A two-dimensional ion lens with controllable ion beam and a control method thereof

Abstract

The present invention discloses a two-dimensional ion lens with controllable ion beam and a control method thereof, comprising a PCB body and a metal lattice located on the surface of the PCB body, wherein the PCB body comprises a voltage control circuit, and the voltage control circuit is used to control the voltage of the metal lattice; the extended surface of the PCB body is perpendicular to the transmission direction of the ion beam, and is provided with a through hole for penetrating the ion beam. This technical solution significantly reduces the space occupied by the ion lens device in the axial transmission direction, reduces the system volume as a whole, enhances the portability of the mass spectrometer, improves the precision of the electric field control, and broadens the application field. At the same time, the high integration of the PCB reduces the manufacturing cost and maintenance cost, improves the stability and reliability of the system, meets the requirements of energy conservation and emission reduction, and provides strong support for the miniaturization design of the mass spectrometer and the improvement of its market competitiveness.

Description

Technical Field

[0001] The present invention belongs to the technical field of mass spectrometry, and more specifically, relates to the technical field of ion lenses. Background Art

[0002] Mass spectrometers usually include an ion lens system to focus and transmit charged ions. After the charged ion beam passes through the injection cone, it quickly and diverges into the vacuum system under the influence of the huge gas pressure difference. In order to prevent ion loss, the ion lens focuses and directs the sample ions, compressing them into a compact ion beam flow, thereby ensuring ion transmission efficiency and background noise control.

[0003] For example, the Chinese patent number CN 112420481 A discloses an ion lens device, which arranges multiple electrodes in parallel in the axial transmission direction and controls the charged ion beam by changing the voltage of different electrodes. The horizontal electrode layout can produce a relatively uniform electric field distribution, and the control and simulation of the electric field are relatively simple, which is convenient for predicting and controlling the ion trajectory.

[0004] However, this type of ion lens device occupies a large space in the axial transmission direction. This spatial layout limits the miniaturization design and portability of the mass spectrometer, and is not conducive to the application and development of mass spectrometry technology in the fields of field detection and portable equipment. Therefore, how to optimize the structure of the ion lens device and reduce its space occupancy in the axial transmission direction has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes a two-dimensional ion lens with controllable ion beam and a control method thereof, which greatly reduces the overall system structure of the ion lens and ensures the miniaturization design and portability improvement of the mass spectrometer.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] A two-dimensional ion lens with controllable ion beam, characterized in that it comprises a PCB body and a metal lattice located on the surface of the PCB body, the PCB body comprises a voltage control circuit, and the voltage control circuit is used to control the voltage of the metal lattice; the extended surface of the PCB body is perpendicular to the transmission direction of the ion beam, and is provided with a through hole for penetrating the ion beam.

[0008] PCB (Printed Circuit Board) is a conductive board used to connect and support electronic components. It has a high degree of integration and can integrate complex circuits in a limited space. Therefore, the voltage control circuit can be integrated into the PCB body through existing technology, and then the metal lattice can be processed on the surface of the PCB body through etching technology. The voltage of different metal points on the metal lattice is controlled by the voltage control circuit, so as to achieve fine control of the electric field. At the same time, PCB reduces the volume of the ion lens system. The specific control principle is as follows. First, if a unit voltage is applied to a single metal on the metal lattice through the voltage control circuit, and the remaining metal points are grounded, the transmission matrix of the transmitted electric field can be obtained as follows: , thus obtaining a single metal point applied voltage The resulting field is According to the uniqueness of the electric field and the principle that the electric field can be linearly superimposed, we can write the total electric potential field for: .

[0009] It can be seen that changing the voltage on the metal lattice can completely change the electric field distribution in the ion lens system, and the more points the metal lattice has, the finer the control of the total electric potential field. Therefore, the voltage of different metal points on the metal lattice can be controlled by the voltage control circuit to reshape the asymmetric beam caused by air flow turbulence and other reasons.

[0010] The traditional horizontal electrode layout causes the ion lens system to occupy more space in the axial direction, which is not conducive to the miniaturization and portability of the mass spectrometer. Our technical solution realizes the vertical layout of the electrode sheet and the control module through innovative design and technological breakthroughs. The following are our technical considerations and implementation process:

[0011] High-density vertical lattice design: The metal lattice is processed on the surface of the PCB body by etching, and the extended surface of the PCB body is perpendicular to the transmission direction of the ion beam, thereby realizing a high-density vertical lattice design. In addition, the micro-machining process in the prior art can integrate the voltage control circuit into the PCB body, and on the basis of maintaining precise control of the voltage of each electrode point, the miniaturization of the voltage control circuit is realized and can meet the needs of vertical layout.

[0012] Three-dimensional electric field simulation and optimization: Some relatively advanced three-dimensional electric field simulation software has gradually emerged in the existing technology, such as COMSOL, CST Studio Suite, etc. We can use these calculation software to accurately calculate the contribution of each electrode point in the vertical lattice to the electric field and optimize it to ensure that each electrode point can be independently and accurately regulated in voltage even in the vertical layout.

[0013] In summary, this technical solution significantly reduces the space occupied by the ion lens device in the axial transmission direction, reduces the overall system volume, enhances the portability of the mass spectrometer, improves the precision of electric field control, and broadens the application field. At the same time, the high integration of PCB reduces manufacturing costs and maintenance costs, improves the stability and reliability of the system, meets the requirements of energy conservation and emission reduction, and provides strong support for the miniaturization design of mass spectrometers and the improvement of market competitiveness.

[0014] As a preferred embodiment of the present invention, the metal lattice is divided into a positive electrode area and a negative electrode area, the negative electrode area is an area close to the through hole, and the positive electrode area is an area far away from the through hole.

[0015] In order to effectively control the ion beam, an electric field gradient needs to be formed on its path. The setting of the positive and negative regions can produce such a gradient so that the ions are appropriately accelerated or decelerated when passing through the lens. At the same time, the voltage near the through-hole area is maintained at a negative low potential to ensure that the ion beam can pass through the lens without being hindered by high potential obstacles, and reduce the deflection of ions when passing through the lens, which helps to maintain the linearity of the ion beam.

[0016] As a preferred embodiment of the present invention, the two-dimensional ion lens with controllable ion beam flow further includes a circular ring electrode located on the surface of the PCB board body, the circular ring electrode includes an inner ring and an outer ring, and the metal lattice is arranged between the inner ring and the outer ring.

[0017] When regulating the electric field, the use of inner and outer ring electrodes can reduce the number of electrodes and the number of control steps in the edge area where high-precision control is not required, thereby simplifying the entire control process. This allows operators to adjust the ion beam more quickly, improving the operating efficiency during experiments or production. In addition, the use of the ring electrodes in the edge area reduces the number of required electrodes and reduces the complexity of the electrode layout on the PCB board. In summary, the design of the inner ring and the outer ring electrodes plays a key role in the two-dimensional ion lens. They not only provide a uniform electric field and simplify the control process, but also improve the convenience of operation and the overall performance of the system.

[0018] As a preferred embodiment of the present invention, the two-dimensional ion lens with controllable ion beam flow further includes a grounding device, and the grounding device is connected to the other side of the PCB board body.

[0019] The grounding device can be a grounding metal connected to the other side of the PCB board, which not only improves the stability, safety and electromagnetic compatibility of the system, but also protects the circuit and equipment, providing reliable technical support for high-precision ion beam control.

[0020] A method for controlling a two-dimensional ion lens with controllable ion beam flow:

[0021] Dividing the metal lattice into a plurality of equipotential field regions, wherein the equipotential field regions are regions with the same voltage value;

[0022] The shape of the equipotential field region is a proportional scaling of the cross-sectional shape of the ion beam;

[0023] The voltage value U in the equipotential field region is calculated based on the voltage control formula, and the voltage control formula is as follows:

[0024]

[0025] U is the voltage value in the equipotential field region, R is the distance between the equipotential field region and the center point of the through hole; k and b are the first custom parameter and the second custom parameter respectively.

[0026] By changing the voltage on the metal lattice, the electric field distribution in the ion lens system can be changed, thereby realizing the regulation of the ion beam. The calculation method of the voltage value on the metal lattice is as follows: the metal lattice is divided into equipotential field regions, and the shape of the equipotential field region is proportional to the cross-sectional shape of the ion beam. Based on the voltage control formula, the voltage value in the equipotential field region is accurately controlled, and more precise voltage control can be achieved, thereby accurately controlling the distribution of the ion beam and improving the accuracy of the ion beam during the processing. The first custom parameter k and the second custom parameter b in the voltage control formula can be set by the technicians according to experience, actual use scenarios or pre-simulation. R can be the distance from the center point of the equipotential field region to the center point of the through hole, or it can be the nearest or farthest distance from the center point of the through hole in the equipotential field region. In addition, the voltage control formula provides a clear method for voltage control in the equipotential field region, simplifies the control process, and is easy to operate and maintain. In summary, this method has significant advantages in improving the control accuracy of ion beam flow, optimizing the processing process, and improving system stability, which helps to improve the overall level of related industries.

[0027] As preferred by the inventors, the method for determining the distance R is specifically as follows:

[0028] The shortest distance between the center point of the through hole and the equipotential field region is determined as the corresponding distance R.

[0029] By using the shortest distance between the center point of the through hole and the equipotential field region as R, the calculation process of the voltage control formula can be simplified, because there is no need to consider complex geometric paths or curve paths, reducing the calculation errors or measurement errors that may occur when determining the R value. In addition, since the R value is determined based on the shortest path, the voltage control can more accurately reflect the actual movement path of the ions in the lens, thereby improving the control accuracy.

[0030] As a preferred embodiment of the present invention, the control method further comprises a simulation step:

[0031] Simulating the transmission path of the ion beam based on different variable parameters respectively, and outputting the transmission path result, wherein the variable parameters include the first custom parameter k and the second custom parameter b;

[0032] The effective variable parameters are determined based on the transmission path results.

[0033] Some relatively advanced three-dimensional electric field simulation software, such as COMSOL and CST StudioSuite, are gradually emerging in the prior art. Through these software, simulations are performed, and different variable parameters (such as the first custom parameter k and the second custom parameter b) are tested to predict the transmission path of the ion beam, so as to find the optimal parameter combination and verify the feasibility of the control method before actual application, thereby reducing the trial and error cost and time in the experimental stage and improving the efficiency and effect of ion beam control.

[0034] As a preferred embodiment of the present invention, the second customized parameter b<0.

[0035] The second custom parameter b<0 makes the voltage near the through hole maintained at a negative low potential to ensure that the ion beam can pass through the lens without being hindered by high potential obstacles, and reduces the deflection of ions when passing through the lens, which helps to maintain the linearity of the ion beam.

[0036] A mass spectrometer, characterized in that it also comprises a two-dimensional ion lens with controllable ion beam flow.

[0037] As a preferred embodiment of the present invention, the mass spectrometer further comprises an ion source, a sampling cone and a transmission rod which are connected in sequence; an exit slit is provided at the other end of the transmission rod, and the ion beam flows into the two-dimensional ion lens after exiting the exit slit.

[0038] A high voltage capillary is used as the ion source, and the ions are guided to the two-dimensional ion lens through the sampling cone and the transmission rod. This not only improves the ion transmission efficiency and beam quality, but also enhances the stability of the system, providing high-precision and reliable technical support for applications such as mass spectrometry. In addition, the shape and size of the ion beam can be controlled through the precise design of the exit slit, which is crucial to improving the accuracy of mass spectrometry or other analytical techniques.

[0039] In summary, the present invention has the following beneficial effects:

[0040] 1. The space occupied by the ion lens device in the axial transmission direction is significantly reduced, the overall system volume is reduced, the portability of the mass spectrometer is enhanced, the precision of the electric field control is improved, and the application field is broadened.

[0041] 2. Keeping the voltage near the through-hole area at a negative low potential ensures that the ion beam can pass through the lens without being hindered by high potential obstacles, and reduces the deflection of ions when passing through the lens, which helps to maintain the linearity of the ion beam.

[0042] 3. The design of the inner ring and the outer ring electrodes plays a key role in the two-dimensional ion lens. They not only provide a uniform electric field and simplify the control process, but also improve the convenience of operation and the overall performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 It is a schematic diagram of the partial structure of the mass spectrometer;

[0045] Figure 2 Design end-face diagrams for two-dimensional ion lens lattice distribution;

[0046] Figure 3 It is a flow chart of the control method;

[0047] Figure 4 Schematic diagram of voltage distribution in Embodiment 1;

[0048] Figure 5 This is a simulation result diagram of Example 1;

[0049] Figure 6 This is a schematic diagram of voltage distribution in Embodiment 2;

[0050] Figure 7 It is the simulation result diagram of Example 2;

[0051] Figure 8 Cross-sectional view before and after ion beam shaping.

[0052] In the figure, 1. ion source, 2. sampling cone, 3. transmission rod, 4. exit slit, 5. metal lattice, 6. PCB board, 7. grounding device, 8. ring electrode, 81. inner ring, 82. outer ring, 9. through hole. DETAILED DESCRIPTION

[0053] The present invention is further described below by specific examples and drawings. The examples of the present invention are intended to enable those skilled in the art to better understand the present invention, and do not limit the present invention in any way.

[0054] like Figure 1 As shown, a mass spectrometer comprises an ion source 1, a sampling cone 2, a transmission rod 3, an exit slit 4 and a two-dimensional ion lens connected in sequence. The ion source 1 can use a high-voltage capillary, and guide the ions to the two-dimensional ion lens through the sampling cone 2 and the transmission rod 3. Not only the transmission efficiency and beam quality of the ions are improved, but also the stability of the system is enhanced, providing high-precision and reliable technical support for applications such as mass spectrometry. An exit slit 4 is provided at the other end of the transmission rod 3, and the ion beam enters the two-dimensional ion lens after exiting the exit slit 4. In addition, the shape and size of the ion beam can be controlled by the precise design of the exit slit 4, which is crucial to improving the accuracy of mass spectrometry or other analytical techniques.

[0055] The two-dimensional ion lens is a two-dimensional ion lens with controllable ion beam, which comprises a PCB body 6 and a metal lattice 5 located on the surface of the PCB body 6, wherein the PCB body 6 comprises a voltage control circuit, and the voltage control circuit is used to control the voltage of the metal lattice 5. The extended surface of the PCB body 6 is perpendicular to the transmission direction of the ion beam, and is provided with a through hole 9 for passing the ion beam. The other side of the PCB body 6 is connected to a grounding device 7, and the grounding device 7 can be a grounding metal. The other side of the PCB body 6 is connected to the grounding metal, which not only improves the stability, safety and electromagnetic compatibility of the system, but also protects the circuit and equipment, and provides reliable technical support for high-precision ion beam control.

[0056] PCB (Printed Circuit Board) is a conductive board used to connect and support electronic components. It has a high degree of integration and can integrate complex circuits in a limited space. Therefore, the voltage control circuit can be integrated into the PCB body 6 through existing technology, and then the metal dot matrix 5 can be processed on the surface of the PCB body 6 through etching technology. The voltage control circuit controls the voltage of different metal points on the metal dot matrix 5, thereby realizing fine control of the electric field. At the same time, PCB reduces the volume of the ion lens system.

[0057] The specific control principle is as follows: first, if a unit voltage is applied to a single metal on the metal dot matrix 5 through a voltage control circuit, and the other metal points are grounded, the transmission matrix of the transmission electric field can be obtained as follows: , thus obtaining a single metal point applied voltage The resulting field is According to the uniqueness of the electric field and the principle that the electric field can be linearly superimposed, we can write the total electric potential field for: .

[0058] It can be seen that changing the voltage on the metal lattice 5 can completely change the electric field distribution in the ion lens system, and the more points the metal lattice 5 has, the finer the control of the total electric potential field. Therefore, the voltage of different metal points on the metal lattice 5 can be controlled by the voltage control circuit to reshape the asymmetric beam caused by air flow turbulence and other reasons.

[0059] In order to effectively control the ion beam, an electric field gradient needs to be formed on its path, so the metal lattice 5 is divided into a positive region and a negative region, the negative region is the region close to the through hole 9, and the positive region is the region far away from the through hole 9. Figure 2 As shown, a circular ring electrode 8 is further provided on the surface of the PCB body 6 . The circular ring electrode 8 includes an inner circular ring 81 and an outer circular ring 82 . The metal dot matrix 5 is arranged between the inner circular ring 81 and the outer circular ring 82 .

[0060] The arrangement of the positive and negative regions can produce such a gradient that the ions are appropriately accelerated or decelerated when passing through the lens. At the same time, the voltage of the inner ring 81 is maintained at a negative low potential to ensure that the ion beam can pass through the lens without being hindered by high potential obstacles, and reduces the deflection of ions when passing through the lens, which helps to maintain the linearity of the ion beam. When regulating the electric field, the use of the inner and outer ring 82 electrodes 8 can reduce the number of electrodes and the control steps in the edge area where high-precision control is not required, thereby simplifying the entire control process. The operator can adjust the ion beam more quickly, improving the operating efficiency in the experiment or production process. In addition, the use of the ring electrode 8 in the edge area reduces the number of required electrodes and reduces the complexity of the electrode layout on the PCB board 6. In summary, the design of the inner ring 81 and the outer ring 82 electrodes 8 plays a key role in the two-dimensional ion lens. They not only provide a uniform electric field, simplify the control process, but also improve the convenience of operation and the overall performance of the system.

[0061] like Figure 3 As shown, the control method based on the two-dimensional ion lens with controllable ion beam flow is as follows:

[0062] Divide the metal lattice 5 into a plurality of equipotential field regions, where the equipotential field regions are regions with the same voltage value;

[0063] The shape of the equipotential field region is a proportional scaling of the cross-sectional shape of the ion beam;

[0064] The voltage value U in the equipotential field area is calculated based on the voltage control formula. The voltage control formula is as follows:

[0065]

[0066] U is the voltage value in the equipotential field region, R is the distance between the equipotential field region and the center point of the through hole 9; k and b are the first custom parameter and the second custom parameter respectively.

[0067] By changing the voltage on the metal lattice 5, the electric field distribution in the ion lens system can be changed, thereby realizing the regulation of the ion beam. The calculation method of the voltage value on the metal lattice 5 is as follows: the metal lattice 5 is divided into equipotential field regions, and the shape of the equipotential field region is proportional to the cross-sectional shape of the ion beam. Based on the voltage control formula, the voltage value in the equipotential field region is accurately controlled, and more precise voltage control can be achieved, thereby accurately controlling the distribution of the ion beam and improving the accuracy of the ion beam during the processing. In the voltage control formula, the method for determining the distance R is specifically: the closest distance from the center point of the through hole 9 to the equipotential field region is determined as the corresponding distance R. By using the closest distance from the center point of the through hole 9 to the equipotential field region as R, the calculation process of the voltage control formula can be simplified, because there is no need to consider complex geometric paths or curved paths, reducing the calculation errors or measurement errors that may occur when determining the R value. In addition, since the R value is determined based on the shortest path, the voltage control can more accurately reflect the actual movement path of the ions in the lens, thereby improving the control accuracy.

[0068] The first custom parameter k and the second custom parameter b can be set by the technician according to experience, actual usage scenarios or pre-simulation. Among them, the specific method of determining the first custom parameter k and the second custom parameter b by pre-simulation is as follows: some relatively advanced three-dimensional electric field simulation software, such as COMSOL and CSTStudio Suite, have gradually appeared in the prior art. These softwares simulate the transmission path of the ion beam based on different variable parameters and output the transmission path results. The variable parameters include the first custom parameter k and the second custom parameter b. Determine the optimal first custom parameter k and the second custom parameter b based on the transmission path results. This method predicts the transmission path of the ion beam by testing different variable parameters (such as the first custom parameter k and the second custom parameter b), thereby finding the optimal parameter combination, and verifying the feasibility of the control method before actual application, reducing the trial and error cost and time in the experimental stage, and improving the efficiency and effect of ion beam control.

[0069] Among them, before performing variable parameter simulation, the technician can pre-set the second custom parameter b<0, so that the voltage near the through hole 9 is maintained at a negative low potential to ensure that the ion beam can pass through the lens without being hindered by high potential obstacles, and reduce the deflection of ions when passing through the lens, which helps to maintain the linearity of the ion beam.

[0070] Embodiment 1

[0071] Based on the above control method, a beam of ion beam is focused, and the voltage value distribution on the annular electrode 8 and the metal lattice 5 is as follows: Figure 4As shown. The solid black area is the voltage value corresponding to the upper left corner. It can be seen that in this embodiment, the voltage value of the inner ring 81 is -9v, the voltage value of the outer ring 82 is 54v, and the voltage values ​​of the metal lattice 5 are respectively set to -6v, -1v, 6v, 15v, 26v, and 39v from the inside to the outside. And the shape of the boundary of each equipotential field region is approximately a circle, which is proportional to the cross-sectional shape of the ion beam. Figure 6 As shown, by predicting the transmission path of the ion beam through the simulation software, it can be seen that based on the above-mentioned voltage control distribution method, the focusing control of the ion beam can be better achieved.

[0072] Embodiment 2

[0073] In addition to focusing the ion beam, the present technical solution can also shape the beam by changing the voltage distribution of the metal lattice 5. Figure 6 As shown in the figure, the solid black area is the voltage value corresponding to the upper left corner. By setting the voltage values ​​at different locations, the voltage of an ion beam with an elliptical cross section can be controlled. Figure 7 , 8 As shown, by predicting the transmission path of the ion beam through simulation software, it can be seen that based on the above-mentioned voltage control distribution method, the cross-section of the ion beam is shaped from an ellipse to a circle while achieving focusing.

[0074] It should be noted that the above embodiments are only detailed descriptions of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, there will be changes in the specific implementation methods based on the ideas provided by the present invention, and these changes are also considered to be within the scope of protection of the present invention.

Claims

1. A two-dimensional ion lens with controllable ion beam flow, characterized in that: The invention comprises a PCB body (6) and a metal lattice (5) located on the surface of the PCB body (6), wherein the PCB body (6) comprises a voltage control circuit, and the voltage control circuit is used to control the voltage of the metal lattice (5); the extension surface of the PCB body (6) is perpendicular to the transmission direction of the ion beam, and is provided with a through hole (9) for penetrating the ion beam, and further comprises a circular ring electrode (8) located on the surface of the PCB body (6), wherein the circular ring electrode (8) comprises an inner circular ring (81) and an outer circular ring (82), and the metal lattice (5) is arranged between the inner circular ring (81) and the outer circular ring (82).

2. A two-dimensional ion lens with controllable ion beam flow according to claim 1, characterized in that: The metal lattice (5) is divided into a positive electrode region and a negative electrode region, the negative electrode region is a region close to the through hole (9), and the positive electrode region is a region far from the through hole (9).

3. The two-dimensional ion lens with controllable ion beam flow according to claim 1, characterized in that: The two-dimensional ion lens with controllable ion beam flow further comprises a grounding device (7), and the grounding device (7) is connected to the other side of the PCB body (6).

4. A control method for adjusting a two-dimensional ion lens with controllable ion beam current as claimed in claim 1, characterized in that: The following steps are included: Dividing the metal lattice (5) into a plurality of equipotential field regions, wherein the voltage value in each of the equipotential field regions is the same; The shape of the boundary line of the equipotential field region is a proportional scaling of the cross-sectional shape of the ion beam; The voltage value U in each equipotential field region is calculated based on the voltage control formula, and the voltage control formula is specifically as follows: U is the voltage value in the equipotential field region, R is the distance between the equipotential field region and the center point of the through hole (9); k and b are the first custom parameter and the second custom parameter, respectively.

5. A control method according to claim 4, characterized in that: The method for determining the distance R is specifically as follows: The shortest distance between the center point of the through hole (9) and the equipotential field region is determined as the corresponding distance R.

6. A control method according to claim 4, characterized in that: The control method further comprises a simulation step: Simulating the transmission path of the ion beam based on different variable parameters respectively, and outputting the transmission path result, wherein the variable parameters include the first custom parameter k and the second custom parameter b; Optimal variable parameters are determined based on the transmission path results.

7. A control method according to claim 6, characterized in that: The second custom parameter b<0.

8. A mass spectrometer, characterized in that A two-dimensional ion lens with controllable ion beam current as described in any one of claims 1 to 3.

9. A mass spectrometer according to claim 8, characterized in that: The mass spectrometer also comprises an ion source (1), a sampling cone (2) and a transmission rod (3) which are connected in sequence; an exit slit (4) is provided at the other end of the transmission rod (3); and the ion beam flows out of the exit slit (4) and enters a two-dimensional ion lens in which the ion beam flow is controllable.

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