Dispersion elimination method of charged particle beam in interfering magnetic field environment based on electrode plate

Abstract

The present invention provides a method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate, the method comprising the following steps: step one, obtaining magnetic induction intensity and target position; step two, obtaining the emission direction of charged particles of different energies at the electrode plate outlet according to the result in step one; step three, obtaining the optical axis and electric field intensity of the beam according to the result in step two; step four, calculating the energy and target position of charged particles of different energies at the electrode plate outlet according to the result in step three and updating them, obtaining a converged solution after multiple iterations; step five, adjusting the accelerator attitude and setting the electrode plate according to the result in step four, to achieve elimination of dispersion of the charged particle beam. The method of the present invention is highly practical and can be applied to the last stage of various accelerator devices for various charged particles. The method can effectively eliminate dispersion, improve the accuracy of the charged particle beam to the target and the beam flux density, and enhance the beam irradiation effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of accelerator system design, relates to a method for eliminating dispersion, and particularly relates to a method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate. Background Art

[0002] Particle accelerators are used in industrial irradiation processing, sterilization, and cancer treatment. In these applications, the particle beam often requires a small spot size and high flux density at the target. In non-magnetic shielding scenarios, charged particles may be disturbed by external magnetic fields, such as the Earth's magnetic field, during their propagation path. This can cause beam deviation and dispersion at the target.

[0003] The particle beam generated by an actual particle accelerator has a certain energy distribution, so it will produce different path trajectories under the action of a magnetic field. The dispersion effect refers to the fact that particles with different momenta / energy starting from the same object point are distributed at different positions on the image plane, resulting in the beam forming a larger beam spot size and a smaller flux density on the target surface, which is difficult to meet the needs of actual applications. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate, so as to solve the technical problem in the existing technology that the charged particle beam is prone to dispersion.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate, the method comprising the following steps:

[0007] Step 1: Obtain magnetic induction intensity and target location

[0008] Step 2: According to the magnetic induction intensity obtained in step 1 and target location Calculate the emission direction of charged particles with different energies at the electrode plate outlet.

[0009] Step 3: Calculate the optical axis and electric field intensity of the beam according to the emission directions of charged particles of different energies at the electrode plate outlet in step 2.

[0010] Step 4: Calculate the energy of charged particles of different energies at the electrode plate outlet based on the electric field strength obtained in step 3. Calculate the target position based on the beam optical axis and electric field strength obtained in step 3. and update; after multiple iterative updates, a converged solution is obtained, that is, the final electric field intensity, the voltage operating range corresponding to the electric field intensity, and the optical axis of the beam before deflection are obtained.

[0011] Step 5: Adjust the accelerator posture according to the optical axis of the beam before deflection obtained in step 4, and set the electrode plates according to the final electric field strength obtained in step 4 and the voltage working range corresponding to the electric field strength to eliminate the dispersion of the charged particle beam.

[0012] The present invention also has the following technical features:

[0013] Specifically, in step 1, the magnetic induction intensity The corresponding magnetic field is a uniform magnetic field or a segmented uniform magnetic field.

[0014] Specifically, in step 1, the magnetic induction intensity When acquiring, it is necessary to measure the magnetic induction intensity on the charged particle beam path. Take measurements.

[0015] Specifically, in step 4, the calculation process of the converged solution specifically includes the following steps:

[0016] Step 401: Calculate the energy of charged particles of different energies at the electrode plate outlet based on the electric field strength obtained in step 3, and calculate the target position based on the beam optical axis and electric field strength obtained in step 3. and update.

[0017] Step 402: Compare the energy of charged particles with different energies at the electrode plate outlet with the updated target position. Resubstitute into step 2 to update the emission direction at the electrode plate exit.

[0018] Step 403: Substitute the emission direction at the electrode plate outlet updated in step 2 into step 3 to update the electric field strength.

[0019] Step 404: Substitute the updated electric field strength into step 4 to calculate the target position. And update the descendants and enter step 2.

[0020] Repeat steps 401, 402, 403, and 404 for multiple iterations, and then obtain a converged solution, that is, obtain the final electric field intensity, the voltage operating range corresponding to the electric field intensity, and the optical axis of the beam before deflection.

[0021] Specifically, in step four, based on the maximum deflection angle required for charged particles of different energies, the charge of the charged particles, the static mass of the charged particles, the charged particle beam radius, and the charged particle beam energy range, the minimum electrode plate spacing required and the required upper limit of the electric field strength are calculated, thereby obtaining the voltage operating range corresponding to the electric field strength.

[0022] Specifically, the maximum deflection angle required for charged particles of different energies is determined by the magnetic induction intensity. The range of size and target location The range of the size and magnetic induction intensity Direction and target location The range of the angle between the directions is obtained.

[0023] Preferably, in step five, there are two ways to generate the magnitude and direction of the electric field strength. One is two groups of electrode plates that are perpendicular to each other and respectively have voltage sources, which respectively generate electric field strengths with adjustable magnitudes in two directions. The required magnitude and direction of the electric field strength can be obtained by superimposing the approximate vectors of the electric field strengths with adjustable magnitudes in the two directions generated. The other is a group of electrode plates with a voltage source and a rotating mechanism, the rotating mechanism adjusts the direction of the electric field strength, and the voltage source adjusts the magnitude of the electric field strength.

[0024] Specifically, in step five, the method for adjusting the accelerator posture is to adjust the beam direction of the accelerator to the target direction.

[0025] Preferably, the adjustment method is to move the accelerator and the beam optical device as a whole through a two-degree-of-freedom robotic arm, and to ensure that the electric field generated by the electrode plate is always perpendicular to the beam.

[0026] Compared with the prior art, the present invention has the following technical effects:

[0027] (I) The method of the present invention is highly practical and can be applied to the last stage of various accelerator devices for various charged particles. The method can effectively eliminate dispersion, improve the accuracy of the charged particle beam to the target and the beam flux density, and enhance the beam irradiation effect.

[0028] (II) The method of the present invention has strong applicability and can be used to eliminate dispersion at any spatial magnetic field and any target position within a certain range.

[0029] (III) The method of the present invention has strong real-time performance and can perform real-time dispersion elimination and device adjustment according to the changes in the magnetic field in the scene.

[0030] (IV) The present invention can achieve de-dispersion of a charged particle beam in a magnetic field environment by using only two sets of electrode plates or one set of electrode plates plus a rotating mechanism. The device is small in scale, occupies little space, and has good economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the process of eliminating dispersion of charged particle beam in an interfering magnetic field environment based on electrode plates.

[0032] Figure 2 is the emission direction of a single charged particle at the electrode plate exit and the target position Schematic diagram of the angle.

[0033] Figure 3 A diagram illustrating the deflection angle of a single charged particle passing through an electrode plate.

[0034] Figure 4 This is a transmission diagram of a charged particle beam without dedispersion under a spatial interference magnetic field in an embodiment.

[0035] Figure 5 2 is a diagram of the transmission of a charged particle beam in a spatial interference magnetic field after de-dispersion using an electrode plate in an embodiment.

[0036] The specific contents of the present invention are further explained in detail below with reference to the embodiments. DETAILED DESCRIPTION

[0037] It should be noted that, unless otherwise specified, all raw materials and instruments used in the present invention are those known in the art. For example, the accelerator used is a known accelerator. All units of physical quantities used in the present invention are units commonly known in the art.

[0038] The uniform magnetic field in the present invention can also be understood as a near-uniform magnetic field. A near-uniform magnetic field means that the deflection of the magnetic field with respect to the spatial coordinate is small, which also means that the magnetic field is approximately a uniform dipole magnetic field. The near-uniform magnetic field has a small deflection with respect to the spatial coordinate to ensure that the magnetic fields at different positions of the same beam cross section are close.

[0039] In the present invention, the magnetic induction intensity refers to the magnetic induction intensity of the spatial interference magnetic field.

[0040] In the present invention, the target position refers to the position of the target relative to the charged particles at the outlet of the electrode plate.

[0041] In the present invention, the exit velocity refers to the velocity at the exit of the electrode plate.

[0042] In the present invention, the electric field strength refers to the electric field strength of the electrode plate.

[0043] In the present invention, the incident direction refers to the emission speed direction of the charged particles at the initial moment, that is, the speed direction of the charged particles before entering the electrode plate.

[0044] In the present invention, the electrode plate length refers to the corrected length after taking the fringe field into account.

[0045] The method of the present invention can only eliminate the influence of dispersion on the beam spot divergence when reaching the target, and cannot solve the influence of the initial beam divergence angle θ on the beam spot size. Therefore, even if the Coulomb repulsion is ignored, the minimum beam spot divergence radius to the target in theory is greater than

[0046] In accordance with the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0047] Example 1:

[0048] This embodiment provides a method for eliminating dispersion of charged particle beams in an interfering magnetic field environment based on electrode plates, such as Figure 1 As shown, the method includes the following steps:

[0049] Step 1: Obtain magnetic induction intensity and target location

[0050] In step 1, the magnetic induction intensity The corresponding magnetic field is a uniform magnetic field or a segmented uniform magnetic field.

[0051] In step 1, the magnetic induction intensity When acquiring, it is necessary to measure the magnetic induction intensity on the charged particle beam path. Take measurements.

[0052] In step 1, preferably, the magnetic induction intensity When the corresponding magnetic field change is small and the distance is short, only the magnetic induction intensity at a single location is measured. Conversely, measurements are required at multiple points along the charged particle beam path. The weighted results are then used to calculate a near-uniform magnetic field or a segmented near-uniform magnetic field. The minimal temporal variation of the magnetic field ensures that each solution is effective for dedispersion of the charged particle beam over a period of time.

[0053] In this embodiment, the magnetic induction intensity The size is 1mT, the target location The size is 1m.

[0054] In this embodiment, the charged particles are electrons and the energy distribution of the charged particle beam is 0.4-0.6 MeV.

[0055] If the emission direction of the charged particle beam at the electrode plate outlet is directly calculated based on the central energy of the charged particle beam, the transmission and distribution of the charged particle beam to the target are as follows: Figure 4 As shown in the figure (to illustrate the effects of dispersion, the charged particle beam has no divergence angle and no radial distribution, and is initially aligned with the beam optical axis), the charged particle beam size reaching the target is approximately 5 cm, and the target flux will be significantly reduced. Therefore, the charged particle beam needs to be de-dispersed.

[0056] Step 2: According to the magnetic induction intensity obtained in step 1 and target location Calculate the emission direction of charged particles of different energies at the electrode plate outlet. The calculation method for a single charged particle is:

[0057] 1) When the magnetic induction intensity obtained in step 1 When the corresponding magnetic field is a uniform magnetic field:

[0058] i) If the magnetic induction intensity Direction and target location The directions of the electrodes are parallel to each other, and the emission direction of a single charged particle at the electrode plate outlet is the target position. direction.

[0059] ii) If the magnetic induction intensity Direction and target location The directions of are perpendicular to each other, then a single charged particle moves in a circular motion in the space interference magnetic field, and the motion radius R is:

[0060]

[0061] Where:

[0062] R is the motion radius of a single charged particle;

[0063] m0 is the static mass of a single charged particle;

[0064] γ is the relativistic factor;

[0065] v is the emission velocity of a single charged particle;

[0066] B is the magnetic induction intensity size;

[0067] q is the charge of a single charged particle.

[0068] like Figure 2 As shown, perpendicular to the magnetic induction intensity The plane in which the direction of the single charged particle is located can be used to calculate the emission direction and target position of the single charged particle at the electrode plate outlet. The angle between the directions The solution process is:

[0069]

[0070] Where:

[0071] is the emission direction of a single charged particle at the electrode plate exit and the target position The angle between the directions of

[0072] r is the target position size;

[0073] R is the motion radius of a single charged particle;

[0074] B is the magnetic induction intensity size;

[0075] q is the charge of a single charged particle;

[0076] m0 is the static mass of a single charged particle;

[0077] γ is the relativistic factor;

[0078] v is the emission velocity of a single charged particle.

[0079] Figure 2 In the figure, S represents the source and T represents the target.

[0080] Target location is the origin, the target position The direction is x-axis, and the magnetic induction intensity The direction of the z axis is the z axis, and the direction perpendicular to the x axis and z axis is the y axis. The coordinate system is established, and the emission direction of a single charged particle at the outlet of the electrode plate is for:

[0081]

[0082] iii) If the magnetic induction intensity Direction and target location The direction is neither parallel nor perpendicular. Let the angle between the two be α. Then the motion of a single charged particle is decomposed into two parts parallel to the magnetic induction intensity. The direction is perpendicular to the magnetic induction intensity direction.

[0083] Target location is the origin, the magnetic induction intensity The direction is the z-axis, The direction of is the y-axis, and the direction perpendicular to the y-axis and z-axis is the x-axis. Establish a coordinate system, set is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions of is the angle between the projection of the emission direction of a single charged particle at the outlet of the electrode plate on the xoy plane and the x-axis.

[0084] The velocity of a single charged particle along the z-axis is:

[0085] v / / =v cosθ

[0086] Where:

[0087] v / / is the exit velocity of a single charged particle along the z axis;

[0088] v is the emission velocity of a single charged particle;

[0089] is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions.

[0090] The exit velocity of a single charged particle in the xoy plane is:

[0091] v ⊥ =v sinθ

[0092] Where:

[0093] v ⊥ is the emission velocity of a single charged particle in the xoy plane;

[0094] v is the emission velocity of a single charged particle;

[0095] is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions.

[0096] The radius of the circle of a single charged particle in the xoy plane is:

[0097]

[0098] Where:

[0099] R is the radius of the circle of motion of a single charged particle in the xoy plane;

[0100] m0 is the static mass of a single charged particle;

[0101] γ is the relativistic factor;

[0102] v ⊥ is the emission velocity of a single charged particle in the xoy plane;

[0103] B is the magnetic induction intensity size;

[0104] q is the charge of a single charged particle;

[0105] v is the emission velocity of a single charged particle;

[0106] is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions.

[0107] A single charged particle moves along the z-axis to the target location The time required for projection on the z-axis is:

[0108]

[0109] Where:

[0110] t is the movement of a single charged particle from the z axis to the target position The time required for projection on the z-axis;

[0111] r is the target position size;

[0112] α is the magnetic induction intensity Direction and target location The angle between the directions of

[0113] v is the emission velocity of a single charged particle;

[0114] is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions.

[0115] To reach the target position The chord length of the trajectory of a single charged particle in the xoy plane at this moment must be exactly equal to the target position. The projection distance on the z-axis is rsinα, that is:

[0116]

[0117] Where:

[0118] m0 is the static mass of a single charged particle;

[0119] γ is the relativistic factor;

[0120] v is the emission velocity of a single charged particle;

[0121] is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions of

[0122] B is the magnetic induction intensity size;

[0123] q is the charge of a single charged particle;

[0124] r is the target position size;

[0125] α is the magnetic induction intensity Direction and target location The angle between the directions.

[0126] In the above formula, only θ is an unknown quantity, and the minimum solution (the solution whose motion in the xoy plane does not exceed half a period) can be obtained by bisection.

[0127] The angle between the projection of the emission direction of a single charged particle at the outlet of the electrode plate on the xoy plane and the x-axis is:

[0128]

[0129] Where:

[0130] is the angle between the projection of the emission direction of a single charged particle at the outlet of the electrode plate on the xoy plane and the x-axis;

[0131] r is the target position size;

[0132] α is the magnetic induction intensity Direction and target location The angle between the directions of

[0133] R is the radius of the circle of motion of a single charged particle in the xoy plane;

[0134] B is the magnetic induction intensity size;

[0135] q is the charge of a single charged particle;

[0136] m0 is the static mass of a single charged particle;

[0137] r is the target position size;

[0138] v is the emission velocity of a single charged particle;

[0139] is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions.

[0140] Finally, the emission direction of a single charged particle at the electrode plate outlet is obtained for

[0141]

[0142] After calculating the emission direction of a single charged particle at the electrode plate outlet, the angle δ between the emission directions of charged particles with different energies at the electrode plate outlet is calculated based on the emission directions of two charged particles with different energies at the electrode plate outlet.

[0143] 2) When the magnetic induction intensity obtained in step 1 When the corresponding magnetic field is a segmented uniform magnetic field:

[0144] The first solution is performed according to the above uniform magnetic field solution method, and then the emission direction at the electrode plate outlet obtained by the solution is substituted into the segmented uniform magnetic field, and the target position is gradually adjusted to obtain the emission direction of the particles at the electrode plate outlet in this case.

[0145] In this embodiment, the magnetic induction intensity Direction and target location The directions are perpendicular to each other, and the effective length of the electrode plate used is 0.1m; the target position is the origin, the target position The direction is x-axis, and the magnetic induction intensity The direction is the z-axis, and the direction perpendicular to the x-axis and z-axis is the y-axis. A coordinate system is established.

[0146] Then, the emission direction of electrons at the electrode plate outlet is calculated when the electron energy is 0.4MeV. When the electron energy is 0.6MeV, the direction of electron emission at the electrode plate outlet is The angle between the two emission directions at the electrode plate outlet is δ=0.048 rad.

[0147] Step 3: According to the emission direction of charged particles with different energies at the electrode plate outlet in step 2, the optical axis of the beam and the electric field strength are calculated to make the emission direction of charged particles with different energies at the electrode plate outlet close to the incident direction. Figure 3 shown.

[0148] The specific solution method is:

[0149] The motion equation of charged particles in the electrode plate is:

[0150]

[0151] Where:

[0152] p x is the projection of the momentum of a single charged particle on the x-axis;

[0153] p y is the projection of the momentum of a single charged particle on the y-axis;

[0154] p z is the projection of the momentum of a single charged particle on the z-axis;

[0155] q is the charge of a single charged particle;

[0156] E is the magnitude of the electric field strength;

[0157] t is the time that the charged particles stay in the electrode plates.

[0158] After calculation, the deflection angle of the charged particle after passing through the electrode plate is:

[0159]

[0160] Where:

[0161] is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions of

[0162] c is the speed of light;

[0163] v0 is the velocity of a single charged particle before it enters the electrode plate;

[0164] h is the distance between the electrode plates;

[0165] q is the charge of a single charged particle;

[0166] E is the magnitude of the electric field strength;

[0167] p0 is the momentum of a single charged particle before it enters the electrode plate;

[0168] D is the length of the electrode plate.

[0169] Substituting single charged particles of different energies into the above formula, the corresponding deflection angle under a specific electric field strength can be obtained as:

[0170]

[0171] Where:

[0172] is the emission direction and magnetic induction intensity of a single charged particle at the electrode plate outlet The angle between the directions of

[0173] c is the speed of light;

[0174] v 01 It is the velocity of a single charged particle with lower energy before entering the electrode plate;

[0175] h is the distance between the electrode plates;

[0176] q is the charge of a single charged particle;

[0177] E is the magnitude of the electric field strength;

[0178] p 01 It is the momentum of a single charged particle with lower energy before entering the electrode plate;

[0179] D is the length of the electrode plate;

[0180] v 02 It is the velocity of a single charged particle with higher energy before entering the electrode plate;

[0181] p 02 It is the momentum of a single charged particle with higher energy before it enters the electrode plate.

[0182] By using the bisection method, we can determine the electric field strength required to produce an angle δ between the emission directions of charged particles of different energies at the electrode plate exit. Based on the deflection angle of the charged particle at this electric field strength, we can determine the direction of the charged particle before deflection, which is the optical axis of the beam. Because the energy dispersion of charged particles is relatively small, the emission direction of charged particles at the electrode plate exit can be assumed to be approximately linearly related to their energy.

[0183] In this embodiment, after performing the dichotomy, the required electric field strength E = 1.408 MV / m is obtained. Under this electric field, the deflection angle θ1 of a 0.4 MeV electron is 0.167 rad, and the optical axis of the beam before deflection is

[0184]

[0185] Step 4: Calculate the energy of charged particles of different energies at the electrode plate outlet based on the electric field strength obtained in step 3. Calculate the target position based on the beam optical axis and electric field strength obtained in step 3. and update; after multiple iterative updates, a converged solution is obtained, that is, the final electric field intensity, the voltage operating range corresponding to the electric field intensity, and the optical axis of the beam before deflection are obtained.

[0186] In step 4, the calculation process of the converged solution specifically includes the following steps:

[0187] Step 401: Calculate the energy of charged particles of different energies at the electrode plate outlet based on the electric field strength obtained in step 3, and calculate the target position based on the beam optical axis and electric field strength obtained in step 3. and update.

[0188] Step 402: Compare the energy of charged particles with different energies at the electrode plate outlet with the updated target position. Resubstitute into step 2 to update the emission direction at the electrode plate exit.

[0189] Step 403: Substitute the emission direction at the electrode plate outlet updated in step 2 into step 3 to update the electric field strength.

[0190] Step 404: Substitute the updated electric field strength into step 4 to calculate the target position. And update the descendants and enter step 2.

[0191] Repeat steps 401, 402, 403, and 404 for multiple iterations, and then obtain a converged solution, that is, obtain the final electric field intensity, the voltage operating range corresponding to the electric field intensity, and the optical axis of the beam before deflection.

[0192] In step 4, based on the maximum deflection angle required for charged particles of different energies, the charge of the charged particles, the static mass of the charged particles, the radius of the charged particle beam, and the energy range of the charged particle beam, the minimum electrode plate spacing required and the upper limit of the required electric field strength are calculated, thereby obtaining the voltage operating range corresponding to the electric field strength.

[0193] The maximum deflection angle required for charged particles of different energies is determined by the magnetic induction intensity. The range of size and target location The range of the size and magnetic induction intensity Direction and target location The range of the angle between the directions is obtained.

[0194] Due to the deflection of the electrode plate electric field and the change of the beam optical axis, the position of the charged particles at the electrode plate outlet moves, and the target position will also change accordingly. In addition, the electric field will cause the energy of the charged particles to change. Therefore, it is necessary to calculate the target position corresponding to the optical axis of the beam according to step three. The energy of the charged particles after leaving the electrode plate is recalculated and obtained after multiple iterations.

[0195] In this embodiment, since the electric field increases the electron energy, under the electric field strength obtained in step 3, it is calculated that the energy of a 0.4MeV electron becomes 0.409MeV and the energy of a 0.6MeV electron becomes 0.606MeV at the electrode plate outlet.

[0196] At the same time, the electrode plate changes the electron exit position. It is calculated that under the electric field strength and beam optical axis obtained in step 3, the positions of the electrode plate exits of 0.4MeV electrons and 0.6MeV electrons become (-0.0003, 0.0084, 0) and (-0.0002, 0.0060, 0) respectively. Then the target position Updated to as well as The changed charged particle energy and target position Resubstitute to calculate the emission direction at the electrode plate exit, and then update the required electric field strength, electron energy at the electrode plate exit and target position After multiple iterations of this method, a converged solution can be obtained, that is, the electric field intensity E = 0.956MV / m and the optical axis of the beam before deflection

[0197]

[0198] Step 5: Adjust the accelerator posture according to the optical axis of the beam before deflection obtained in step 4, and set the electrode plates according to the final electric field strength obtained in step 4 and the voltage working range corresponding to the electric field strength to eliminate the dispersion of the charged particle beam.

[0199] In step five, the magnitude and direction of the electric field intensity are generated in two ways: one uses two sets of mutually perpendicular electrode plates, each equipped with a voltage source, to generate adjustable electric field intensities in two directions. The desired magnitude and direction of the electric field intensity are obtained by superimposing the two generated adjustable electric field intensities in the two directions approximately. The other uses a set of electrode plates equipped with a voltage source and a rotating mechanism. The rotating mechanism adjusts the direction of the electric field intensity, while the voltage source adjusts the magnitude. This eliminates the effects of dispersion, achieving precise targeting, a smaller beam spot radius, and a higher flux density.

[0200] In step five, the beam direction itself needs to be adjusted to point toward the target.

[0201] In step five, the direction of adjustment is achieved by moving the accelerator and beam optical device as a whole through a mechanical device with two degrees of freedom, and the electric field generated by the electrode plate is always perpendicular to the beam.

[0202] When the target is confined to a small range in the beam pointing direction, no beam pointing adjustment is performed.

[0203] In this embodiment, after setting the electric field intensity and beam optical axis obtained in step 4, the beam transmission and target distribution can be obtained as follows: Figure 5 As shown in the figure, the target position The size is less than 1mm, compared to Figure 4 In the case of an undispersed charged particle beam, the target position The size of the target is significantly reduced and the flux to the target is significantly enhanced.

Claims

1. A method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate, characterized in that: The method comprises the following steps: Step 1: Obtain magnetic induction intensity and target location ; Step 2: According to the magnetic induction intensity obtained in step 1 and target location , calculate the emission direction of charged particles with different energies at the outlet of the electrode plate; Step 3: Calculate the optical axis and electric field intensity of the beam according to the emission direction of charged particles of different energies at the electrode plate outlet in Step 2; Step 4: Calculate the energy of charged particles of different energies at the electrode plate outlet based on the electric field strength obtained in step 3. Calculate the target position based on the beam optical axis and electric field strength obtained in step 3. and update; after multiple iterations, a converged solution is obtained, that is, the final electric field intensity, the voltage operating range corresponding to the electric field intensity, and the optical axis of the beam before deflection are obtained; Step 5: Adjust the accelerator posture according to the optical axis of the beam before deflection obtained in step 4, and set the electrode plates according to the final electric field strength obtained in step 4 and the voltage working range corresponding to the electric field strength to eliminate the dispersion of the charged particle beam.

2. The method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate according to claim 1, characterized in that: In step 1, the magnetic induction intensity The corresponding magnetic field is a uniform magnetic field or a segmented uniform magnetic field.

3. The method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate according to claim 1, wherein: In step 1, the magnetic induction intensity When acquiring, it is necessary to measure the magnetic induction intensity on the charged particle beam path. Take measurements.

4. The method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate according to claim 1, wherein: In step 4, the calculation process of the converged solution specifically includes the following steps: Step 401: Calculate the energy of charged particles of different energies at the electrode plate outlet based on the electric field strength obtained in step 3, and calculate the target position based on the beam optical axis and electric field strength obtained in step 3. and update; Step 402: Compare the energy of charged particles with different energies at the electrode plate outlet with the updated target position. Resubstitute into step 2 to update the emission direction at the electrode plate exit; Step 403: Substitute the emission direction at the electrode plate outlet updated in step 2 into step 3 to update the electric field strength; Step 404: Substitute the updated electric field strength into step 4 to calculate the target position. And update the offspring into step 2; Repeat steps 401, 402, 403, and 404 for multiple iterations, and then obtain a converged solution, that is, obtain the final electric field intensity, the voltage operating range corresponding to the electric field intensity, and the optical axis of the beam before deflection.

5. The method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate according to claim 1, wherein: In step 4, based on the maximum deflection angle required for charged particles of different energies, the charge of the charged particles, the static mass of the charged particles, the radius of the charged particle beam, and the energy range of the charged particle beam, the minimum electrode plate spacing required and the upper limit of the required electric field strength are calculated, thereby obtaining the voltage operating range corresponding to the electric field strength.

6. The method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate according to claim 5, characterized in that: The maximum deflection angle required for charged particles of different energies is determined by the magnetic induction intensity. The range of size and target location The range of the size and magnetic induction intensity Direction and target location The range of the angle between the directions is obtained.

7. The method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate according to claim 1, wherein: In step five, there are two ways to generate the magnitude and direction of the electric field strength. One is to use two sets of electrode plates that are perpendicular to each other and each has a voltage source, which generate electric field strengths with adjustable magnitudes in two directions respectively. The required magnitude and direction of the electric field strength can be obtained by superimposing the approximate vectors of the electric field strengths with adjustable magnitudes in the two directions generated. The other is to use a set of electrode plates with a voltage source and a rotating mechanism, where the rotating mechanism adjusts the direction of the electric field strength and the voltage source adjusts the magnitude of the electric field strength.

8. The method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate according to claim 1, wherein: In step five, the method for adjusting the accelerator posture is to adjust the beam direction of the accelerator to the target direction.

9. The method for eliminating dispersion of a charged particle beam in an interfering magnetic field environment based on an electrode plate according to claim 8, characterized in that: The method for adjusting the accelerator posture is to move the accelerator and the beam optical device as a whole through a two-degree-of-freedom mechanical arm, and to ensure that the electric field generated by the electrode plate is always perpendicular to the beam.

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