounting plate blank, press the raw material blank with a mold. After the mounting plate blank is sintered and formed, initially press the limiting protrusions on the mounting plate blank, and the positions of the limiting protrusions on multiple mounting plates correspond to each other.

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