Laser acceleration star-shaped beam elimination method, device and equipment

Abstract

The invention discloses a laser acceleration star beam elimination method, device and equipment. The method comprises the following steps: acquiring an initial beam shape of an initial beam distributed at a target position; the initial beam current distribution is beam current distribution after the preset proton beam current passes through the focusing section with the triple electric quadrupole magnet group; determining whether the initial beam shape is distorted to form a star beam; if it is determined that the initial beam shape is distorted to form a star beam, determining a target magnetic field gradient required for adjusting the initial beam shape to a target beam shape by adopting preset beam dynamics simulation software; and adjusting the magnetic field gradient of the triple electric quadrupole magnet group according to the target magnetic field gradient so as to eliminate the star beam and obtain target beam current distribution. According to the embodiment of the invention, elimination of the star-shaped beam of laser acceleration can be quickly realized.

Description

Technical Field

[0001] This application belongs to the field of laser proton accelerators, and particularly relates to a method, apparatus and equipment for eliminating star-shaped beams in laser acceleration. Background Technology

[0002] A laser-driven proton accelerator is a device that uses the interaction of ultrashort, ultra-intense lasers and plasma to obtain high-energy electron and ion beams.

[0003] The Compact Laser Plasma Accelerator (CLAPA) is an ultra-miniature laser-plasma accelerator developed by Peking University. It utilizes the interaction between an ultra-intense laser and plasma to generate a high-gradient electric field, enabling the acceleration of electrons, protons, and heavy ions. During the beamline propagation phase of CLAPA, the high-energy, diffused laser beam experiences different velocities in the horizontal and vertical directions as it passes through a quadrupole magnet. This causes the initially circular beam spot to stack into a star-shaped beam distribution as it passes the quadrupole magnet. This star-shaped beam distribution persists until the rear of the beamline, severely impacting beam quality.

[0004] Currently, star beam elimination is mostly achieved by adjusting the four-octet magnets based on the experience of relevant staff, which is tedious and difficult to do in one step. Summary of the Invention

[0005] This application provides a method, apparatus, and device for eliminating laser-accelerated star-shaped beams, which can quickly eliminate laser-accelerated star-shaped beams.

[0006] On one hand, embodiments of this application provide a method for eliminating laser-accelerated star-shaped beams, including: Obtain the initial beam shape at the target location; the initial beam distribution is a preset beam distribution after the proton beam passes through the focusing section with a triple quadrupole magnet assembly. Determine whether the initial beam shape is distorted to form a star-shaped beam; If it is determined that the initial beam shape distortion forms a star-shaped beam, then the target magnetic field gradient required to adjust the initial beam shape to the target beam shape is determined using preset beam dynamics simulation software; The magnetic field gradient of the triple quadrupole magnet assembly is adjusted according to the target magnetic field gradient to eliminate the star-shaped beam and obtain the target beam distribution.

[0007] As an optional implementation, the step of using preset beam dynamics simulation software to determine the target magnetic field gradient required to adjust the initial beam shape to the target beam shape includes: The target beam shape is input into a preset beam dynamics simulation software, and the target magnetic field gradient corresponding to the target beam shape is calculated using the preset beam dynamics simulation software; the target magnetic field gradient is the magnetic field gradient of a triple electric quadrupole magnet assembly.

[0008] As an optional implementation, the step of calculating the target magnetic field gradient corresponding to the target beam shape using preset beam dynamics simulation software includes: Input the initial beam distribution and its corresponding initial magnetic field gradient into the preset beam dynamics simulation software; Under the initial magnetic field gradient, if the initial beam distribution has a focal length greater than the focal length in the vertical direction, the magnetic field gradient is adjusted to increase the degree of over-focusing in the horizontal direction and the degree of under-focusing in the vertical direction until the initial beam shape changes to the target beam shape, thereby obtaining the target magnetic field gradient. Under the initial magnetic field gradient, if the initial beam distribution has a focal length in the vertical direction that is less than that in the horizontal direction, the magnetic field gradient is adjusted to increase the degree of over-focusing in the vertical direction and the degree of under-focusing in the horizontal direction until the initial beam shape changes to the target beam shape, thereby obtaining the target magnetic field gradient.

[0009] As an optional implementation, adjusting the magnetic field gradient of the triple electric quadrupole magnet assembly according to the target magnetic field gradient includes: The target current intensity is calculated based on the magnet excitation formula of the triple electric quadrupole magnet assembly and the target magnetic field gradient. The current intensity of the triple electric quadrupole magnet assembly is set to the target current intensity so that the magnetic field gradient of the triple electric quadrupole magnet assembly is the target magnetic field gradient.

[0010] As an optional implementation, determining whether the initial beam shape is distorted to form a star-shaped beam includes: Calculate the star-shaped distortion of the initial beam shape compared to a standard uniform circular beam spot; If the star-shaped distortion degree is greater than or equal to the preset distortion threshold, then the initial beam shape distortion is determined to form a star-shaped beam; If the star-shaped distortion degree is less than the preset distortion threshold, then it is determined that the initial beam shape has not been distorted to form a star-shaped beam.

[0011] As an optional implementation, calculating the star-shaped distortion degree of the initial beam shape compared to a standard uniform circular beam spot includes: Determine the number of the first particles falling into the reference annular region in the initial beam shape; Determine the number of second particles falling into the reference fan-shaped region in the initial beam shape; the reference fan-shaped region is the fan-shaped region in the reference annular region from a first preset angle to a second preset angle; The star-shaped distortion degree is calculated based on the first particle number, the second particle number, the reference ring particle number, and the reference fan-shaped particle number; the reference ring particle number is the number of particles of the standard uniform circular beam spot in the reference ring region; the reference fan-shaped particle number is the number of particles of the standard uniform circular beam spot in the reference fan region.

[0012] As an optional implementation, the method further includes: If it is determined that the initial beam shape distortion forms a star-shaped beam, and it is determined that the energy of the preset proton beam is greater than an energy threshold, then a target scatterer is set at the beam exit to perform star-shaped beam elimination processing on the initial beam distribution to obtain a target beam distribution; wherein, the thickness of the target scatterer is determined according to the energy of the preset proton beam.

[0013] As an optional implementation, the target scatterer includes a lead scatterer and an organic scatterer; the organic scatterer has a first concave surface and a second concave surface facing away from each other; the lead scatterer has a convex surface and a flat surface facing away from each other; the convex surface fits into the second concave surface, and the flat surface faces the beam outlet of the triple quadrupole magnet assembly.

[0014] On the other hand, embodiments of this application provide a laser-accelerated star beam elimination device, comprising: The acquisition module is used to acquire the initial beam shape at the target location; the initial beam distribution is a preset beam distribution after the proton beam passes through the focusing section with a triple electric quadrupole magnet assembly; The first determining module is used to determine whether the initial beam shape is distorted to form a star-shaped beam; The second determining module is used to determine the target magnetic field gradient required to adjust the initial beam shape to the target beam shape if it is determined that the initial beam shape distortion forms a star beam. The processing module is used to adjust the magnetic field gradient of the triple electric quadrupole magnet group according to the target magnetic field gradient in order to eliminate the star beam and obtain the target beam distribution.

[0015] In another aspect, embodiments of this application provide an electronic device, the device including: a processor and a memory storing computer program instructions; When the processor executes computer program instructions, it implements any one of the laser-accelerated star beam elimination methods mentioned above.

[0016] In another aspect, embodiments of this application provide a computer-readable storage medium storing computer program instructions, which, when executed by a processor, implement any of the laser-accelerated star beam elimination methods described above.

[0017] In another aspect, embodiments of this application provide a computer program product in which instructions are executed by the processor of an electronic device, causing the electronic device to perform any of the laser-accelerated star beam elimination methods described above.

[0018] The laser-accelerated star beam elimination method, apparatus, and device of this application embodiment obtain the initial beam shape of the initial beam distribution at the target location; the initial beam distribution is the beam distribution of a preset proton beam after passing through the focusing section of a triple electric quadrupole magnet group; determine whether the initial beam shape is distorted to form a star beam; if it is determined that the initial beam shape is distorted to form a star beam, then a preset beam dynamics simulation software is used to determine the target magnetic field gradient required to adjust the initial beam shape to the target beam shape; adjust the magnetic field gradient of the triple electric quadrupole magnet group according to the target magnetic field gradient to eliminate the star beam and obtain the target beam distribution; since the preset beam dynamics simulation software can quickly determine the target magnetic field gradient, the current intensity of the triple electric quadrupole magnet group can be quickly adjusted according to the target magnetic field gradient to quickly eliminate the laser-accelerated star beam. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram showing the changes of the values ​​of a and b of an ellipse as a function of energy after a proton beam passes through a triple-electric quadrupole magnet assembly. Figure 2 A schematic flowchart of a laser-accelerated star beam elimination method provided in one embodiment of this application; Figure 3 This is a schematic diagram of the initial beam shape in one example of this application; Figure 4 This is a schematic diagram of the target beam shape in one example of this application; Figure 5 This is a schematic diagram of the initial beam shape in one example of this application; Figure 6 This is a schematic diagram of the target beam shape in one example of this application; Figure 7 This is a schematic diagram of the structure of a target scatterer in one example of this application; Figure 8 A schematic diagram of the structure of a laser-accelerated star beam elimination device provided in yet another embodiment of this application; Figure 9 This is a schematic diagram of the hardware structure of an electronic device provided in yet another embodiment of this application. Detailed Implementation

[0021] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0023] First, the prior art involved in this application will be described.

[0024] Laser-driven proton accelerators have attracted widespread attention and continuous research from scientists worldwide in recent years due to their enormous application potential in numerous fields such as materials science, imaging, and tumor diagnosis and treatment. Currently, the most mature mechanisms are target-back-sheath field acceleration (TNSA) and radiation pressure acceleration (RPA). In TNSA, a relativistically intense laser irradiates a solid-density target, transferring energy to electrons and generating a large number of hot electrons. This results in the formation of an extremely high-gradient accelerating field, capable of accelerating protons to high energies on a spatial scale of tens of micrometers. Laser-accelerated proton beams have many advantages, such as small source size and low initial emittance. However, the rapid diffusion of the electron layer and various instabilities during acceleration, such as Coulomb explosions, Rayleigh-Taylor instabilities, Weibel instabilities, and various nonlinear effects, lead to large energy dispersion and large divergence in the proton beam. Based on these beam characteristics, designing beamlines to collect and shape the beam is crucial for downstream applications.

[0025] CLAPA is an ultra-miniature laser-plasma accelerator developed by Peking University, comprising two devices: CLAPAI and CLAPAII. The inventors discovered that in CLAPA, due to the different horizontal and vertical velocities of the high-energy laser-accelerated beam as it passes through a quadrupole magnet, the initially circular beam spot stacks into a star-shaped beam distribution as it passes the magnet. This star-shaped beam distribution persists to the rear of the beamline, severely impacting beam quality.

[0026] However, currently, star beam elimination is mostly achieved by adjusting the four-octet magnets based on the experience of relevant staff, which is tedious and difficult to do in one step.

[0027] The following will describe the process by which the inventors discovered the star-shaped beam distribution.

[0028] In CLAPAI, the inventors used an off-axis parabolic mirror with an f / 3.5 aperture to focus a 30 femtosecond laser pulse with a wavelength of 800 nm into a focal spot with a diameter of 5 μm (FWMH). This focal spot contains approximately 30% of the total laser energy, meaning the laser intensity corresponding to a target energy of 1.3 J is approximately 6 × 10^19 W / cm². The laser pulse is incident on a 2.5 μm thick aluminum target at an incident angle of 30° to the target normal. The initially accelerated TNSA proton beam has an exponentially decaying energy distribution, with a cutoff energy of approximately 6.5 MeV and an dispersion of several hundred mrad. The accelerated proton beam exits along the target back normal and is subsequently collected and focused by a set of triplet electric quadrupole lenses (Q1, Q2, Q3), where Q1 and Q3 focus in the x-direction and Q2 focuses in the y-direction. The triplet electric quadrupole magnets have a proton beam acceptance of approximately 50 mrad.

[0029] After the proton beam is collected and focused by a triple electric quadrupole magnet array, a scintillator detector is placed 2.5 m from the exit point to detect the beam spot. The scintillator detector detects that the proton beam forms a star-shaped beam distribution after being collected and focused by the triple electric quadrupole magnet array.

[0030] A 15 µm thick aluminum film is placed in front of the plastic scintillator (EJ-212) to block the scattered light from the main laser and improve the signal-to-noise ratio. The plastic scintillator is a material formed by polymerizing a first luminescent material and a second luminescent material into an organic shield. The basic detection principle of the scintillator detector is that when high-energy ions propagate within the scintillator, they excite secondary electrons, causing the scintillator molecules to be in an ionized or excited state. When the scintillator de-excites, it emits photons. Timely collection and detection of these photons yields ion information. Furthermore, the scintillator cannot distinguish between proton beams of different energies; therefore, the measurement result is the superposition of the distributions of all energy beams.

[0031] The inventors discovered that because the proton beam accelerated by the TNSA mechanism has a wide energy spectrum, and the proton beam is generally collected and focused by a triple electric quadrupole magnet array on the beamline, the trajectory of the proton in the quadrupole field depends on the normalized quadrupole field strength K1.

[0032] Wherein, K1 is defined as K1= e is the elementary charge, P0 is the particle momentum that transmits energy to the beam center, and B is the magnetic induction intensity.

[0033] Under the same magnetic field gradient setting, particles with different energies have different K1 values, resulting in different trajectories. Since the size of the laser-accelerated beam source is on the order of micrometers, the beam exiting can be considered as a point source. The equation for the transverse beam spot cross-section at the entrance of the triple electric quadrupole magnet assembly is x0^2 + y0^2 = R^2, and the divergence angle can be represented by x0 / D and y0 / D, where D is the distance from the target point to the entrance of the triple electric quadrupole magnet assembly. Using relevant theories of beam dynamics, the transmission matrix of the triple electric quadrupole magnet assembly is calculated under the thin lens approximation. After transmission through the triple electric quadrupole magnet assembly, the equation for the transverse beam cross-section at a distance f from the exit of the triple electric quadrupole magnet assembly becomes x1^2 / a^2 + y1^2 / b^2 = 1.

[0034] In the formula, x1 and y1 are the particle coordinates at the exit of the triple electric quadrupole magnet assembly; a,b = a,b(E,H1,H2,H3,d,L,f): E is the proton kinetic energy; H1, H2, and H3 are the field gradients of the three quadrupole magnets, respectively; d is the drift node length of the triple electric quadrupole magnet assembly; L is the length of the three quadrupole magnets; and f is the drift distance after passing through the triple electric quadrupole magnet assembly. Since the specific forms of a and b are complex, being a hybrid polynomial of proton energy and magnet sequence structure, their specific forms are not listed here.

[0035] In summary, the inventors discovered that a proton beam accelerated by a laser, which can be considered a point source, forms a regular ellipse after passing through a triple-electric quadrupole magnet array. The shape of this ellipse depends on the energy of the proton beam and the choice of the magnet sequence structure. The formation of a star-shaped beam is precisely due to the superposition of different ellipses of different shapes after particles of different energies pass through the triple-electric quadrupole magnet array.

[0036] The inventors used a pre-defined beam dynamics simulation software to simulate and analyze the formation of the star-shaped beam and the rotational distortion of the beam. In the software, the proton beam center energy was set to 100 MeV, the RMS energy dispersion to 5 MeV, and the beam divergence angle to 50 mrad. A magnet sequence structure was used to focus the 100 MeV protons into a small circular beam spot.

[0037] Figure 1 This is a schematic diagram illustrating the changes in the values ​​of a and b of an ellipse as a function of energy after a proton beam passes through a triple-electric quadrupole magnet assembly. Figure 1 As shown, under the established magnet sequence structure, for a monoenergetic proton beam, at an energy of 95 MeV, b is much larger than a. As the energy increases, a first decreases and then increases, while b gradually decreases. Therefore, the major axis of the ellipse gradually changes from the y-axis to the x-axis. For protons deviating from the central energy, high-energy protons are focused into an ellipse with its major axis in the x-direction, while low-energy protons are focused into an ellipse with its major axis in the y-direction. The superposition of these different energy particle distributions forms a star-shaped beam pattern.

[0038] The inventors, through simulating the beam dynamics of monoenergetic proton beams with energies of 95 MeV, 100 MeV, and 105 MeV, discovered that focusing a small beam spot more easily produces a star-shaped beam. This is because, when focusing a beam with large energy dispersion into a small beam spot, efforts are made to ensure that the focal points of different energy beams in the x or y directions are as close as possible to the same longitudinal position. However, the focal positions of different energy beams in the x and y directions, as well as the rates of change of these focal positions with energy, differ. Taking the beam propagation direction as the z-axis, the focal positions in both the x and y directions shift towards the z-axis as energy increases, but the shift rate in the y-direction is less than that in the x-direction. Therefore, when circular proton beams of different energies pass through a triple quadrupole magnet array, if the focal points in the x or y directions are as close as possible to the same longitudinal position, it will lead to under-focusing or over-focusing of the different energy beams in the other direction, resulting in the stacking of these different energy beam envelopes to form a star-shaped beam. The small beam spot can be a beam spot with a diameter of less than 5 mm.

[0039] To address the problems of the prior art, embodiments of this application provide a method, apparatus, and device for eliminating laser-accelerated star-shaped beams. The method for eliminating laser-accelerated star-shaped beams provided in this application is first described below; this method is executed by electronic equipment.

[0040] Figure 2 This is a schematic flowchart illustrating a laser-accelerated star beam elimination method according to one embodiment of this application. Figure 2 As shown, one embodiment of this application provides a laser-accelerated star beam elimination method including steps 101 to 104.

[0041] Step 101: Obtain the initial beam shape at the target location; the initial beam distribution is the preset beam distribution after the proton beam passes through the focusing section with a triple quadrupole magnet assembly.

[0042] In this embodiment, the preset proton beam can be a laser-accelerated proton beam with a preset energy. The triple electric quadrupole magnet assembly can be the beam focusing structure in CLAPAI or CLAPAII. The triple electric quadrupole magnet assembly includes three electric quadrupole magnets connected in series, which generate a magnetic field using current. In CLAPAI, the inlet of the triple electric quadrupole magnet assembly is the outlet of the beamline collection section. After being focused by the triple electric quadrupole magnet assembly, the proton stream flows to the beam application end. In CLAPAII, the inlet of the triple electric quadrupole magnet assembly is connected to the outlet of the beamline collection section. After being focused by the triple electric quadrupole magnet assembly, the proton stream flows to the beam shaping section. After being focused by the triple electric quadrupole magnet assembly, the preset proton beam forms an initial beam distribution. The target position refers to the application end in CLAPAI or the inlet of the beam shaping section in CLAPAII, and the target position is a plane perpendicular to the beam transmission direction.

[0043] In one embodiment of this application, the electronic device can determine the initial beam shape based on beam spot detection results at the target location. The beam spot detection results may include the beam spot shape of the initial beam distribution at the target location. The electronic device can determine the beam spot shape of the initial beam distribution at the target location as the initial beam shape.

[0044] For example, the electronic device may include a detection component disposed at the target location. The detection component is used to detect the initial beam current distribution in the beam spot at the target location and obtain a beam spot detection result. The electronic device obtains the beam spot detection result through the detection component. Alternatively, a beam spot detector may be disposed at the target location. The beam spot detector is used to detect the initial beam current distribution in the beam spot at the target location, obtain a beam spot detection result, and can send the beam spot detection result to the electronic device. The electronic device receives the beam spot detection result sent by the beam spot detector. The beam spot detector may be a scintillator detector or a fluorescent target.

[0045] Step 102: Determine whether the initial beam shape is distorted to form a star-shaped beam.

[0046] In another embodiment of this application, step 102, “determining whether the initial beam shape is distorted to form a star beam”, includes steps 501 to 503.

[0047] Step 501: Calculate the star-shaped distortion of the initial beam shape compared to a standard uniform circular beam spot.

[0048] In this embodiment, the star-shaped distortion can be calculated based on the particle distribution in the initial beam shape and a preset distortion formula. The preset distortion formula is a predefined formula used to evaluate the star-shaped degree of the beam distribution.

[0049] Step 502: If the star-shaped distortion degree is greater than or equal to the preset distortion threshold, then the initial beam shape distortion is determined to form a star-shaped beam.

[0050] Step 503: If the star-shaped distortion degree is less than the preset distortion threshold, then it is determined that the initial beam shape is not distorted and forms a star-shaped beam.

[0051] The laser-accelerated star beam elimination method provided in this embodiment can quickly evaluate the degree of star distribution of the initial beam shape by calculating the star distortion degree of the initial beam shape compared with a standard uniform circular beam spot. If the star distortion degree is greater than or equal to a preset distortion threshold, it is determined that the initial beam shape has been distorted to form a star beam. If the star distortion degree is less than the preset distortion threshold, it is determined that the initial beam shape has not been distorted to form a star beam. Thus, it can quickly determine whether the initial beam shape has been distorted to form a star beam.

[0052] In one embodiment of this application, the preset star distortion formula satisfies: .

[0053] In the formula, n is the number of particles in the fan-shaped region from 1 / 2 beam spot radius to beam spot radius, with an angle of 22.5° to 67.5°; N is the number of particles in the entire annular region from 1 / 2 beam spot radius to beam spot radius; 8 is the ratio of n to N when the beam distribution is a standard uniform distribution; SL is the star distortion degree.

[0054] Step 103: If it is determined that the initial beam shape distortion forms a star-shaped beam, then the target magnetic field gradient required to adjust the initial beam shape to the target beam shape is determined using preset beam dynamics simulation software.

[0055] In beam dynamics, there exists a physical relationship between the magnetic field strength of the triple electric quadrupole magnet assembly and the final beam distribution, determined by the beam's inherent characteristics and the overall transmission line optical structure. Pre-defined beam dynamics simulation software can simulate this physical relationship to model the beam propagation process and determine the output beam distribution. Furthermore, this software can be used to calculate the target magnetic field gradient required to adjust the initial beam shape to the target beam shape. The target magnetic field gradient is the magnetic field gradient required for the triple electric quadrupole magnet assembly to focus a pre-defined proton beam to obtain the target beam shape.

[0056] Step 104: Adjust the current intensity of the triple quadrupole magnet assembly according to the target magnetic field gradient to eliminate the star beam and obtain the target beam distribution.

[0057] In this embodiment, the magnetic field gradient of the three-pole electric quadrupole magnet group is related to its current intensity. Therefore, the target current intensity corresponding to the magnetic field gradient of the three-pole electric quadrupole magnet group can be calculated, and then the current intensity of the three-pole electric quadrupole magnet group can be adjusted to the target current intensity so that the magnetic field gradient of the three-pole electric quadrupole magnet group is the target magnetic field gradient.

[0058] The laser-accelerated star beam elimination method provided in this embodiment obtains the initial beam shape at the target location; the initial beam distribution is the beam distribution of a preset proton beam after passing through the focusing section of a triple electric quadrupole magnet assembly; it determines whether the initial beam shape is distorted to form a star beam; if it is determined that the initial beam shape is distorted to form a star beam, a preset beam dynamics simulation software is used to determine the target magnetic field gradient required to adjust the initial beam shape to the target beam shape; the current intensity of the triple electric quadrupole magnet assembly is adjusted according to the target magnetic field gradient to eliminate the star beam and obtain the target beam distribution; since the preset beam dynamics simulation software can quickly determine the target magnetic field intensity, the magnetic field gradient of the triple electric quadrupole magnet assembly can be quickly adjusted, thereby quickly eliminating the star beam.

[0059] In another embodiment of this application, step 501, “calculating the star-shaped distortion degree of the initial beam shape compared with a standard uniform circular beam spot,” includes steps 601 to 602.

[0060] Step 601: Determine the number of first particles falling into the reference annular region in the initial beam shape.

[0061] In some embodiments, the reference annular region refers to an annular region formed from a preset ratio of beam spot radius to the beam spot radius. The preset ratio is ∈ (0,1). For example, the reference annular region may be an annular region formed from half the beam spot radius to the beam spot radius.

[0062] In some embodiments, the beam spot detection results may further include the number of particles at each location. The electronic device can determine the first number of particles based on the particle data at each location in the beam spot detection results.

[0063] Step 602: Determine the number of second particles falling into the reference fan-shaped region in the initial beam shape; the reference fan-shaped region is the fan-shaped region in the reference annular region from the first preset angle to the second preset angle.

[0064] In some embodiments, the reference sector region refers to a sector region within a reference annular region, extending from a first preset angle to a second preset angle. The first preset angle ∈ [0, 360], the second preset angle ∈ [0, 360], and the central angle of the reference sector region ∈ [0, 360]. For example, the first preset angle is 22.5°, and the second preset angle is 67.5°. The electronic device can determine the number of second particles from the received detection results.

[0065] Step 603: Calculate the star-shaped distortion degree based on the number of first particles, the number of second particles, the number of reference ring particles, and the number of reference sector particles; the number of reference ring particles is the number of particles of the standard uniform circular beam spot in the reference ring region; the number of reference sector particles is the number of particles of the standard uniform circular beam spot in the reference sector region.

[0066] In some embodiments, a first ratio of the number of second particles to the number of first particles can be calculated, and a second ratio of the number of reference fan-shaped particles to the number of reference ring-shaped particles can be calculated. Then, the star-shaped distortion degree is determined based on the first and second ratios. Specifically, the first and second ratios can be input into a preset monotonic function F(r). If the first ratio is r1 and the second ratio is r0, the star-shaped distortion degree can be |F(r1)-F(r0)|. It can be understood that a larger star-shaped distortion degree indicates a greater degree of star-shaped beam pattern.

[0067] The laser-accelerated star beam elimination method provided in this embodiment determines the number of first particles falling into the reference annular region and the number of second particles falling into the reference sector region in the initial beam shape, and calculates the star distortion degree based on the number of first particles, the number of second particles, the number of reference annular particles, and the number of reference sector particles. This allows for a more accurate evaluation of the star-shaped degree of the initial beam shape, and thus a more accurate determination of whether the initial beam shape has been distorted to form a star beam.

[0068] In one embodiment of this application, the preset ratio is 1 / 2, the first preset angle is 22.5°, the second preset angle is 67.5°, the first number of particles is n1, the second number of particles is n2, the reference ring particle number is m1, the reference fan particle number is m2, and 1 / (m2 / m1)=8. The star distortion degree is calculated based on the first particle number, the second particle number, the reference ring particle number, and the reference fan particle number, including: star distortion degree SL=[1 / (n2 / n1)-8] 2 .

[0069] In another embodiment of this application, step 103, "using preset beam dynamics simulation software to determine the target magnetic field gradient required to adjust the initial beam shape to the target beam shape", includes step 201.

[0070] Step 201: Input the target beam shape into the preset beam dynamics simulation software, and use the preset beam dynamics simulation software to calculate the target magnetic field gradient corresponding to the target beam shape; the target magnetic field gradient is the magnetic field gradient of the triple electric quadrupole magnet assembly.

[0071] In some embodiments, the target beam shape can be an ideal shape. For example, when a user wants to generate a circular spot with a diameter of 5 μm using a laser proton accelerator, the target beam shape is a circle with a diameter of 5 μm. When a user wants to generate an elliptical spot with a major axis of 10 μm and a minor axis of 5 μm using a laser proton accelerator, the target beam shape is an elliptical spot with a major axis of 10 μm and a minor axis of 5 μm.

[0072] In beam dynamics, there is a physical relationship between the magnetic field strength of the triple electric quadrupole magnet assembly and the beam at the target location, which is determined by the characteristics of the beam itself and the optical structure of the entire transmission line. Preset beam dynamics simulation software can simulate the beam transmission process by simulating this physical relationship and output various parameters and graphics, including the shape of the target beam.

[0073] In some embodiments, a beam transmission line model, such as the beam transmission line model of CLAPAⅠ or CLAPAⅡ, is established or imported into a preset beam dynamics simulation software. Then, the target beam shape is input into the preset beam dynamics simulation software, and the target magnetic field gradient that makes the beam shape at the target location the target beam shape is calculated by the preset beam dynamics simulation software.

[0074] For example, the beam transmission line model of CLAPAⅠ or CLAPAⅡ is imported into a preset beam dynamics simulation software; in the preset beam dynamics simulation software, the magnetic field gradient of the triple electric quadrupole magnet group is set as the independent variable, and the beam shape at the target location is set as the dependent variable; the optimizer or scanning function of the preset beam dynamics simulation software is used to generate a target function based on the physical relationship between the characteristics of the beam itself and the optical structure of the entire transmission line; the target function is iterated, the magnetic field gradient of the triple electric quadrupole magnet group is repeatedly adjusted and the value of the target function is calculated; the target magnetic field gradient that makes the beam shape at the target location the target beam shape is determined.

[0075] The laser-accelerated star beam elimination method provided in this embodiment inputs the target beam shape into a preset beam dynamics simulation software and uses the preset beam dynamics simulation software to calculate the target magnetic field gradient corresponding to the target beam shape. The preset beam dynamics simulation software can efficiently find the target magnetic field gradient that can achieve the target beam distribution in an iterative manner, thereby quickly achieving star beam elimination.

[0076] In another embodiment of this application, step 103, "using preset beam dynamics simulation software to determine the target magnetic field gradient required to adjust the initial beam shape to the target beam shape", includes steps 301 to 303.

[0077] Step 301: Input the initial beam distribution and its corresponding initial magnetic field gradient into the preset beam dynamics simulation software.

[0078] Step 302: Under the initial magnetic field gradient, if the initial beam distribution has a focal length greater than the focal length in the vertical direction than in the horizontal direction, then adjust the magnetic field gradient to increase the degree of over-focusing in the horizontal direction and the degree of under-focusing in the vertical direction until the initial beam shape changes to the target beam shape, and obtain the target magnetic field gradient.

[0079] Step 303: Under the initial magnetic field gradient, if the initial beam distribution has a focal length in the vertical direction that is less than that in the horizontal direction, then adjust the magnetic field gradient to increase the degree of over-focusing in the vertical direction and the degree of under-focusing in the horizontal direction until the initial beam shape changes to the target beam shape, and obtain the target magnetic field gradient.

[0080] The inventors discovered that when the focal points in the horizontal or vertical directions are positioned as close to each other as possible along the same longitudinal direction, the speed at which the focal point moves towards the beam transmission direction in the horizontal direction is not equal to that in the vertical direction under the same energy amplification. This causes under-focusing or over-focusing of different energy beams in the other direction, leading to the stacking of these beam envelopes of different energies to form a star-shaped beam. Therefore, this application eliminates the star-shaped beam by adjusting the initial beam distribution so that the focal length in the vertical direction is greater than the focal length in the horizontal direction, resulting in a more uniform laser acceleration beam.

[0081] In some embodiments, a preset beam dynamics simulation software is used to adjust the initial beam distribution so that the focal length in the vertical direction is less than the focal length in the horizontal direction. The horizontal focal length is reduced by increasing the degree of overfocusing in the horizontal direction and increased by increasing the degree of underfocusing in the horizontal direction. The vertical focal length is reduced by increasing the degree of overfocusing in the vertical direction and increased by increasing the degree of underfocusing in the vertical direction. This makes the vertical envelope of the initial beam distribution equal to the horizontal envelope. At this point, the initial beam shape can be adjusted to the target beam shape, and the magnetic field gradient at this point is the target magnetic field gradient.

[0082] The laser-accelerated star beam elimination method provided in this embodiment can quickly adjust the initial beam shape to the target beam shape by adjusting the focusing degree of the beam distribution in the vertical and horizontal directions, quickly determine the target magnetic field gradient, and thus quickly achieve star beam elimination.

[0083] In another embodiment of this application, step 104, "adjusting the magnetic field gradient of the triple electric quadrupole magnet assembly according to the target magnetic field gradient", includes steps 401 to 402.

[0084] Step 401: Calculate the target current intensity based on the magnet excitation formula of the triple electric quadrupole magnet assembly and the target magnetic field gradient.

[0085] Step 402: Set the current intensity of the three-pole electric quadrupole magnet group to the target current intensity so that the magnetic field gradient of the three-pole electric quadrupole magnet group is the target magnetic field gradient.

[0086] The laser-accelerated star beam elimination method provided in this application calculates the target current intensity based on the magnet excitation formula of the triple electric quadrupole magnet group and the target magnetic field gradient. This allows for rapid calculation of the target current, and the current intensity of the triple electric quadrupole magnet group is then set as the target current intensity, so that the magnetic field gradient of the triple electric quadrupole magnet group becomes the target magnetic field gradient, thereby enabling rapid star beam elimination.

[0087] In some embodiments, since electric quadrupole magnets generate a magnetic field using current, the target current intensity can be calculated based on the target magnetic field gradient. For example, the magnet excitation formula for a triple electric quadrupole magnet assembly can be I = G / K. Here, I is the target current intensity, typically in amperes (A); and G is the target magnetic field gradient, typically in tesla per meter (T / m) or tesla per meter. ¹, K is the gain constant or conversion constant of the magnet, with units of Tesla / meter / ampere (T / m / A) or (T / m ¹ / A), this constant is unique to each magnet and is provided by the manufacturer or obtained through measurement.

[0088] In some embodiments, the target drift distance refers to the distance in the beamline structure from the beam outlet of the triple quadrupole magnet assembly to the target location. Exemplarily, such as in CLAPAI or CLAPAII, it is the distance from the beam outlet of the triple quadrupole magnet assembly to the beam inlet of the beam shaping section.

[0089] The laser-accelerated star beam elimination method provided in this embodiment adjusts the target drift distance according to the initial beam shape to complete the star beam elimination process of the beam distribution and obtain the target beam distribution, which can quickly achieve laser-accelerated star beam elimination.

[0090] In yet another embodiment of this application, the laser-accelerated star beam elimination method further includes step 701.

[0091] Step 701: If it is determined that the initial beam shape distortion forms a star beam, and it is determined that the energy of the preset proton beam is greater than the energy threshold, then a target scatterer is set at the beam exit to perform star beam elimination processing on the initial beam distribution to obtain the target beam distribution; wherein, the thickness of the target scatterer is determined according to the energy of the preset proton beam.

[0092] In some embodiments, since the star-shaped beam is formed because the horizontal focal point moves at a greater speed towards the beam transmission direction than the vertical direction under the same energy amplification, and the scatterer has a slowing and scattering effect on the proton beam, the star-shaped beam elimination process of the initial beam distribution can be achieved by controlling the material and shape of the scatterer. Scattering leads to beam energy loss; therefore, when the preset proton beam energy is greater than an energy threshold, a target scatterer is placed at the beam outlet of the triple quadrupole magnet assembly to perform star-shaped beam elimination on the initial beam distribution. The thickness of the target scatterer is determined based on the preset proton beam energy. For example, the thickness of the target scatterer can be positively correlated with the preset proton beam energy.

[0093] The laser-accelerated star beam elimination method provided in this embodiment can quickly achieve star beam elimination processing of the initial beam distribution.

[0094] In one embodiment of this application, the target scatterer includes a lead scatterer and an organic scatterer; the organic scatterer has a first concave surface and a second concave surface arranged opposite to each other; the lead scatterer has a convex surface and a flat surface arranged opposite to each other; the convex surface fits into the second concave surface, and the smooth flat surface faces the beam outlet of the triple quadrupole magnet assembly.

[0095] In some embodiments, the slowing and stopping effect of the proton beam in the scatterer is caused by the Coulomb interaction between the protons and the electrons in the scatterer atoms, while the scattering effect is caused by the interaction between the protons and the atomic nuclei in the scatterer. Materials with low atomic numbers are more effective at slowing down protons, while materials with high atomic numbers can increase proton scattering. Therefore, a target scatterer is composed of lead scatterers and organic scatterers. The organic scatterer can be a polycarbonate scatterer.

[0096] In some embodiments, the target scatterer is positioned at the beam exit of a triple electric quadrupole magnet assembly, with the smooth surface of the lead scatterer facing the beam exit. The proton beam first enters the lead scatterer and is scattered. Due to the lead scatterer's spatial configuration (thicker in the middle and thinner at the edges), energy loss during proton beam scattering is reduced. Since the laser-accelerated proton beam has a high central energy, the proton beam does not lose much energy during scattering. Subsequently, the proton beam enters the organic scatterer. Because the organic scatterer has a spatial configuration (thinner in the middle and thicker at the edges), the energy spectrum distribution of the incident and emitted beams is approximately the same. Therefore, the energy spectrum distribution of the beam does not change significantly after passing through the organic scatterer.

[0097] The laser-accelerated star beam elimination method provided in this embodiment uses a target scatterer including a lead scatterer and an organic scatterer. The organic scatterer has a first concave surface and a second concave surface facing away from each other. The lead scatterer has a convex surface and a flat surface facing away from each other. The convex surface fits into the second concave surface, and the smooth flat surface faces the beam outlet of the triple quadrupole magnet assembly. This method can easily and quickly eliminate the star beam distribution of the initial beam, and ensures that the star beam elimination process does not affect the energy and energy spectrum distribution of the beam.

[0098] The effectiveness of the laser-accelerated star beam elimination method provided in this application will be introduced below through examples.

[0099] Figure 3 This is a schematic diagram of the initial beam shape in one example of this application. For example... Figure 3 As shown, the beam with a central energy of 100 MeV and an rms energy of 5 MeV exhibits a star-shaped distribution after passing through the triple quadrupole magnet assembly.

[0100] Figure 4 This is a schematic diagram of the target beam shape in one example of this application. For example... Figure 4 As shown, for Figure 3 The initial beam distribution presented in the simulation was used to determine the target current intensity required to adjust the initial beam shape to the target beam shape using pre-set beam dynamics simulation software. Based on the target current intensity, the current intensity of the triple quadrupole magnet assembly was adjusted to perform star-shaped beam elimination processing on the initial beam distribution. Figure 3After the initial beam distribution shown is processed by star beam elimination, the target beam shape no longer exhibits star-shaped distortion, and the target beam distribution becomes more uniform.

[0101] for Figure 3 and Figure 4 The beam shape shown above satisfies the above requirements. The star distortion degree is calculated using the preset star distortion degree formula distribution. Figure 3 The initial beam shape shown has a star-shaped distortion of 1189.6. Figure 4 The star-shaped distortion of the target beam shape shown is 0.067, indicating that the star-shaped distortion of the target beam distribution is significantly improved compared to the initial beam distribution.

[0102] Figure 5 This is a schematic diagram of the initial beam shape in one example of this application. For example... Figure 5 As shown, a proton beam with a central energy of 100 MeV and an rms energy of 5 MeV enters the CLAPAII beamline. From the time it enters the solenoid until it is homogenized, the beam distribution at the exit exhibits a star-shaped distribution.

[0103] Figure 6 This is a schematic diagram of the target beam shape in one example of this application. For example... Figure 6 As shown, for Figure 5 The initial beam distribution is presented in the image. A target scatterer and a square collimating aperture are set at the beam exit to perform star-shaped beam elimination processing on the initial beam distribution. Figure 5 After star-shaped beam elimination processing, the initial beam distribution shown no longer exhibits star-shaped distortion and is more uniformly distributed.

[0104] Figure 7 This is a schematic diagram of the structure of a target scatterer in one example of this application. Figure 7 As shown, the target scatterer includes lead scatterer 71 and organic scatterer 72.

[0105] Figure 8 This is a schematic diagram of a laser-accelerated star beam elimination device provided in another embodiment of this application. Figure 8 As shown, in another embodiment of this application, the laser-accelerated star beam elimination device 50 includes an acquisition module 51, a first determination module 52, a second determination module 53, and a processing module 54.

[0106] The acquisition module 51 is used to acquire the initial beam shape at the target location; the initial beam distribution is the preset beam distribution after the proton beam passes through the focusing section with a triple electric quadrupole magnet group.

[0107] The first determining module 52 is used to determine whether the initial beam shape is distorted to form a star-shaped beam.

[0108] The second determining module 53 is used to determine the target magnetic field gradient required to adjust the initial beam shape to the target beam shape if the initial beam shape distortion is determined to form a star beam.

[0109] Processing module 54 is used to adjust the magnetic field gradient of the triple quadrupole magnet group according to the target magnetic field gradient in order to eliminate the star beam and obtain the target beam distribution.

[0110] In another embodiment of this application, in order to quickly perform star-shaped beam elimination processing on the initial beam distribution, the second determining module is specifically used for: The target beam shape is input into the preset beam dynamics simulation software, and the target magnetic field gradient corresponding to the target beam shape is calculated using the preset beam dynamics simulation software; the target magnetic field gradient is the magnetic field gradient of the triple electric quadrupole magnet assembly.

[0111] In another embodiment of this application, in order to quickly perform star-shaped beam elimination processing on the initial beam distribution, the second determining module is specifically used for: Input the initial beam distribution and its corresponding initial magnetic field gradient into the preset beam dynamics simulation software; Under the initial magnetic field gradient, if the initial beam distribution has a focal length greater than the focal length in the vertical direction, the magnetic field gradient is adjusted to increase the degree of over-focusing in the horizontal direction and the degree of under-focusing in the vertical direction until the initial beam shape changes to the target beam shape, thus obtaining the target magnetic field gradient. Under the initial magnetic field gradient, if the initial beam distribution has a focal length in the vertical direction that is less than that in the horizontal direction, the magnetic field gradient is adjusted to increase the degree of over-focusing in the vertical direction and the degree of under-focusing in the horizontal direction until the initial beam shape changes to the target beam shape, thus obtaining the target magnetic field gradient.

[0112] In yet another embodiment of this application, in order to quickly achieve star-shaped beam elimination processing, the processing module is specifically used for: The target current intensity is calculated based on the magnet excitation formula of the triple electric quadrupole magnet assembly and the target magnetic field gradient. Set the current intensity of the triple electric quadrupole magnet assembly to the target current intensity so that the magnetic field gradient of the triple electric quadrupole magnet assembly becomes the target magnetic field gradient.

[0113] In yet another embodiment of this application, in order to quickly determine whether the initial beam shape has been distorted to form a star-shaped beam, the first determining module is specifically used for: Calculate the star-shaped distortion of the initial beam shape compared to a standard uniform circular beam spot; If the star-shaped distortion degree is greater than or equal to the preset distortion threshold, then the initial beam shape distortion is determined to form a star-shaped beam; If the star-shaped distortion degree is less than the preset distortion threshold, then the initial beam shape is determined to be undistorted and form a star-shaped beam.

[0114] In another embodiment of this application, in order to more accurately determine whether the initial beam shape is distorted to form a star-shaped beam, the first determining module is further configured to: Determine the number of the first particles falling into the reference annular region in the initial beam shape; Determine the number of second particles falling into the reference fan-shaped region in the initial beam shape; the reference fan-shaped region is the fan-shaped region in the reference annular region from the first preset angle to the second preset angle; The star-shaped distortion degree is calculated based on the number of first particles, the number of second particles, the number of reference ring particles, and the number of reference sector particles; the number of reference ring particles is the number of particles in the reference ring region of the standard uniform circular beam spot; the number of reference sector particles is the number of particles in the reference sector region of the standard uniform circular beam spot.

[0115] In another embodiment of this application, in order to quickly achieve star-shaped beam elimination processing of the initial beam distribution, the laser-accelerated star-shaped beam elimination device further includes a setting module, which is used for: If it is determined that the initial beam shape distortion forms a star-shaped beam, and it is determined that the energy of the preset proton beam is greater than the energy threshold, then a target scatterer is set at the beam exit to perform star-shaped beam elimination processing on the initial beam distribution to obtain the target beam distribution; wherein, the thickness of the target scatterer is determined according to the energy of the preset proton beam.

[0116] In another embodiment of this application, in order to ensure that the star beam elimination process does not affect the beam energy and energy spectrum distribution, the target scatterer includes a lead scatterer and an organic scatterer; the organic scatterer has a first concave surface and a second concave surface arranged opposite to each other; the lead scatterer has a convex surface and a plane arranged opposite to each other; the convex surface fits into the second concave surface, and the plane surface faces the beam outlet of the triple quadrupole magnet assembly.

[0117] Figure 9 A schematic diagram of the hardware structure of an electronic device provided in another embodiment of this application is shown below. Figure 9 As shown, in another embodiment of this application, the electronic device may include a processor 61 and a memory 62 storing computer program instructions.

[0118] Specifically, the processor 61 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0119] Memory 62 may include mass storage for data or instructions. For example, and not limitingly, memory 62 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 62 may include removable or non-removable (or fixed) media. Where appropriate, memory 62 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 62 is non-volatile solid-state memory.

[0120] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the methods according to one aspect of this disclosure.

[0121] The processor 61 reads and executes computer program instructions stored in the memory 62 to implement any of the laser-accelerated star beam elimination methods in the above embodiments.

[0122] In one example, the electronic device may also include a communication interface 63 and a bus 64. Wherein, such as Figure 9 As shown, the processor 61, memory 62, and communication interface 63 are connected via bus 64 and communicate with each other.

[0123] Communication interface 63 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0124] Bus 64 includes hardware, software, or both, that couples components of an online data traffic metering device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 64 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnect is contemplated herein.

[0125] This electronic device can implement any of the laser-accelerated star beam elimination methods in the embodiments of this application.

[0126] Furthermore, in conjunction with the laser-accelerated star beam elimination method in the above embodiments, this application embodiment can provide a computer-readable storage medium for implementation. This computer-readable storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any one of the laser-accelerated star beam elimination methods in the above embodiments.

[0127] This application also provides a computer program product, including a computer program that, when executed, implements any of the laser-accelerated star beam elimination methods described in the above embodiments.

[0128] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0129] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0130] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0131] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0132] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for eliminating laser-accelerated star-shaped beams, characterized in that, include: Obtain the initial beam shape at the target location; The initial beam distribution is a preset beam distribution after the proton beam passes through the focusing section with a triple electric quadrupole magnet assembly; Determine whether the initial beam shape is distorted to form a star-shaped beam; If it is determined that the initial beam shape distortion forms a star-shaped beam, then the target magnetic field gradient required to adjust the initial beam shape to the target beam shape is determined using preset beam dynamics simulation software; The magnetic field gradient of the triple quadrupole magnet assembly is adjusted according to the target magnetic field gradient to eliminate the star-shaped beam and obtain the target beam distribution.

2. The method according to claim 1, characterized in that, The step of determining the target magnetic field gradient required to adjust the initial beam shape to the target beam shape using preset beam dynamics simulation software includes: The target beam shape is input into a preset beam dynamics simulation software, and the target magnetic field gradient corresponding to the target beam shape is calculated using the preset beam dynamics simulation software; the target magnetic field gradient is the magnetic field gradient of a triple electric quadrupole magnet assembly.

3. The method according to claim 1, characterized in that, The calculation of the target magnetic field gradient corresponding to the target beam shape using preset beam dynamics simulation software includes: Input the initial beam distribution and its corresponding initial magnetic field gradient into the preset beam dynamics simulation software; Under the initial magnetic field gradient, if the initial beam distribution has a focal length greater than the focal length in the vertical direction, the magnetic field gradient is adjusted to increase the degree of over-focusing in the horizontal direction and the degree of under-focusing in the vertical direction until the initial beam shape changes to the target beam shape, thereby obtaining the target magnetic field gradient. Under the initial magnetic field gradient, if the initial beam distribution has a focal length in the vertical direction that is less than that in the horizontal direction, the magnetic field gradient is adjusted to increase the degree of over-focusing in the vertical direction and the degree of under-focusing in the horizontal direction until the initial beam shape changes to the target beam shape, thereby obtaining the target magnetic field gradient.

4. The method according to claim 1, characterized in that, The step of adjusting the magnetic field gradient of the triple electric quadrupole magnet assembly according to the target magnetic field gradient includes: The target current intensity is calculated based on the magnet excitation formula of the triple electric quadrupole magnet assembly and the target magnetic field gradient. The current intensity of the triple electric quadrupole magnet assembly is set to the target current intensity so that the magnetic field gradient of the triple electric quadrupole magnet assembly is the target magnetic field gradient.

5. The method according to claim 1, characterized in that, Determining whether the initial beam shape is distorted to form a star-shaped beam includes: Calculate the star-shaped distortion of the initial beam shape compared to a standard uniform circular beam spot; If the star-shaped distortion degree is greater than or equal to the preset distortion threshold, then the initial beam shape distortion is determined to form a star-shaped beam; If the star-shaped distortion degree is less than the preset distortion threshold, then it is determined that the initial beam shape has not been distorted to form a star-shaped beam.

6. The method according to claim 4, characterized in that, The calculation of the star-shaped distortion of the initial beam shape compared to a standard uniform circular beam spot includes: Determine the number of the first particles falling into the reference annular region in the initial beam shape; Determine the number of second particles falling into the reference fan-shaped region in the initial beam shape; the reference fan-shaped region is the fan-shaped region in the reference annular region from a first preset angle to a second preset angle; The star-shaped distortion degree is calculated based on the first particle number, the second particle number, the reference ring particle number, and the reference fan-shaped particle number; the reference ring particle number is the number of particles of the standard uniform circular beam spot in the reference ring region; the reference fan-shaped particle number is the number of particles of the standard uniform circular beam spot in the reference fan region.

7. The method according to claim 1, characterized in that, The method further includes: If it is determined that the initial beam shape distortion forms a star-shaped beam, and it is determined that the energy of the preset proton beam is greater than an energy threshold, then a target scatterer is set at the beam exit to perform star-shaped beam elimination processing on the initial beam distribution to obtain a target beam distribution; wherein, the thickness of the target scatterer is determined according to the energy of the preset proton beam.

8. The method according to claim 7, characterized in that, The target scatterer includes a lead scatterer and an organic scatterer; the organic scatterer has a first concave surface and a second concave surface facing away from each other; the lead scatterer has a convex surface and a flat surface facing away from each other; the convex surface is in contact with the second concave surface, and the flat surface faces the beam outlet of the triple quadrupole magnet assembly.

9. A laser-accelerated star beam elimination device, characterized in that, include: The acquisition module is used to acquire the initial beam shape at the target location; The initial beam distribution is a preset beam distribution after the proton beam passes through the focusing section with a triple electric quadrupole magnet assembly; The first determining module is used to determine whether the initial beam shape is distorted to form a star-shaped beam; The second determining module is used to determine the target magnetic field gradient required to adjust the initial beam shape to the target beam shape if it is determined that the initial beam shape distortion forms a star beam. The processing module is used to adjust the magnetic field gradient of the triple electric quadrupole magnet group according to the target magnetic field gradient in order to eliminate the star beam and obtain the target beam distribution.

10. An electronic device, characterized in that, include: Processor and memory storing computer program instructions; When the processor executes the computer program instructions, it implements the method as described in any one of claims 1-8.

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