A method for positioning a Faraday cup for a hydrogen isotope accelerator mass spectrometer

Abstract

The application provides a positioning method for Faraday cups of a hydrogen isotope accelerator mass spectrometer, comprising the following steps: S1, simulating the motion trajectories of nine ion beams of sample ions to determine the theoretical positions of each Faraday cup; S2, determining the installation position of a first Faraday cup; S3, adjusting the magnetic field current I0 to maximize the ion beam intensity entering the first Faraday cup, and determining the adjusted magnetic field current as the sample magnetic field current I1; S4, according to the theoretical position of an Nth Faraday cup, setting a first fluorescent screen and a second fluorescent screen one by one in a one-to-one correspondence at a first position and a second position respectively, and collecting the first light spot coordinates and the second light spot coordinates corresponding to the Nth Faraday cup under the condition of the sample magnetic field current I1; and S5, based on step S2, determining the position of the Nth Faraday cup according to the first light spot coordinates and the second light spot coordinates. The embodiment can ensure high convergence of received ion beams and large ion beam intensity, and further make the measurement more accurate.

Description

Technical Field

[0001] This invention relates to the field of isotope analysis technology, and in particular to a method for locating a Faraday cup in a hydrogen isotope accelerator mass spectrometer. Background Technology

[0002] A Faraday cup is a vacuum detector made of metal in a cup shape, used to measure the intensity of incident charged particles. It is suitable for long-term measurements under high heat loads, and the measured current can be used to determine the number of incident electrons or ions. It features convenient and quick installation and maintenance, and a long service life.

[0003] When measuring the abundance of hydrogen isotopes, traditional mass spectrometers typically use multiple Faraday cups to measure ions with different mass-to-charge ratios. However, inaccurate positioning of the Faraday cups can severely affect the measurement of each ion, thus impacting the accuracy of hydrogen isotope abundance measurements. Summary of the Invention

[0004] The summary section of this invention provides a brief overview of the concepts, which will be described in detail in the detailed description section that follows. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0005] Some embodiments of the present invention provide a method for locating a Faraday cup in a hydrogen isotope accelerator mass spectrometer to solve the technical problems mentioned in the background section above.

[0006] This method describes a positioning method for Faraday cups in a hydrogen isotope accelerator mass spectrometer. The hydrogen isotope accelerator mass spectrometer includes a sample introduction assembly, an ECR ion source, an accelerating tube, a magnetic mass analyzer, and nine spaced-apart Faraday cups. The ECR ion source ionizes a mixed gas entering through the sample introduction assembly, generating nine ion beams with different mass-to-charge ratios. The accelerating tube is connected to the ECR ion source. Under the action of the extraction voltage of the ECR ion source and the accelerating voltage of the accelerating tube, the nine accelerated ion beams with different mass-to-charge ratios enter the magnetic analyzer connected to the accelerating tube. The magnetic analyzer separates the ion beams with different mass-to-charge ratios in the mixed ion beam and directs them into their corresponding Faraday cups. The positioning method includes: S1, based on beam simulation software, setting the magnetic field current I0 and adjusting the accelerating tube voltage U0 to simulate nine different ion types in the sample ions. S1. Determine the coordinates of two corner points of the theoretical position of each Faraday cup based on the trajectory of the beam movement; S2. Determine the installation position of the first Faraday cup based on the corner point coordinates of the first Faraday cup and the convergence degree of the ion beam of the sample ions; S3. Maximize the intensity of the ion beam current entering the first Faraday cup by adjusting the magnetic field current I0, and determine the adjusted magnetic field current as the sample magnetic field current I1; S4. Based on the theoretical position of the Nth Faraday cup, set the first fluorescent screen and the second fluorescent screen in a one-to-one correspondence between the first position and the second position, respectively. Under the condition of the sample magnetic field current I1, collect the first spot coordinates and the second spot coordinates of the ion beam corresponding to the Nth Faraday cup converging on the first fluorescent screen and the second fluorescent screen; S5. Based on step S2, determine the position of the Nth Faraday cup based on the first spot coordinates and the second spot coordinates.

[0007] Optionally, the coordinates of the two corner points include the coordinates of the center point of the bottom of the Faraday cup and the center point of the rim of the cup.

[0008] Optionally, step S2 includes: connecting the two corner points to construct a reference line; aligning the axis of the first Faraday cup with the reference line; sliding the first Faraday cup along the reference line, and determining the installation position of the first Faraday cup as the ion beam converged by the first Faraday cup has the highest convergence.

[0009] Optionally, step S3 includes: generating a sample ion beam by ionizing the sample gas through the ECR ion source; adjusting the magnetic field current under the condition of the accelerating tube voltage U0 to determine the sample ion beam current intensity in the first Faraday cup; and determining the adjusted magnetic field current as the sample magnetic field current I1 in response to the sample ion beam current intensity reaching its peak value.

[0010] Optionally, step S4 includes: a first camera is disposed facing the first fluorescent screen; and a second camera is disposed facing the second fluorescent screen.

[0011] Optionally, step S4 further includes: installing a first fluorescent screen at the theoretical position of the Nth Faraday cup as the first position; adjusting the accelerating tube voltage U0 under the condition of sample magnetic field current I1 so that the motion trajectory of the sample ion beam is the same as that of the Nth ion beam; acquiring an image of the first spot where the sample ion beam converges on the first fluorescent screen using a first camera, and determining the coordinates of the first spot based on the image.

[0012] Optionally, step S4 includes: installing a second fluorescent screen in a preset direction at the theoretical position of the Nth Faraday cup; adjusting the accelerating tube voltage U0 under the condition of sample magnetic field current I1 so that the motion trajectory of the sample ion beam is the same as that of the Nth ion beam; acquiring an image of the second spot where the sample ion beam converges on the second fluorescent screen using a second camera, and determining the coordinates of the second spot based on the image.

[0013] Optionally, the step of acquiring an image of the first spot where the sample ion beam converges on the first fluorescent screen using a first camera, and determining the coordinates of the first spot based on the image, includes: under dark field conditions, acquiring a first dark field image of the first spot converging on the first fluorescent screen using the first camera; under bright field conditions, acquiring a first bright field image of the first spot converging on the first fluorescent screen using the first camera; comparing the first dark field image with the first bright field image, and determining the coordinates of the first spot based on the scribed lines on the first fluorescent screen.

[0014] Optionally, the step of acquiring an image of the second spot where the sample ion beam converges on the second fluorescent screen using a second camera, and determining the coordinates of the second spot based on the image, includes: under dark field conditions, acquiring a second dark field image of the second spot converging on the second fluorescent screen using the second camera; under bright field conditions, acquiring a second bright field image of the second spot converging on the second fluorescent screen using the second camera; comparing the second dark field image with the second bright field image, and determining the coordinates of the second spot based on the scribe lines on the second fluorescent screen.

[0015] Optionally, step S5 includes: constructing a reference line by connecting the coordinates of the first spot and the coordinates of the second spot; aligning the axis of the Nth Faraday cup with the reference line; sliding the Nth Faraday cup along the reference line, and determining the installation position of the Nth Faraday cup as the ion beam with the highest concentration in response to the Nth Faraday cup.

[0016] The above embodiments of the present invention have the following beneficial effects: the positioning method of Faraday cups for hydrogen isotope accelerator mass spectrometers according to the present invention can improve the positioning accuracy of each Faraday cup.

[0017] Specifically, the coordinates of the two corner points of the theoretical position of each Faraday cup are first determined. Then, based on these theoretical positions, the position of the first Faraday cup is continuously refined according to the concentration of the ion beam, adjusting the position to achieve a higher concentration of ions entering the first Faraday cup, thereby improving the accuracy of the ion measurement. Next, the sample magnetic field current I1 is determined to maximize the ion beam current intensity entering the first Faraday cup, which also improves the accuracy of the ion measurement. Finally, the position of the Faraday cup is determined by using the first and second fluorescent screens to determine the coordinates of the first and second spot points corresponding to the ion convergence.

[0018] This ensures that the Faraday cups receive a high concentration of ion beams and a high intensity of ion beams after positioning, thereby making the measurement of ions more accurate and the position of each Faraday cup more precise. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of a hydrogen isotope accelerator mass spectrometer according to the present invention.

[0021] Figure 2 This is a flowchart of some embodiments of a Faraday cup positioning method for a hydrogen isotope accelerator mass spectrometer according to the present disclosure.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1: Sample gas pipeline; 2: Auxiliary support gas pipeline; 3: Gas inlet system; 4: ECR ion source; 5: Accelerator tube; 6: Mass analyzer; 7: Faraday cup. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of an embodiment of a hydrogen isotope accelerator mass spectrometer according to the present invention. Figure 1 As shown, the hydrogen isotope accelerator mass spectrometer includes a sample introduction assembly, an ECR ion source 4, an acceleration tube 5, a magnetic analyzer 6, and nine Faraday cups.

[0029] The sample introduction assembly is connected to the ECR ion source 4. Specifically, the sample introduction assembly includes an inlet gas system 3, a sample gas conduit 1, and an auxiliary support gas conduit 2. The sample gas conduit 1 is connected to the left inlet end of the inlet gas system 3. Figure 1 The auxiliary support gas pipe 2 is connected to the left intake end of the intake system 3 (in the direction of the middle) to introduce hydrogen isotope gas into the aforementioned intake system 3. Figure 1 The connection (in the direction of the middle) is used to introduce auxiliary gas into the aforementioned intake system 3. The right side of the aforementioned intake system 3 ( Figure 1 The outlet end (in the direction of the middle) is connected to the above-mentioned ECR ion source 4.

[0030] Because the auxiliary gas introduced into the aforementioned auxiliary support gas pipe 2 serves as a support, it further enables the ECR ion source 4 to generate H2 after acting on the mixed gas. + H2 + / D + T + / HD + / 3 He + / H3 + D2 + DT + T2 + C + N + and O + Monoatomic ions. As an example, the aforementioned auxiliary gas could be argon, which can effectively reduce H2. + The generation of H2 is beneficial to the breakdown of H2 and promotes the production of H2. + The generation of [the gas]. As another example, the aforementioned auxiliary gas could also be helium.

[0031] The aforementioned accelerating tube 5 is connected to the outlet end of the ECR ion source 4. The accelerating tube 5 can be an electric field accelerator. Its two ends are connected to a high voltage source and ground, respectively. In this way, the mixed ion beam is accelerated under the influence of a high-voltage electrostatic field as it passes through the accelerating tube 5, thus obtaining higher energy.

[0032] In summary, the energy of the mixed ion beam is achieved through pre-acceleration by the extraction voltage of the ECR ion source 4 and acceleration by the high-voltage electrostatic field of the acceleration tube 5.

[0033] The aforementioned magnetic analyzer includes an electromagnet with an electromagnetic field strength continuously adjustable between 0 and 1 T. Based on the different deflection radii of ion beams with different mass-to-charge ratios in a magnetic field, this magnetic analyzer can separate H from the aforementioned mixed ion beam. + H2 + / D + T + / HD + / 3 He + / H3 + D2 + DT + T2 + C + N + and O + Nine ion beams are separated to form the first to ninth ion beams. These beams are then injected into nine Faraday cups 7 spaced apart.

[0034] The Faraday cup 7 can determine the ion signal intensity of the corresponding ion beam, and thus determine the number of incident ions.

[0035] Please refer to the following. Figure 2 , Figure 2 This describes a method for locating a Faraday cup in a hydrogen isotope accelerator mass spectrometer. For example... Figure 2 As shown, the positioning method includes the following steps:

[0036] Step S1: Based on beam simulation software, by setting the magnetic field current I0 and adjusting the accelerating tube voltage U0, the sample ions simulate the motion trajectory of nine ion beams, and determine the coordinates of the two corner points of the theoretical position of each Faraday cup.

[0037] In some embodiments, an ion is selected as the sample ion. By inputting the initial magnetic field current I0 and the initial accelerating tube voltage U0 into the relevant beam simulation software, the trajectory of the sample ion beam can be simulated. Next, by changing the accelerating tube voltage U0, the trajectory of the sample ion beam can be changed, thereby simulating the trajectories of nine ion beams under accelerating tube voltage U0 and magnetic current I0.

[0038] Furthermore, the location where the ion beam converges most concentrated is determined as the theoretical position of the corresponding Faraday cup. Then, the coordinates of two corner points of each Faraday cup's theoretical position are determined. Specifically, these corner point coordinates can be the coordinates of the center point of the cup's bottom and the center point of its rim within the target chamber.

[0039] Step S2: Determine the installation position of the first Faraday cup based on the corner coordinates of the first Faraday cup and the convergence degree of the ion beam of the sample ions.

[0040] In some embodiments, when installing the first Faraday cup, the coordinates of the two corner points of the first Faraday cup can be aligned with the coordinates of the two corner points of the theoretical position of the first Faraday cup. Then, the position with the highest ion beam concentration can be found, and the first Faraday cup can be finely adjusted to face that position to finally determine the installation position of the first Faraday cup.

[0041] In some optional implementations, a reference line is first constructed by connecting the coordinates of the two corner points of the theoretical position of the first Faraday cup. Next, the axis of the first Faraday cup is aligned with this reference line, and the cup is slid along the reference line. When the concentration of the ion beam gathered by the first Faraday cup is at its highest, the movement is stopped, and this position is determined as the installation position of the first Faraday cup. At this point, the first Faraday cup not only receives the densest ion beam, but its installation angle also matches the incident angle of the ion beam, thereby improving the accuracy of measuring the ion beam entering the first Faraday cup.

[0042] Step S3: By adjusting the magnetic field current I0, the intensity of the ion beam entering the first Faraday cup is maximized, and the adjusted magnetic field current is determined as the sample magnetic field current I1.

[0043] In some embodiments, the ion beam intensity entering the first Faraday cup is maximized, which improves the accuracy of the ion measurement. Therefore, the magnetic field current is adjusted under the condition of the accelerating tube voltage U0.

[0044] Specifically, the sample gas is first ionized using an ECR ion source to generate a sample ion beam. For example, helium gas is introduced through the aforementioned sample introduction assembly, and ionized by the ECR ion source to form... 4 He + An accelerating tube voltage U0 and a magnetic field current I0 are applied, accelerating the sample ions. After being deflected by a magnetic mass analyzer, the ions are injected into the first Faraday cup installed in the target chamber. Finally, keeping the accelerating tube voltage U0 constant, the magnetic field current I1 is changed. The sample ion beam intensity in the first Faraday cup is determined. In response to the sample ion beam intensity reaching its peak, at which point the magnetic field intensity is optimal, the adjusted magnetic field current is determined as the sample magnetic field current I1.

[0045] Step S4: Based on the theoretical position of the Nth Faraday cup, set up a first fluorescent screen and a second fluorescent screen in a one-to-one correspondence between the first position and the second position. Under the condition of sample magnetic field current I1, collect the coordinates of the first spot and the second spot corresponding to the Nth Faraday cup, which converge on the first and second fluorescent screens.

[0046] In some embodiments, the Nth Faraday cup represents the second through ninth Faraday cups. The following description uses the positioning process of the second Faraday cup as an example.

[0047] The aforementioned first position can be the theoretical position of the second Faraday cup as determined above. A first fluorescent screen is set at this first position, and a first camera is set at the observation port of the target chamber facing the first fluorescent screen. The parameters of the first camera are set to enable it to clearly acquire the image of the first fluorescent screen.

[0048] Next, the magnetic field strength is determined using the sample magnetic field current I1, and the accelerating tube voltage is adjusted so that the sample ions move in the same trajectory as the second ion beam. When the sample ion beam passes through the first fluorescent screen, it converges into a small and bright first spot on the screen.

[0049] An image can be captured on a first fluorescent screen using a first camera. The image is then processed by adjusting brightness, contrast, and color balance. Finally, an image processing algorithm is used to identify the features of the first light spot and locate its coordinates.

[0050] In some optional implementations of the embodiments, the first dark field image and the first bright field image can be acquired by the first camera when the sample ion beam passes through the first fluorescent screen and generates the first light spot, respectively, under dark field conditions and bright field conditions. The pixel coordinate position of the first light spot is determined by the first dark field image, and the corresponding scribe line position on the first fluorescent screen is found by the first bright field image, thereby determining the coordinates of the first light spot.

[0051] In some embodiments, the second position may be adjacent to the first position, or it may be determined by the theoretical position of the second Faraday cup along a preset direction. The preset direction may be the arrangement direction of multiple Faraday cups. Those skilled in the art can adjust this according to the actual situation.

[0052] A second fluorescent screen is set at this second position, and a second camera is set at the observation port of the target chamber facing the second fluorescent screen. The parameters of the second camera are set to clearly capture the image of the second fluorescent screen.

[0053] Next, the magnetic field strength is determined using the sample magnetic field current I1, and the accelerating tube voltage is adjusted so that the sample ions move in the same direction as the second ion beam. When the sample ion beam passes through the second fluorescent screen, it converges into a small and bright second spot on the screen.

[0054] The image on the second fluorescent screen can be captured by the second camera. Then, the brightness, contrast and color balance of the image are adjusted. Finally, the features of the second light spot are identified and the coordinates of the second light spot are located by the image processing algorithm.

[0055] It should be noted that a first fluorescent screen and a first camera can be set up first. After determining the coordinates of the first light spot, the first fluorescent screen can be moved to a second position to serve as the second fluorescent screen. Similarly, the first camera can be moved to the opposite side of the second fluorescent sample to serve as the second camera.

[0056] In some optional implementations of the embodiments, a second dark-field image and a second bright-field image can be acquired by a second camera when the sample ion beam passes through the second fluorescent screen to generate a second light spot, under dark-field and bright-field conditions, respectively. The pixel coordinates of the second light spot are determined by the second dark-field image, and the corresponding scribe line position on the second fluorescent screen is found by the second bright-field image, thereby determining the coordinates of the second light spot.

[0057] Step S5: Based on step S2, determine the position of the Nth Faraday cup according to the coordinates of the first light spot and the coordinates of the second light spot.

[0058] In some embodiments, the first and second spot coordinates can be used as the coordinates of two corner points in step S2. Specifically, a reference line is constructed by connecting the first and second spot coordinates; the axis of the second Faraday cup is aligned with the reference line; and the second Faraday cup is slid along the reference line. The installation position of the second Faraday cup is determined in response to the highest concentration of the ion beam gathered by the second Faraday cup.

[0059] The present invention discloses a method for positioning a Faraday cup in a hydrogen isotope accelerator mass spectrometer. In steps S2 and S5, a reference line is constructed using the coordinates of two corner points, so that the installation angle of the Faraday cup matches the incident angle of the ion beam, thereby improving the accuracy of ion beam measurement entering the first Faraday cup.

[0060] Furthermore, by simulating the trajectory of the corresponding ion beam using sample ions and collecting the coordinates of the first and second spot on the first and second fluorescent screens, the motion of the ion beam can be more realistically reflected. Therefore, using these coordinates as the corner coordinates of the Faraday cup is more accurate, thus making the positioning of the Faraday cup more accurate.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for positioning a Faraday cup in a hydrogen isotope accelerator mass spectrometer, characterized in that, The hydrogen isotope accelerator mass spectrometer includes a sample introduction assembly, an ECR ion source, an acceleration tube, a magnetic mass analyzer, and nine spaced-apart Faraday cups. The ECR ion source is used to ionize the mixed gas entering through the sample introduction assembly to generate nine ion beams with different mass-to-charge ratios. The accelerating tube is connected to the ECR ion source. Under the action of the extraction voltage of the ECR ion source and the accelerating voltage of the accelerating tube, the nine ion beams with different mass-to-charge ratios that are accelerated enter the magnetic analyzer connected to the accelerating tube. The magnetic analyzer separates ion beams with different mass-to-charge ratios in the mixed ion beam and directs them into the corresponding Faraday cups. The positioning method includes: S1. Based on beam simulation software, by setting the magnetic field current I0 and adjusting the accelerating tube voltage U0, the sample ions simulate the motion trajectory of nine ion beams, and determine the coordinates of the two corner points of the theoretical position of each Faraday cup. S2. Determine the installation position of the first Faraday cup based on the corner coordinates of the first Faraday cup and the convergence of the ion beam of the sample ions; S3. By adjusting the magnetic field current I0, the intensity of the ion beam entering the first Faraday cup is maximized, and the adjusted magnetic field current is determined as the sample magnetic field current I1. S4. Based on the theoretical position of the Nth Faraday cup, a first fluorescent screen and a second fluorescent screen are respectively set up at the first position and the second position in a one-to-one correspondence. Under the condition of sample magnetic field current I1, the coordinates of the first spot and the second spot corresponding to the Nth Faraday cup are collected at the convergence of the ion beam on the first fluorescent screen and the second fluorescent screen. The theoretical position of the Nth Faraday cup is used as the first position, and the second position is determined by the theoretical position of the second Faraday cup along a preset direction. The preset direction is the arrangement direction of the multiple Faraday cups. S5. Based on steps S2 and S4, determine the position of the Nth Faraday cup according to the coordinates of the first light spot and the coordinates of the second light spot.

2. The positioning method according to claim 1, characterized in that, The coordinates of the two corner points include the coordinates of the center point of the bottom of the Faraday cup and the center point of the rim of the cup.

3. The positioning method according to claim 1, characterized in that, Step S2 includes: Connect the two corner points to construct a reference line; Align the axis of the first Faraday cup with the reference line; Slide the first Faraday cup along the reference line. The installation position of the first Faraday cup is determined in response to the highest concentration of the ion beam gathered by the first Faraday cup.

4. The positioning method according to claim 1, characterized in that, Step S3 includes: The sample ion beam is generated by ionizing the sample gas using the ECR ion source. Under the condition of the accelerating tube voltage U0, the magnetic field current is adjusted to determine the sample ion beam intensity in the first Faraday cup. In response to the sample ion beam intensity reaching its peak value, the adjusted magnetic field current is determined to be the sample magnetic field current I1.

5. The positioning method according to claim 1, characterized in that, Step S4 includes: A first camera is positioned facing the first fluorescent screen; a second camera is positioned facing the second fluorescent screen.

6. The positioning method according to claim 1, characterized in that, Step S4 further includes: Install a first fluorescent screen at the first position; Under the condition of sample magnetic field current I1, the accelerating tube voltage U0 is adjusted so that the sample ion beam has the same trajectory as the Nth ion beam. An image of the first spot where the sample ion beam converges on the first fluorescent screen is acquired by the first camera, and the coordinates of the first spot are determined based on the image.

7. The positioning method according to claim 1, characterized in that, Step S4 includes: A second fluorescent screen is installed in a predetermined direction at the theoretical position of the Nth Faraday cup; Under the condition of sample magnetic field current I1, the accelerating tube voltage U0 is adjusted so that the sample ion beam has the same trajectory as the Nth ion beam. An image of the second spot where the sample ion beam converges on the second fluorescent screen is acquired by a second camera, and the coordinates of the second spot are determined based on the image.

8. The positioning method according to claim 6, characterized in that, The step of acquiring an image of the first spot where the sample ion beam converges on the first fluorescent screen using a first camera, and determining the coordinates of the first spot based on the image, includes: Under dark conditions, the first camera captures a first dark-field image of the first light spot converging on the first fluorescent screen; Under bright field conditions, the first camera captures a first bright field image of the first light spot converging on the first fluorescent screen; The first dark field image is compared with the first bright field image, and the coordinates of the first light spot are determined based on the scribed lines on the first fluorescent screen.

9. The positioning method according to claim 8, characterized in that, The step of acquiring an image of the second spot where the sample ion beam converges on the second fluorescent screen using a second camera, and determining the coordinates of the second spot based on the image, includes: Under dark conditions, the second camera captures a second dark-field image of the second light spot converging on the second fluorescent screen; Under bright field conditions, the second camera captures a second bright field image of the second light spot converging on the second fluorescent screen; The second dark field image is compared with the second bright field image, and the coordinates of the second spot are determined based on the scribed lines on the second fluorescent screen.

10. The positioning method according to claim 1, characterized in that, Step S5 includes: Construct a reference line by connecting the coordinates of the first spot and the coordinates of the second spot; Align the axis of the Nth Faraday cup with the reference line; The Nth Faraday cup is slid along the reference line, and the installation position of the Nth Faraday cup is determined in response to the highest concentration of the ion beam gathered by the Nth Faraday cup.

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