CN114885489B - Homogenization method for laser acceleration proton beam - Google Patents

Homogenization method for laser acceleration proton beam Download PDF

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CN114885489B
CN114885489B CN202210535020.3A CN202210535020A CN114885489B CN 114885489 B CN114885489 B CN 114885489B CN 202210535020 A CN202210535020 A CN 202210535020A CN 114885489 B CN114885489 B CN 114885489B
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magnet
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CN114885489A (en
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王科栋
朱昆
王凯
颜学庆
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Guangdong Xinxing Laser Plasma Technology Research Institute
Peking University
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Peking University
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
    • H05H7/001—Arrangements for beam delivery or irradiation
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    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1077—Beam delivery systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1085—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy characterised by the type of particles applied to the patient
    • A61N2005/1087—Ions; Protons
    • A61N2005/1088—Ions; Protons generated by laser radiation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E30/10—Nuclear fusion reactors

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Abstract

The invention discloses a homogenizing method of laser acceleration proton beam. The invention adopts the flat magnetic field transposed quadrupole magnet and the high-order magnet, and realizes the uniform distribution of proton beam current by setting the focusing strength of the flat magnetic field transposed quadrupole magnet and the high-order magnet and the distance between the focusing strength and the beam current drifting section; the invention abandons the control method of using continuous scanning superposition dose of the traditional cancer treatment accelerator, optimizes the original Gaussian distribution beam group into a rectangle with relatively regular particle distribution, and the application of the rectangular beam spot ensures that the irradiation area of scanning superposition covers the focus and has no superposition; the laser-generated particles can be maximally utilized and converted into rectangular beam which is easier to control, so that step scanning can be conveniently performed in the treatment process, and the irradiated focus can be ensured to receive uniform and controllable dose irradiation; the invention adopts the high-order magnet to finish the optimization of the uniformity of the laser-driven proton beam, and advances the project of the laser-driven proton treatment device.

Description

Homogenization method for laser acceleration proton beam
Technical Field
The invention relates to a laser proton accelerator, in particular to a homogenizing method of laser acceleration proton beam.
Background
The traditional X-ray and other photon radiotherapy has large side effect and poor effect, and the recurrence rate is high. The proton and heavy ion have Bragg peak, so that the ion has great advantage in radiation treatment of human body, and can not release a large amount of energy immediately after entering the human body, and only release most of energy at the position where the ion stops, thereby effectively killing deep tumor and simultaneously minimizing damage to shallow normal tissue. Proton and heavy ion tumor treatment has been over 154000 cases worldwide by 2015, with proton treatment cases exceeding 130000. However, the ion accelerating equipment using the radio frequency accelerator as the main body has large volume, high manufacturing cost, and difficult maintenance and operation cost and is not easy to popularize.
The laser driven proton treatment equipment is a novel proton accelerator which is being designed by Beijing university, is the first laser driven proton accelerator in the world, protons are generated by laser-plasma interaction, and the energy of the protons reaches 100MeV by using 2PW laser. The laser accelerator using the new principle can accelerate the gradient to more than 100GV/m (at least 3 orders of magnitude higher than the radio frequency accelerator), can reduce the size and cost of the accelerator significantly. Super-short laser driven accelerators have become one of the most attractive topics for the accelerator community in recent years due to their high acceleration gradients.
The beam intensity generated by the traditional proton cancer treatment accelerator is stronger, so that the area of the beam passing through is controlled by using a scatterer to further control the irradiation dose of a focus, or the irradiation area is scanned by superposing scanning iron, and the dose of the irradiated focus is controlled by treatment planning software. The beam transport system adjusts the size of a particle beam by using a quadrupole magnet or the like in the system, and transports the particle beam to a target position called an isocenter in a treatment room, and the radiation dose distribution is a scatterer irradiation method in which a beam shape is conformed to an affected part shape by making the beam strike the scatterer, and a scanning irradiation method in which a fine beam is scanned by using an electromagnet called a scanning electromagnet in combination with the affected part shape.
But the flow leveling intensity of the proton beam driven by the laser is lower, and the beam shape can be controlled in a pre-homogenization mode.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a homogenizing method for accelerating proton beam by laser.
The invention relates to a homogenizing method of laser acceleration proton beam, which comprises the following steps:
1) Setting a laser acceleration proton beam homogenization system:
A beam collecting section, an energy selecting section, a beam homogenizing transmission line and a beam shaping transmission line are sequentially arranged along the beam transmission direction; the beam current generated by laser targeting passes through a beam current collecting section and an energy selecting section to obtain proton beam current with ideal energy; the transverse distribution of the proton beam with ideal energy is Gaussian distribution, ideal energy particles pass through a beam homogenization transmission line to finish the operation of beam uniform distribution, and finally the uniform proton beam with rectangular cross section is obtained through the beam homogenization transmission line; the proton beam after passing through the beam collecting section and the energy expanding and selecting section enters a beam homogenizing transmission line and moves along the Z direction; the proton beam transmitted to the beam homogenization transport line is circular beam distributed in Gaussian in the XOY plane, and the center of the beam is synchronous particle, namely particle moving in ideal state;
A first X-direction flat magnetic field transposition quadrupole magnet, a second X-direction flat magnetic field transposition quadrupole magnet, a first high-order magnet, a first Y-direction flat magnetic field transposition quadrupole magnet, a second Y-direction flat magnetic field transposition quadrupole magnet and a second high-order magnet are sequentially arranged in the beam homogenization transmission line; the magnetic fields generated by the first and second X-direction flat magnetic field transposed quadrupole magnets defocus the proton beam in the X direction and focus the proton beam in the Y direction; the placement distance between the second X-direction flat magnetic field transposed quadrupole magnet and the first quadrupole magnet is as short as possible, and only the installation position is reserved; a distance is reserved between the first high-order magnet and the second X-direction flat magnetic field transposed quadrupole magnet; the magnetic fields generated by the first and second Y-direction flat magnetic field transposed quadrupole magnets defocus the proton beam in the Y direction and focus the proton beam in the X direction; the placement distance between the second Y-direction flat magnetic field transposed quadrupole magnet and the second Y-direction flat magnetic field transposed quadrupole magnet is as short as possible, and only the installation position is reserved; a distance is reserved between the second high-order magnet and the second Y-direction flat magnetic field transposed quadrupole magnet; the distance between the installation centers of the first X-direction flat magnetic field transposition quadrupole magnet and the second X-direction flat magnetic field transposition quadrupole magnet is a first beam drift section, the distance between the second X-direction flat magnetic field transposition quadrupole magnet and the first high-order magnet is a second beam drift section, the distance between the first high-order magnet and the first Y-direction flat magnetic field transposition quadrupole magnet is a third beam drift section, the distance between the first Y-direction flat magnetic field transposition quadrupole magnet and the installation centers of the second Y-direction flat magnetic field transposition quadrupole magnet is a fourth beam drift section, and the distance between the second Y-direction flat magnetic field transposition quadrupole magnet and the second high-order magnet is a fifth beam drift section;
2) The motion state of the beam before entering the beam homogenization transmission line is as follows:
Wherein, R x0、x0 and X' 0 are respectively the motion state matrix, the position and the momentum in the X direction before entering the beam homogenization transmission line; r y0、y0 and Y' 0 are the motion state matrix, position and momentum in the Y direction before entering the beam homogenization transmission line respectively; r z0、z0 and Z' 0 are the motion state matrix, position and momentum in the Z direction before entering the beam homogenization transmission line, respectively;
3) Proton beam current taking synchronous particles as the center passes through the magnetic center of the first X-direction flat magnetic field transposed quadrupole magnet along the Z-axis direction, the proton beam current is compressed along the Y-direction while being stretched along the X-direction under the action of a magnetic field, the stretching degree of the X-direction is respectively in direct proportion to the strength and the drift distance of the magnetic field, the strength of the magnetic field is in direct proportion to the applied current, the stretching size is increased along with the increase of the drift distance of the proton beam current and the increase of the magnet current, and the motion state of the beam current after passing through the first X-direction flat magnetic field transposed quadrupole magnet is as follows:
wherein, R x1、Ry1 and R z1 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the first X direction flat magnetic field, And/>The transmission matrix in the X direction, the Y direction and the Z direction passing through the first X-direction flat magnetic field transposed quadrupole magnet are respectively f x1 and f y1, the focusing intensities in the X direction and the Y direction of the first X-direction flat magnetic field transposed quadrupole magnet are respectively X 1、y1 and Z 1, the positions in the X direction, the Y direction and the Z direction passing through the first X-direction flat magnetic field transposed quadrupole magnet are respectively X 1、y′1 and Z' 1
Momentum in the X direction, the Y direction and the Z direction of the quadrupole magnets are transposed by the first X-direction flat magnetic field respectively;
4) The proton beam enters the second X-direction flat magnetic field transposition quadrupole magnet through the first beam drift section after passing through the first X-direction flat magnetic field transposition quadrupole magnet, and the movement state before the beam enters the second X-direction flat magnetic field transposition quadrupole magnet through the first beam drift section is as follows:
Wherein, R x2、Ry2 and R z2 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the first beam drift section, R xx1、Ryy1 and R zz1 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the first beam drift section, X 2、y2 and Z 2 are positions in the X direction, the Y direction and the Z direction after passing through the first beam drift section, X '2、y′2 and Z' 2 are momentums in the X direction, the Y direction and the Z direction after passing through the first beam drift section, Δs 1 is a distance of the first beam drift section, and γ is a relative velocity of beams;
5) The beam flow enters the second X-direction flat magnetic field transposition quadrupole magnet after passing through the first beam flow drift section, the synchronous particles pass through the magnetic center of the second X-direction flat magnetic field transposition quadrupole magnet, the proton beam flow is compressed along the Y direction while continuously stretching along the X direction under the action of the magnetic field, the proton beam flow is stretched along the X direction and compressed along the Y direction by passing through the first and the second X-direction flat magnetic field transposition quadrupole magnets, the X direction of the proton beam flow has flattening trend, and the movement state of the beam flow after passing through the second X-direction flat magnetic field transposition quadrupole magnet is as follows:
Wherein, R x3、Ry3 and R z3 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the second X direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transposed quadrupole magnet are respectively shown, f x2 and f y2 are respectively shown as the focusing intensities along the X direction and the Y direction of the second X-direction flat magnetic field transposed quadrupole magnet, X 3、y3 and Z 3 are respectively shown as the positions along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transposed quadrupole magnet, and X '3、y′3 and Z' 3 are respectively shown as the momentums along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transposed quadrupole magnet;
6) After the proton beam comes out of the second X-direction flat magnetic field transposed quadrupole magnet, the proton beam drifts through a second beam drift section, the transverse-longitudinal ratio of the proton beam gradually becomes larger in the drifting process, and the motion state of the proton beam before entering the first high-order magnet through the second beam drift section is as follows:
Wherein, R x4、Ry4 and R z4 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the second beam drift section, R xx2、Ryy2 and R zz2 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the second beam drift section, X 4、y4 and Z 4 are positions in the X direction, the Y direction and the Z direction after passing through the second beam drift section, X '4、y′4 and Z' 4 are momentums in the X direction, the Y direction and the Z direction after passing through the second beam drift section, and Δs 2 is a distance of the second beam drift section;
7) When the proton beam drifts to the transverse-longitudinal ratio of more than or equal to 4:1, the proton beam passes through the magnetic center of the first high-order magnet; the magnetic field generated by the first high-order magnet is linearly and slowly changed along the X direction when approaching to the magnetic center, and is rapidly increased when being far away from the magnetic center, so that the proton beam current in the X direction far from the magnetic center is subjected to larger magnetic field force to further lead to filamentization and gradually approaches to synchronous particles in the center; the motion state of the beam flow before passing through the first high-order magnet is as follows:
Wherein, R x5、Ry5 and R z5 are respectively motion state matrixes of X direction, Y direction and Z direction after passing through the first high-order magnet, And/>The transmission matrix is respectively a transmission matrix passing through the first high-order magnet along the X direction, the Y direction and the Z direction, f x3 and f y3 are respectively the focusing intensities of the first high-order magnet along the X direction and the Y direction, X 5、y5 and Z 5 are respectively the positions passing through the first high-order magnet along the X direction, the Y direction and the Z direction, and X '5、y′5 and Z' 5 are respectively the momentums passing through the first high-order magnet along the X direction, the Y direction and the Z direction;
8) After the proton beam passes through the first high-order magnet, the proton beam drifts through a third beam drift section, in the drifting process, particles far away from the center of the proton beam are subjected to stronger force to move towards the center, so that the proton beam originally in Gaussian distribution is gradually and uniformly distributed along the X direction, and the movement state of the beam before entering the first Y-direction flat magnetic field transposed quadrupole magnet through the third beam drift section is as follows:
Wherein, R x6、Ry6 and R z6 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the third beam drift section, R xx3、Ryy3 and R zz3 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the third beam drift section, X 6、y6 and Z 6 are positions in the X direction, the Y direction and the Z direction after passing through the third beam drift section, X '6、y′6 and Z' 6 are momentums in the X direction, the Y direction and the Z direction after passing through the third beam drift section, and Δs 3 is a distance of the third beam drift section;
9) Proton beam flows which are uniformly distributed along the X direction enter a first Y-direction flat magnetic field transposed quadrupole magnet to be decoupled in the Y direction; synchronous particles pass through the magnetic center of the first Y-direction flat magnetic field transposed quadrupole magnet, proton beam current is compressed along the X direction while being stretched along the Y direction under the action of a magnetic field, the stretching degree of the Y direction is respectively in direct proportion to the strength and the drift distance of the magnetic field, the stretching size is increased along with the increase of the drift distance of the proton beam current and the increase of the magnet current, and the movement state of the beam current after passing through the first Y-direction flat magnetic field transposed quadrupole magnet is as follows:
wherein, R x7、Ry7 and R z7 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the first Y direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the four-pole magnet are respectively transferred through the first Y-direction flat magnetic field, f x4 and f y4 are respectively the focusing intensities along the X direction and the Y direction of the four-pole magnet, X 7、y7 and Z 7 are respectively the positions along the X direction, the Y direction and the Z direction of the four-pole magnet through the first Y-direction flat magnetic field, and X '7、y′7 and Z' 7 are respectively the momentums along the X direction, the Y direction and the Z direction of the four-pole magnet through the first Y-direction flat magnetic field;
10 The proton beam enters the second Y-direction flat magnetic field transposed quadrupole magnet through the fourth beam drift section after passing through the first Y-direction flat magnetic field transposed quadrupole magnet, and the motion state before the beam enters the second Y-direction flat magnetic field transposed quadrupole magnet through the fourth beam drift section is as follows:
Wherein, R x8、Ry8 and R z8 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, R xx4、Ryy4 and R zz4 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, X 8、y8 and Z 8 are positions in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, X '8、y′8 and Z' 8 are momentums in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, and Δs 4 is a distance of the fourth beam drift section;
11 Synchronous particles pass through the magnetic center of the second Y-direction flat magnetic field transposed quadrupole magnet, the proton beam is compressed along the X direction while being stretched along the Y direction under the action of the magnetic field, the proton beam is stretched along the Y direction and compressed along the X direction by the first and second Y-direction flat magnetic field transposed quadrupole magnets, the Y direction of the proton beam has flattening trend, and the movement state of the beam after passing through the second Y-direction flat magnetic field transposed quadrupole magnet is as follows:
Wherein, R x9、Ry9 and R z9 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the second Y direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the quadrupole magnet are transferred through the second Y-direction flat magnetic field transposition, f x5 and f y5 are the focusing intensities along the X direction and the Y direction of the quadrupole magnet are transferred through the second Y-direction flat magnetic field transposition, X 9、y9 and Z 9 are the positions along the X direction, the Y direction and the Z direction of the quadrupole magnet are transferred through the second Y-direction flat magnetic field transposition, and X '9、y′9 and Z' 9 are the momentums along the X direction, the Y direction and the Z direction of the quadrupole magnet are transferred through the second Y-direction flat magnetic field transposition;
12 After the proton beam flows out of the second Y-direction flat magnetic field transposed quadrupole magnet and drifts through a fifth beam drift section, the transverse-longitudinal ratio of the proton beam gradually becomes smaller in the drifting process, and the movement state of the proton beam before entering the second high-order magnet through the fifth beam drift section is as follows:
Wherein, R x10、Ry10 and R z10 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, R xx5、Ryy5 and R zz5 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, X 10、y10 and Z 10 are positions in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, X '10、y′10 and Z' 10 are momentums in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, and Δs 5 is a distance of the fifth beam drift section;
13 When the proton beam drifts to the transverse-longitudinal ratio of less than or equal to 1:4, the proton beam passes through the magnetic center of the second section of high-order magnet; the magnetic field generated by the second high-order magnet is linearly and slowly changed when approaching to the magnetic center along the Y direction and rapidly increased when being away from the magnetic center, so that the proton beam current in the Y direction away from the magnetic center is subjected to larger magnetic field force to lead to filarization and gradually approaches to synchronous particles in the center; after passing through the second high-order magnet, the proton beam drifts, and in the drifting process, particles far away from the center of the proton beam are subjected to stronger force to move towards the center, so that the original Gaussian-distributed proton beam is gradually and uniformly distributed along the Y direction, and the motion state of the second-section high-order magnet after the beam passes through is as follows:
wherein, R x、Ry and R z are respectively motion state matrixes of X direction, Y direction and Z direction after passing through the second high-order magnet, And/>The transmission matrix is respectively a transmission matrix passing through the second high-order magnet along the X direction, the Y direction and the Z direction, f x6 and f y6 are respectively the focusing intensities of the second high-order magnet along the X direction and the Y direction, X, Y and Z are respectively the positions passing through the second high-order magnet along the X direction, the Y direction and the Z direction, and X ', Y ' and Z ' are respectively the momentums passing through the second high-order magnet along the X direction, the Y direction and the Z direction;
By setting the focusing intensities f x1 and f y1 of the first X-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, respectively, the focusing intensities f x2 and f y2 of the second X-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, the focusing intensities f x3 and f y3 of the first high-order magnet in the X-direction and the Y-direction, the focusing intensities f x4 and f y4 of the first Y-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, the focusing intensities f x5 and f y5 of the second Y-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, focusing intensities f x6 and f y6 of the second high-order magnet in the X direction and the Y direction, a distance Deltas 1 of the first beam drift section, a distance Deltas 2 of the second beam drift section, a distance Deltas 3 of the third beam drift section, a distance Deltas 4 of the fourth beam drift section and a distance Deltas 5 of the fifth beam drift section, so that beams in the X direction and the Y direction are homogenized,
The cross section of the proton beam passing through the second high-order magnet is gradually changed into a rectangular beam which is uniformly distributed.
Wherein, the beam current collection section includes: three superconducting solenoids connected in sequence, each solenoid is connected by a vacuum pipeline, and a beam diagnosis element is arranged in the vacuum pipeline.
The energy selection section includes: the first and second quadrupole magnets, the first horizontal 45-degree deflection magnet, the third and fourth quadrupole magnets and the second horizontal 45-degree deflection magnet are sequentially connected.
The beam shaping transmission line includes: the three quadrupolar magnets are sequentially connected, and adjacent quadrupolar magnets are connected through vacuum pipelines.
The first and second higher order magnets are octapole magnets.
The invention has the advantages that:
The invention abandons the control method of using continuous scanning superposition dose of the traditional cancer treatment accelerator, optimizes the original Gaussian distribution beam group into a rectangle with relatively regular particle distribution, and the application of the rectangular beam spot ensures that the irradiation area of scanning superposition covers the focus and has no superposition; by the mode, the particles generated by laser can be converted into rectangular beam which is easier to control, so that step scanning is conveniently performed in the treatment process, and the irradiated focus can be ensured to receive uniform and controllable dose irradiation; the invention adopts the high-order magnet to finish the optimization of the uniformity of the laser-driven proton beam, and advances the project of the laser-driven proton treatment device.
Drawings
FIG. 1 is a schematic diagram of one embodiment of a laser-accelerated proton beam homogenization system employed in the present invention;
FIG. 2 is a beam profile variation of an XY-direction cross section obtained by one embodiment of a method for homogenizing a laser-accelerated proton beam in accordance with the present invention;
FIG. 3 is a beam homogenization process diagram of one embodiment of a homogenization method of a laser-accelerated proton beam in accordance with the present invention;
FIG. 4 is a diagram illustrating a comparison of beam homogenization and non-homogenization obtained by one embodiment of a homogenization method for a laser-accelerated proton beam in accordance with the present invention;
FIG. 5 is a schematic diagram of one embodiment of a quadrupole magnet employed in the present invention;
Fig. 6 is a schematic diagram of one embodiment of an octapole magnet employed in the present invention.
Detailed Description
The invention will be further elucidated by means of specific embodiments in conjunction with the accompanying drawings.
As shown in fig. 1, the laser-accelerated proton beam homogenization system employed in the present embodiment includes: a beam collecting section 8, an energy selecting section 9, a beam homogenizing transmission line 7 and a beam shaping transmission line 10; the beam current generated by laser targeting passes through a beam current collecting section and an energy selecting section to obtain proton beam current with ideal energy; the transverse distribution of the proton beam with ideal energy is Gaussian distribution, the ideal energy particles finish the operation of uniform distribution of the beam in a beam homogenization transmission line, and finally the uniform proton beam with rectangular cross section is obtained through the beam homogenization transmission line and is used for treating cancers by later step scanning; the proton beam after passing through the beam collecting section and the energy expanding and selecting section enters a beam homogenizing transmission line and moves along the Z direction; the proton beam transmitted to the beam homogenization transport line is circular beam distributed in Gaussian in the XOY plane, and the center of the beam is synchronous particle, namely particle moving in ideal state;
the beam homogenization transmission line includes: a first X-direction flat magnetic field transposed quadrupole magnet 1, a second X-direction flat magnetic field transposed quadrupole magnet 2, a first higher order magnet 3, a first Y-direction flat magnetic field transposed quadrupole magnet 4, a second Y-direction flat magnetic field transposed quadrupole magnet 5, and a second higher order magnet 6; the magnetic fields generated by the first and second X-direction flat magnetic field transposed quadrupole magnets defocus the proton beam in the X direction and focus the proton beam in the Y direction; the arrangement distance between the second X-direction flat magnetic field transposed quadrupole magnet and the first quadrupole magnet is as short as possible, and only the installation position is reserved; a distance is reserved between the first high-order magnet and the second X-direction flat magnetic field transposed quadrupole magnet; the magnetic fields generated by the first and second Y-direction flat magnetic field transposed quadrupole magnets defocus the proton beam in the Y direction and focus the proton beam in the X direction; the arrangement distance between the second Y-direction flat magnetic field transposed quadrupole magnet and the second Y-direction flat magnetic field transposed quadrupole magnet is as short as possible, and only the installation position is reserved; the second high-order magnet is separated from the second Y-direction flat magnetic field transposed quadrupole magnet.
The homogenizing method of the laser acceleration proton beam of the present embodiment, as shown in fig. 2 and 3, includes the following steps:
1) Setting a laser acceleration proton beam homogenization system as shown in fig. 1;
The distance between the installation centers of the first X-direction flat magnetic field transposition quadrupole magnet and the second X-direction flat magnetic field transposition quadrupole magnet is a first beam drift section, the distance between the second X-direction flat magnetic field transposition quadrupole magnet and the first high-order magnet is a second beam drift section, the distance between the first high-order magnet and the first Y-direction flat magnetic field transposition quadrupole magnet is a third beam drift section, the distance between the first Y-direction flat magnetic field transposition quadrupole magnet and the installation centers of the second Y-direction flat magnetic field transposition quadrupole magnet is a fourth beam drift section, and the distance between the second Y-direction flat magnetic field transposition quadrupole magnet and the second high-order magnet is a fifth beam drift section;
2) The motion state of the beam before entering the beam homogenization transmission line is as follows:
Wherein, R x0、x0 and X' 0 are respectively the motion state matrix, the position and the momentum in the X direction before entering the beam homogenization transmission line; r y0、y0 and Y' 0 are the motion state matrix, position and momentum in the Y direction before entering the beam homogenization transmission line respectively; r z0、z0 and Z' 0 are the motion state matrix, position and momentum in the Z direction before entering the beam homogenization transmission line, respectively;
3) Proton beam current taking synchronous particles as the center passes through the magnetic center of the first X-direction flat magnetic field transposed quadrupole magnet along the Z-axis direction, the proton beam current is compressed along the Y-direction while being stretched along the X-direction under the action of a magnetic field, the stretching degree of the X-direction is respectively in direct proportion to the strength and the drift distance of the magnetic field, the strength of the magnetic field is in direct proportion to the applied current, the stretching size is increased along with the increase of the drift distance of the proton beam current and the increase of the magnet current, and the motion state of the beam current after passing through the first X-direction flat magnetic field transposed quadrupole magnet is as follows:
wherein, R x1、Ry1 and R z1 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the first X direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the four-pole magnet are respectively transmitted through the first X-direction flat magnetic field transposition, f x1 and f y1 are respectively the focusing intensities along the X direction and the Y direction of the four-pole magnet, X 1、y1 and Z 1 are respectively the positions along the X direction, the Y direction and the Z direction of the four-pole magnet through the first X-direction flat magnetic field transposition, and X '1、y′1 and Z' 1 are respectively the momentums along the X direction, the Y direction and the Z direction of the four-pole magnet through the first X-direction flat magnetic field transposition;
4) The proton beam enters the second X-direction flat magnetic field transposition quadrupole magnet through the first beam drift section after passing through the first X-direction flat magnetic field transposition quadrupole magnet, and the movement state before the beam enters the second X-direction flat magnetic field transposition quadrupole magnet through the first beam drift section is as follows:
Wherein, R x2、Ry2 and R z2 are motion state matrixes of X direction, Y direction and Z direction after passing through the first beam drift section, R xx1、Ryy1 and R zz1 are transmission matrixes of X direction, Y direction and Z direction after passing through the first beam drift section, X 2、y2 and Z 2 are positions of X direction, Y direction and Z direction after passing through the first beam drift section, X '2、y′2 and Z' 2 are momentum of X direction, Y direction and Z direction after passing through the first beam drift section, Δs 1 is distance of the first beam drift section, γ is relative speed of beam, the effect of magnetic field does not influence speed, and γ is a constant value;
5) The beam flow enters the second X-direction flat magnetic field transposition quadrupole magnet after passing through the first beam flow drift section, the synchronous particles pass through the magnetic center of the second X-direction flat magnetic field transposition quadrupole magnet, the proton beam flow is compressed along the Y direction while continuously stretching along the X direction under the action of the magnetic field, the proton beam flow is stretched along the X direction and compressed along the Y direction by passing through the first and the second X-direction flat magnetic field transposition quadrupole magnets, the X direction of the proton beam flow has flattening trend, and the movement state of the beam flow after passing through the second X-direction flat magnetic field transposition quadrupole magnet is as follows:
Wherein, R x3、Ry3 and R z3 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the second X direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transposed quadrupole magnet are respectively shown, f x2 and f y2 are respectively shown as the focusing intensities along the X direction and the Y direction of the second X-direction flat magnetic field transposed quadrupole magnet, X 3、y3 and Z 3 are respectively shown as the positions along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transposed quadrupole magnet, and X '3、y′3 and Z' 3 are respectively shown as the momentums along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transposed quadrupole magnet; in practical application, as one quadrupole magnet cannot generate magnetic field gradient meeting the requirement, two sets of quadrupole magnets which can also play a role in flattening the beam X direction are adopted for design calculation, and the two sets of quadrupole magnets are taken as a whole for overall consideration in the early-stage parameter optimization;
6) After the proton beam comes out of the second X-direction flat magnetic field transposed quadrupole magnet, the proton beam drifts through a second beam drift section, the transverse-longitudinal ratio of the proton beam gradually becomes larger in the drifting process, and the motion state of the proton beam before entering the first high-order magnet through the second beam drift section is as follows:
Wherein, R x4、Ry4 and R z4 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the second beam drift section, R xx2、Ryy2 and R zz2 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the second beam drift section, X 4、y4 and Z 4 are positions in the X direction, the Y direction and the Z direction after passing through the second beam drift section, X '4、y′4 and Z' 4 are momentums in the X direction, the Y direction and the Z direction after passing through the second beam drift section, and Δs 2 is a distance of the second beam drift section;
7) When the proton beam drifts to the transverse-longitudinal ratio of more than or equal to 4:1, the proton beam passes through the magnetic center of the first high-order magnet; the magnetic field generated by the first high-order magnet is linearly and slowly changed along the X direction when approaching to the magnetic center, and is rapidly increased when being far away from the magnetic center, so that the proton beam current in the X direction far from the magnetic center is subjected to larger magnetic field force to further lead to filamentization and gradually approaches to synchronous particles in the center; the motion state of the beam flow before passing through the first high-order magnet is as follows:
Wherein, R x5、Ry5 and R z5 are respectively motion state matrixes of X direction, Y direction and Z direction after passing through the first high-order magnet, And/>The transmission matrix is respectively a transmission matrix passing through the first high-order magnet along the X direction, the Y direction and the Z direction, f x3 and f y3 are respectively the focusing intensities of the first high-order magnet along the X direction and the Y direction, X 5、y5 and Z 5 are respectively the positions passing through the first high-order magnet along the X direction, the Y direction and the Z direction, and X '5、y′5 and Z' 5 are respectively the momentums passing through the first high-order magnet along the X direction, the Y direction and the Z direction;
8) After the proton beam passes through the first high-order magnet, the proton beam drifts through a third beam drift section, in the drifting process, particles far away from the center of the proton beam are subjected to stronger force to move towards the center, so that the proton beam originally in Gaussian distribution is gradually and uniformly distributed along the X direction, and the movement state of the beam before entering the first Y-direction flat magnetic field transposed quadrupole magnet through the third beam drift section is as follows:
Wherein, R x6、Ry6 and R z6 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the third beam drift section, R xx3、Ryy3 and R zz3 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the third beam drift section, X 6、y6 and Z 6 are positions in the X direction, the Y direction and the Z direction after passing through the third beam drift section, X '6、y′6 and Z' 6 are momentums in the X direction, the Y direction and the Z direction after passing through the third beam drift section, and Δs 3 is a distance of the third beam drift section;
9) Proton beam flows which are uniformly distributed along the X direction enter a first Y-direction flat magnetic field transposed quadrupole magnet to be decoupled in the Y direction; synchronous particles pass through the magnetic center of the first Y-direction flat magnetic field transposed quadrupole magnet, proton beam current is compressed along the X direction while being stretched along the Y direction under the action of a magnetic field, the stretching degree of the Y direction is respectively in direct proportion to the strength and the drift distance of the magnetic field, the stretching size is increased along with the increase of the drift distance of the proton beam current and the increase of the magnet current, and the movement state of the beam current after passing through the first Y-direction flat magnetic field transposed quadrupole magnet is as follows:
/>
wherein, R x7、Ry7 and R z7 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the first Y direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the four-pole magnet are respectively transferred through the first Y-direction flat magnetic field, f x4 and f y4 are respectively the focusing intensities along the X direction and the Y direction of the four-pole magnet, X 7、y7 and Z 7 are respectively the positions along the X direction, the Y direction and the Z direction of the four-pole magnet through the first Y-direction flat magnetic field, and X '7、y′7 and Z' 7 are respectively the momentums along the X direction, the Y direction and the Z direction of the four-pole magnet through the first Y-direction flat magnetic field;
10 The proton beam enters the second Y-direction flat magnetic field transposed quadrupole magnet through the fourth beam drift section after passing through the first Y-direction flat magnetic field transposed quadrupole magnet, and the motion state before the beam enters the second Y-direction flat magnetic field transposed quadrupole magnet through the fourth beam drift section is as follows:
Wherein, R x8、Ry8 and R z8 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, R xx4、Ryy4 and R zz4 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, X 8、y8 and Z 8 are positions in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, X '8、y′8 and Z' 8 are momentums in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, and Δs 4 is a distance of the fourth beam drift section;
11 Synchronous particles pass through the magnetic center of the second Y-direction flat magnetic field transposed quadrupole magnet, the proton beam is compressed along the X direction while being stretched along the Y direction under the action of the magnetic field, the proton beam is stretched along the Y direction and compressed along the X direction by the first and second Y-direction flat magnetic field transposed quadrupole magnets, the Y direction of the proton beam has flattening trend, and the movement state of the beam after passing through the second Y-direction flat magnetic field transposed quadrupole magnet is as follows:
Wherein, R x9、Ry9 and R z9 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the second Y direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the quadrupole magnet are transferred through the second Y-direction flat magnetic field transposition, f x5 and f y5 are the focusing intensities along the X direction and the Y direction of the quadrupole magnet are transferred through the second Y-direction flat magnetic field transposition, X 9、y9 and Z 9 are the positions along the X direction, the Y direction and the Z direction of the quadrupole magnet are transferred through the second Y-direction flat magnetic field transposition, and X '9、y′9 and Z' 9 are the momentums along the X direction, the Y direction and the Z direction of the quadrupole magnet are transferred through the second Y-direction flat magnetic field transposition;
12 After the proton beam flows out of the second Y-direction flat magnetic field transposed quadrupole magnet and drifts through a fifth beam drift section, the transverse-longitudinal ratio of the proton beam gradually becomes smaller in the drifting process, and the movement state of the proton beam before entering the second high-order magnet through the fifth beam drift section is as follows:
Wherein, R x10、Ry10 and R z10 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, R xx5、Ryy5 and R zz5 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, X 10、y10 and Z 10 are positions in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, X '10、y′10 and Z' 10 are momentums in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, and Δs 5 is a distance of the fifth beam drift section;
13 When the proton beam drifts to the transverse-longitudinal ratio of less than or equal to 1:4, the proton beam passes through the magnetic center of the second section of high-order magnet; the magnetic field generated by the second high-order magnet is linearly and slowly changed when approaching to the magnetic center along the Y direction and rapidly increased when being away from the magnetic center, so that the proton beam current in the Y direction away from the magnetic center is subjected to larger magnetic field force to lead to filarization and gradually approaches to synchronous particles in the center; after passing through the second high-order magnet, the proton beam drifts, and in the drifting process, particles far away from the center of the proton beam are subjected to stronger force to move towards the center, so that the original Gaussian-distributed proton beam is gradually and uniformly distributed along the Y direction, and the motion state of the second-section high-order magnet after the beam passes through is as follows:
wherein, R x、Ry and R z are respectively motion state matrixes of X direction, Y direction and Z direction after passing through the second high-order magnet, And/>The transmission matrix is respectively a transmission matrix passing through the second high-order magnet along the X direction, the Y direction and the Z direction, f x6 and f y6 are respectively the focusing intensities of the second high-order magnet along the X direction and the Y direction, X, Y and Z are respectively the positions passing through the second high-order magnet along the X direction, the Y direction and the Z direction, and X ', Y ' and Z ' are respectively the momentums passing through the second high-order magnet along the X direction, the Y direction and the Z direction;
By setting the focusing intensities f x1 and f y1 of the first X-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, respectively, the focusing intensities f x2 and f y2 of the second X-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, the focusing intensities f x3 and f y3 of the first high-order magnet in the X-direction and the Y-direction, the focusing intensities f x4 and f y4 of the first Y-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, the focusing intensities f x5 and f y5 of the second Y-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, focusing intensities f x6 and f y6 of the second high-order magnet in the X direction and the Y direction, a distance Deltas 1 of the first beam drift section, a distance Deltas 2 of the second beam drift section, a distance Deltas 3 of the third beam drift section, a distance Deltas 4 of the fourth beam drift section and a distance Deltas 5 of the fifth beam drift section, so that beams in the X direction and the Y direction are homogenized,
The cross section of the proton beam passing through the second high-order magnet is gradually changed into a rectangular beam which is uniformly distributed.
In this embodiment, the proton beam cross-sectional dimension is mainly controlled by the beam shaping transmission line; in order to meet the requirement of proton beam homogenization with the central energy of 100MeV/u, the working magnetic field gradient of the first X-direction flat magnetic field transposed quadrupole magnet is-12.5T/m, the corresponding effective length is 150mm, and the physical center of the magnet is 10841.08mm away from the entrance of the beam current collecting section; the length of the first beam drift section is 50mm; the working magnetic field gradient of the second X-direction flat magnetic field transposed quadrupole magnet is-12.6T/m, and the effective length of the corresponding magnet is 150mm; the length of the second beam drift section is 500mm; the working magnetic field gradient of the first high-order magnet is-3914T/m 3, and the effective length of the corresponding magnet is 400mm; the length of the third beam drift section is 200mm; the working magnetic field gradient of the first Y-direction flat magnetic field transposed quadrupole magnet is 15.5T/m, and the effective length of the corresponding magnet is 300mm; the length of the beam drift section of the fourth section is 200mm; the working magnetic field gradient of the second Y-direction flat magnetic field transposed quadrupole magnet is-12.5T/m, and the effective length of the corresponding magnet is 300mm; the working magnetic field gradient of the second high-order magnet is-1879T/m 3, and the effective length of the magnet is 300mm.
In this embodiment, with reference to engineering availability, the values of the focusing intensities f x1、fx2、fx4 and f x5 in the X direction of the first and second X-direction and first and second Y-direction flat magnetic field transposed quadrupole magnets are between-19 to +19t/m, the focusing intensities f Y1、fy2、fy4 and f y5 in the X direction of the first and second X-direction and first and second Y-direction flat magnetic field transposed quadrupole magnets are opposite numbers to each other, the focusing intensities f x3、fx6 in the X direction of the first and second high-order magnets are between-1000 to-4000T/m 3, and the focusing intensities f y3 and f y6 in the Y direction of the first and second high-order magnets are opposite numbers to each other to f x3 and f x6.
The beam homogenization process is shown in fig. 3, and simulation results of the influence of the high-order magnet on the proton beam distribution in the X direction and the Y direction are shown, wherein the vertical three columns are respectively the loading simulation results of the first high-order magnet in the magnetic field gradient of 0, -500 and-1000T/m 3; the horizontal three rows are the loading simulation results of the second higher order magnet at magnetic field gradients of 0, -1050 and-2100T/m 3, respectively. Through the beam homogenization process, the original Gaussian-distributed circular beam is optimized into uniformly-distributed rectangular beam, and the beam shape has higher efficiency and accuracy for proton cancer treatment.
Fig. 4 is a diagram showing the comparison of the effects of the cross-sectional shapes of proton beams of different sizes obtained after beam shaping the transmission line with the corresponding homogenized shapes, from top to bottom, before and after homogenization of beam spots of different sizes. The beam clusters with different sizes, which are not subjected to beam homogenization after the beam shaping transmission line, are arranged on the left side, and the beam clusters with the corresponding sizes after beam homogenization are arranged on the right side, so that the beam homogenization effect can be determined by comparison.
As shown in fig. 5, the first X-direction flat magnetic field transposed quadrupole magnet and the second X-direction flat magnetic field transposed quadrupole magnet are identical in structure, and the first Y-direction flat magnetic field transposed quadrupole magnet and the second Y-direction flat magnetic field transposed quadrupole magnet are identical in structure, and the quadrupole magnets include a quadrupole frame, first to fourth poles, and four coils; the inner edge of the quadrupole frame is respectively provided with a first quadrupole head and a second quadrupole head, the first quadrupole heads and the second quadrupole heads are distributed in a central symmetry mode, the centers of the tops of the first quadrupole heads and the second quadrupole heads are provided with spaces, proton beams pass through the spaces of the centers of the tops, corresponding current coils are wound on each pole head, and the four current coils are respectively connected to a power supply; the power supplies are respectively four current coils for supplying direct current, and the polarities of the corresponding pole heads are controlled by controlling the direction of the direct current; the polarities of the first and third polar heads are consistent and the polarities of the second and fourth polar heads are consistent, the polarities of the polar heads determine the focusing and defocusing directions of a magnetic field generated by the quadrupole magnet, and the magnetic field is focused in one direction and defocused in the vertical direction; the magnetic field direction of the quadrupole magnet is controlled by controlling the polarities of the first to fourth poles, so that the focusing or defocusing function of the quadrupole magnet on the proton beam in the appointed direction is realized; the first and second X-direction flat magnetic field transposed quadrupole magnets adopt first and third poles as N poles and second and fourth poles as S poles, magnetic fields generated by the quadrupole magnets are defocused in the X direction and focused in the Y direction, the first and second Y-direction flat magnetic field transposed quadrupole magnets adopt first and third poles as S poles and second and fourth poles as N poles, and magnetic fields generated by the quadrupole magnets are focused in the X direction and defocused in the Y direction.
As shown in fig. 6, the eight-stage magnet includes an eight-pole frame, first to eighth pole heads, and eight coils; the inner edge of the octupole frame is respectively provided with a first pole head to an eighth pole head, the first pole head to the eighth pole head are distributed in a central symmetry way, the center of the top end of the first pole head to the eighth pole head is provided with a space, proton beam passes through the space in the center of the top end, each pole head is wound with a corresponding current coil, and the eight current coils are respectively connected to a power supply; the power supplies are respectively eight current coils for supplying direct current, and the polarities of the corresponding pole heads are controlled by controlling the direction of the direct current; the polarities of the first, third, fifth and seventh pole pieces are identical and the polarities of the second, fourth, sixth and eighth pole pieces are identical, the polarities of the pole pieces determine the directions of focusing and defocusing of the magnetic field generated by the octant magnet, focusing in one direction and defocusing in the vertical direction, and likewise defocusing in one direction and focusing in the vertical direction; the magnetic field direction of the octapole magnet is controlled by controlling the polarities of the first to eighth pole heads, so that the focusing or defocusing function of the octapole magnet on the proton beam in the appointed direction is realized.
Finally, it should be noted that the examples are disclosed for the purpose of aiding in the further understanding of the present invention, but those skilled in the art will appreciate that: various alternatives and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the invention should not be limited to the disclosed embodiments, but rather the scope of the invention is defined by the appended claims.

Claims (5)

1. A method for homogenizing a laser-accelerated proton beam, the method comprising the steps of:
1) Setting a laser acceleration proton beam homogenization system:
A beam collecting section, an energy selecting section, a beam homogenizing transmission line and a beam shaping transmission line are sequentially arranged along the beam transmission direction; the beam current generated by laser targeting passes through a beam current collecting section and an energy selecting section to obtain proton beam current with ideal energy; the transverse distribution of the proton beam with ideal energy is Gaussian distribution, ideal energy particles pass through a beam homogenization transmission line to finish the operation of beam uniform distribution, and finally the uniform proton beam with rectangular cross section is obtained through the beam homogenization transmission line; the proton beam after passing through the beam collecting section and the energy expanding and selecting section enters a beam homogenizing transmission line and moves along the Z direction; the proton beam transmitted to the beam homogenization transport line is circular beam distributed in Gaussian in the XOY plane, and the center of the beam is synchronous particle, namely particle moving in ideal state;
a first X-direction flat magnetic field transposition quadrupole magnet, a second X-direction flat magnetic field transposition quadrupole magnet, a first high-order magnet, a first Y-direction flat magnetic field transposition quadrupole magnet, a second Y-direction flat magnetic field transposition quadrupole magnet and a second high-order magnet are sequentially arranged in the beam homogenization transmission line; the magnetic fields generated by the first and second X-direction flat magnetic field transposed quadrupole magnets defocus the proton beam in the X direction and focus the proton beam in the Y direction; the placement distance between the second X-direction flat magnetic field transposed quadrupole magnet and the first X-direction flat magnetic field transposed quadrupole magnet is as short as possible, and only the installation position is reserved; a distance is reserved between the first high-order magnet and the second X-direction flat magnetic field transposed quadrupole magnet; the magnetic fields generated by the first and second Y-direction flat magnetic field transposed quadrupole magnets defocus the proton beam in the Y direction and focus the proton beam in the X direction; the placement distance between the second Y-direction flat magnetic field transposed quadrupole magnet and the second Y-direction flat magnetic field transposed quadrupole magnet is as short as possible, and only the installation position is reserved; a distance is reserved between the second high-order magnet and the second Y-direction flat magnetic field transposed quadrupole magnet; the distance between the installation centers of the first X-direction flat magnetic field transposition quadrupole magnet and the second X-direction flat magnetic field transposition quadrupole magnet is a first beam drift section, the distance between the second X-direction flat magnetic field transposition quadrupole magnet and the first high-order magnet is a second beam drift section, the distance between the first high-order magnet and the first Y-direction flat magnetic field transposition quadrupole magnet is a third beam drift section, the distance between the first Y-direction flat magnetic field transposition quadrupole magnet and the installation centers of the second Y-direction flat magnetic field transposition quadrupole magnet is a fourth beam drift section,
The distance between the second Y-direction flat magnetic field transposed quadrupole magnet and the second high-order magnet is a fifth beam drift section;
2) The motion state of the beam before entering the beam homogenization transmission line is as follows:
Wherein, R x0、x0 and X ′ 0 are respectively the motion state matrix, the position and the momentum in the X direction before entering the beam homogenization transmission line; r y0、y0 and Y 0 ′ are respectively a motion state matrix, a position and momentum in the Y direction before entering the beam homogenization transmission line; r z0、z0 and Z ′ 0 are respectively a motion state matrix, a position and momentum in the Z direction before entering the beam homogenization transmission line;
3) Proton beam current taking synchronous particles as the center passes through the magnetic center of the first X-direction flat magnetic field transposed quadrupole magnet along the Z-axis direction, the proton beam current is compressed along the Y-direction while being stretched along the X-direction under the action of a magnetic field, the stretching degree of the X-direction is respectively in direct proportion to the strength and the drift distance of the magnetic field, the strength of the magnetic field is in direct proportion to the applied current, the stretching size is increased along with the increase of the drift distance of the proton beam current and the increase of the magnet current, and the motion state of the beam current after passing through the first X-direction flat magnetic field transposed quadrupole magnet is as follows:
wherein, R x1、Ry1 and R z1 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the first X direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the four-pole magnet are respectively transmitted through the first X-direction flat magnetic field transposition, f x1 and f y1 are respectively the focusing intensities along the X direction and the Y direction of the four-pole magnet, X 1、y1 and Z 1 are respectively the positions along the X direction, the Y direction and the Z direction of the four-pole magnet through the first X-direction flat magnetic field transposition, and X ′ 1、y′ 1 and Z ′ 1 are respectively the momentums along the X direction, the Y direction and the Z direction of the four-pole magnet through the first X-direction flat magnetic field transposition;
4) The proton beam enters the second X-direction flat magnetic field transposition quadrupole magnet through the first beam drift section after passing through the first X-direction flat magnetic field transposition quadrupole magnet, and the movement state before the beam enters the second X-direction flat magnetic field transposition quadrupole magnet through the first beam drift section is as follows:
Wherein, R x2、Ry2 and R z2 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the first beam drift section, R xx1、Ryy1 and R zz1 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the first beam drift section, X 2、y2 and Z 2 are positions in the X direction, the Y direction and the Z direction after passing through the first beam drift section, X ′ 2、y′ 2 and Z ′ 2 are momentums in the X direction, the Y direction and the Z direction after passing through the first beam drift section, Δs 1 is a distance of the first beam drift section, and γ is a relative speed of the beam;
5) The beam flow enters the second X-direction flat magnetic field transposition quadrupole magnet after passing through the first beam flow drift section, the synchronous particles pass through the magnetic center of the second X-direction flat magnetic field transposition quadrupole magnet, the proton beam flow is compressed along the Y direction while continuously stretching along the X direction under the action of the magnetic field, the proton beam flow is stretched along the X direction and compressed along the Y direction by passing through the first and the second X-direction flat magnetic field transposition quadrupole magnets, the X direction of the proton beam flow has flattening trend, and the movement state of the beam flow after passing through the second X-direction flat magnetic field transposition quadrupole magnet is as follows:
Wherein, R x3、Ry3 and R z3 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the second X direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transpose quadrupole magnet are respectively shown, f x2 and f y2 are respectively shown as the focusing intensities along the X direction and the Y direction of the second X-direction flat magnetic field transpose quadrupole magnet, X 3、y3 and Z 3 are respectively shown as the positions along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transpose quadrupole magnet, and X ′ 3、y′ 3 and Z ′ 3 are respectively shown as the momentums along the X direction, the Y direction and the Z direction of the second X-direction flat magnetic field transpose quadrupole magnet;
6) After the proton beam comes out of the second X-direction flat magnetic field transposed quadrupole magnet, the proton beam drifts through a second beam drift section, the transverse-longitudinal ratio of the proton beam gradually becomes larger in the drifting process, and the motion state of the proton beam before entering the first high-order magnet through the second beam drift section is as follows:
wherein, R x4、Ry4 and R z4 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the second beam drift section, R xx2、Ryy2 and R zz2 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the second beam drift section, X 4、y4 and Z 4 are positions in the X direction, the Y direction and the Z direction after passing through the second beam drift section, X ′ 4、y′ 4 and Z ′ 4 are momentums in the X direction, the Y direction and the Z direction after passing through the second beam drift section, and Δs 2 is a distance of the second beam drift section;
7) When the proton beam drifts to the transverse-longitudinal ratio of more than or equal to 4:1, the proton beam passes through the magnetic center of the first high-order magnet; the magnetic field generated by the first high-order magnet is linearly and slowly changed along the X direction when approaching to the magnetic center, and is rapidly increased when being far away from the magnetic center, so that the proton beam current in the X direction far from the magnetic center is subjected to larger magnetic field force to further lead to filamentization and gradually approaches to synchronous particles in the center; the motion state of the beam flow before passing through the first high-order magnet is as follows:
Wherein, R x5、Ry5 and R z5 are respectively motion state matrixes of X direction, Y direction and Z direction after passing through the first high-order magnet, And/>The transmission matrix is respectively a transmission matrix passing through the first high-order magnet along the X direction, the Y direction and the Z direction, f x3 and f y3 are respectively the focusing intensities of the first high-order magnet along the X direction and the Y direction, X 5、y5 and Z 5 are respectively the positions passing through the first high-order magnet along the X direction, the Y direction and the Z direction, and X ′ 5、y′ 5 and Z ′ 5 are respectively the momentums passing through the first high-order magnet along the X direction, the Y direction and the Z direction;
8) After the proton beam passes through the first high-order magnet, the proton beam drifts through a third beam drift section, in the drifting process, particles far away from the center of the proton beam are subjected to stronger force to move towards the center, so that the proton beam originally in Gaussian distribution is gradually and uniformly distributed along the X direction, and the movement state of the beam before entering the first Y-direction flat magnetic field transposed quadrupole magnet through the third beam drift section is as follows:
wherein, R x6、Ry6 and R z6 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the third beam drift section, R xx3、Ryy3 and R zz3 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the third beam drift section, X 6、y6 and Z 6 are positions in the X direction, the Y direction and the Z direction after passing through the third beam drift section, X ′ 6、y′ 6 and Z ′ 6 are momentums in the X direction, the Y direction and the Z direction after passing through the third beam drift section, and Δs 3 is a distance of the third beam drift section;
9) Proton beam flows which are uniformly distributed along the X direction enter a first Y-direction flat magnetic field transposed quadrupole magnet to be decoupled in the Y direction; synchronous particles pass through the magnetic center of the first Y-direction flat magnetic field transposed quadrupole magnet, proton beam current is compressed along the X direction while being stretched along the Y direction under the action of a magnetic field, the stretching degree of the Y direction is respectively in direct proportion to the strength and the drift distance of the magnetic field, the stretching size is increased along with the increase of the drift distance of the proton beam current and the increase of the magnet current, and the movement state of the beam current after passing through the first Y-direction flat magnetic field transposed quadrupole magnet is as follows:
Wherein, R x7、Ry7 and R z7 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the first Y direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the four-pole magnet are respectively transmitted through the first Y-direction flat magnetic field transposition, f x4 and f y4 are respectively the focusing intensities along the X direction and the Y direction of the four-pole magnet, X 7、y7 and Z 7 are respectively the positions along the X direction, the Y direction and the Z direction of the four-pole magnet through the first Y-direction flat magnetic field transposition, and X ′ 7、y′ 7 and Z ′ 7 are respectively the momentums along the X direction, the Y direction and the Z direction of the four-pole magnet through the first Y-direction flat magnetic field transposition;
10 The proton beam enters the second Y-direction flat magnetic field transposed quadrupole magnet through the fourth beam drift section after passing through the first Y-direction flat magnetic field transposed quadrupole magnet, and the motion state before the beam enters the second Y-direction flat magnetic field transposed quadrupole magnet through the fourth beam drift section is as follows:
wherein, R x8、Ry8 and R z8 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, R xx4、Ryy4 and R zz4 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, X 8、y8 and Z 8 are positions in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, X ′ 8、y′ 8 and Z ′ 8 are momentums in the X direction, the Y direction and the Z direction after passing through the fourth beam drift section, and Δs 4 is a distance of the fourth beam drift section;
11 Synchronous particles pass through the magnetic center of the second Y-direction flat magnetic field transposed quadrupole magnet, the proton beam is compressed along the X direction while being stretched along the Y direction under the action of the magnetic field, the proton beam is stretched along the Y direction and compressed along the X direction by the first and second Y-direction flat magnetic field transposed quadrupole magnets, the Y direction of the proton beam has flattening trend, and the movement state of the beam after passing through the second Y-direction flat magnetic field transposed quadrupole magnet is as follows:
Wherein, R x9、Ry9 and R z9 are respectively motion state matrixes of X direction, Y direction and Z direction after the quadrupole magnet is transposed by the second Y direction flat magnetic field, And/>The transmission matrices along the X direction, the Y direction and the Z direction of the second Y-direction flat magnetic field transpose quadrupole magnet are respectively shown, f x5 and f y5 are respectively shown as the focusing intensities along the X direction and the Y direction of the second Y-direction flat magnetic field transpose quadrupole magnet, X 9、y9 and Z 9 are respectively shown as the positions along the X direction, the Y direction and the Z direction of the second Y-direction flat magnetic field transpose quadrupole magnet, and X ′ 9、y′ 9 and Z ′ 9 are respectively shown as the momentums along the X direction, the Y direction and the Z direction of the second Y-direction flat magnetic field transpose quadrupole magnet;
12 After the proton beam flows out of the second Y-direction flat magnetic field transposed quadrupole magnet and drifts through a fifth beam drift section, the transverse-longitudinal ratio of the proton beam gradually becomes smaller in the drifting process, and the movement state of the proton beam before entering the second high-order magnet through the fifth beam drift section is as follows:
Wherein, R x10、Ry10 and R z10 are motion state matrices in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, R xx5、Ryy5 and R zz5 are transmission matrices in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, X 10、y10 and Z 10 are positions in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, X ′ 10、y′ 10 and Z ′ 10 are momentums in the X direction, the Y direction and the Z direction after passing through the fifth beam drift section, and Δs 5 is a distance of the fifth beam drift section;
13 When the proton beam drifts to the transverse-longitudinal ratio of less than or equal to 1:4, the proton beam passes through the magnetic center of the second high-order magnet; the magnetic field generated by the second high-order magnet is linearly and slowly changed when approaching to the magnetic center along the Y direction and is rapidly increased when being away from the magnetic center, so that the proton beam current in the Y direction away from the magnetic center is subjected to larger magnetic field force to further lead to filamentization and gradually approaches to synchronous particles in the center; after passing through the second high-order magnet, the proton beam drifts, and in the drifting process, particles far away from the center of the proton beam are subjected to stronger force to move towards the center, so that the original Gaussian-distributed proton beam is gradually and uniformly distributed along the Y direction, and the motion state of the second high-order magnet after the beam passes through is as follows:
wherein, R x、Ry and R z are respectively motion state matrixes of X direction, Y direction and Z direction after passing through the second high-order magnet, And/>The transmission matrix is respectively a transmission matrix passing through the second high-order magnet along the X direction, the Y direction and the Z direction, f x6 and f y6 are respectively the focusing intensities of the second high-order magnet along the X direction and the Y direction, X, Y and Z are respectively the positions passing through the second high-order magnet along the X direction, the Y direction and the Z direction, and X ′、y′ and Z ′ are respectively the momentums passing through the second high-order magnet along the X direction, the Y direction and the Z direction;
By setting the focusing intensities f x1 and f y1 of the first X-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, respectively, the focusing intensities f x2 and f y2 of the second X-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, the focusing intensities f x3 and f y3 of the first high-order magnet in the X-direction and the Y-direction, the focusing intensities f x4 and f y4 of the first Y-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, the focusing intensities f x5 and f y5 of the second Y-direction flat magnetic field transposed quadrupole magnet in the X-direction and the Y-direction, the focusing intensities f x6 and f y6 of the second high-order magnet in the X direction and the Y direction, the distance delta s 1 of the first beam drift section, the distance delta s 2 of the second beam drift section, the distance delta s 3 of the third beam drift section, the distance delta s 4 of the fourth beam drift section and the distance delta s 5 of the fifth beam drift section enable beams in the X direction and the Y direction to be uniform, and the cross section of the proton beam passing through the second high-order magnet is gradually changed into a uniformly distributed rectangular beam.
2. The homogenization method of claim 1, wherein the beam collection section includes: three superconducting solenoids connected in sequence, each solenoid is connected by a vacuum pipeline, and a beam diagnosis element is arranged in the vacuum pipeline.
3. The homogenization method of claim 1, wherein the energy selection section includes: the first and second quadrupole magnets, the first horizontal 45-degree deflection magnet, the third and fourth quadrupole magnets and the second horizontal 45-degree deflection magnet are sequentially connected.
4. The homogenization method of claim 1, wherein the beam shaping transmission line includes: the three quadrupolar magnets are sequentially connected, and adjacent quadrupolar magnets are connected through vacuum pipelines.
5. The homogenization method of claim 1, wherein the first and second higher order magnets are octapole magnets.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113301705A (en) * 2021-05-21 2021-08-24 中国科学院近代物理研究所 Linear injector system, method for operating the same, and proton heavy ion cancer treatment device
CN113398497A (en) * 2021-07-19 2021-09-17 北京大学 Dose delivery system for laser-accelerated proton cancer treatment device

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US20200047004A1 (en) * 2018-08-13 2020-02-13 HIL Applied Medical Ltd. Beam Delivery System For Proton Therapy For Laser-Accelerated Protons

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* Cited by examiner, † Cited by third party
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CN113301705A (en) * 2021-05-21 2021-08-24 中国科学院近代物理研究所 Linear injector system, method for operating the same, and proton heavy ion cancer treatment device
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