CN117042278A - Medical miniaturized ion accelerator - Google Patents
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- CN117042278A CN117042278A CN202310943623.1A CN202310943623A CN117042278A CN 117042278 A CN117042278 A CN 117042278A CN 202310943623 A CN202310943623 A CN 202310943623A CN 117042278 A CN117042278 A CN 117042278A
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- H—ELECTRICITY
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- 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
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- H—ELECTRICITY
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- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
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Abstract
The present disclosure provides a medical miniaturized ion accelerator comprising: an ion source for generating low energy ions having an initial energy; the linear accelerator is used for primarily accelerating low-energy ions to obtain medium-energy beam current; the synchronous accelerator is used for accelerating the medium-energy beam to obtain high-energy beam of target energy; the synchrotron comprises: the two deflection units are connected end to end through two straight sections and are used for deflecting the beam in the synchrotron, and the deflection angle of each deflection unit is 180 degrees; the focusing units are in one-to-one correspondence with the straight sections and are arranged on the straight sections and are used for focusing the beam current in the synchrotron in the horizontal direction and the vertical direction; the high-frequency accelerating cavity is arranged on a straight line section and is used for accelerating beam current in the synchrotron; the injection system is arranged on the two straight sections and is used for introducing medium energy beam current into the synchrotron; and the slow extraction system is arranged on the two straight sections and is used for extracting high-energy beam current of target energy obtained after acceleration.
Description
Technical Field
The present disclosure relates to the field of medical devices, and more particularly, to a medical miniaturized ion accelerator.
Background
Ion beams (meaning ions of the periodic table of hydrogen, helium, lithium, carbon and oxygen ions having mass numbers not exceeding 20, and suitable for ion therapy) have a physical effect called bragg peaks, which means that the amount of energy deposited by an ion beam in a substance is inversely related to the magnitude of the energy, and the energy release reaches a peak before the movement of the ions is stopped, and then the energy deposition is drastically reduced. Due to the existence of Bragg peak, the ion beam can accurately kill tumor cells with little damage to surrounding healthy tissues. In addition, ion beams have a higher relative biological effect than conventional radiation, i.e., the physical absorbed dose required to achieve the same biological effect (e.g., 10% survival of cells) is less than that of conventional radiation, thereby significantly reducing the number of treatments for the patient.
The existing ion treatment accelerator has large occupied area and high investment cost, so that the accelerator is difficult to popularize. The invention mainly reduces the cost of the synchrotron, including reducing the number of elements, reducing the manufacturing and mounting cost of main elements, reducing the occupied area and the like.
An existing ion treatment device (application number is 201010252492.5) deflects an ion beam by a plurality of diode magnets to form a closed track, and quadrupole magnets are arranged among the diode magnets to realize the focusing effect on the ion beam in the horizontal direction and the vertical direction. The circumference of the existing ion treatment device is larger than 50m, the weight of the single dipolar magnet is close to 20 tons, the manufacturing cost and the installation difficulty are high, and in order to install, a large gantry crane is needed, and the space requirement is high. Another ion treatment device (application No. 202110638036.2) employs a composite superconducting magnet with a composite quadrupole field on a dipole field, which is more compact than an accelerator structure consisting of conventional magnets. But the extraction scheme adopts vertical extraction, and deflection iron used for extraction can introduce dispersion in the vertical direction of the high-energy beam line. Generally, the ion beam has a certain energy dispersion, and the dispersion will increase the overall size of the ion beam, so a section of beam line is specially designed on the high-energy beam line to eliminate the dispersion. Both the introduction and the elimination of chromatic dispersion can only be through a diode magnet. Since the dipole magnet in the synchrotron typically deflects particles in the horizontal direction, dispersion in the horizontal direction is inherent, and hence the high-energy beam always needs to be subjected to dispersion cancellation in the horizontal direction, regardless of whether the beam is extracted in the horizontal direction or the vertical direction. The vertical extraction scheme increases the design difficulty and debugging difficulty of the whole high-energy beam line because dispersion elimination in both horizontal and vertical directions is required.
Disclosure of Invention
In view of the above, the present invention provides a miniaturized ion accelerator for medical use to solve the above problems.
One aspect of the present disclosure provides a medical miniaturized ion accelerator comprising: an ion source for generating low energy ions having an initial energy; the linear accelerator is used for primarily accelerating the low-energy ions to obtain a medium-energy beam; the synchronous accelerator is used for accelerating the medium-energy beam to obtain high-energy beam with target energy; the synchrotron comprises: the two deflection units are connected end to end through two straight sections and are used for deflecting the beam in the synchronous accelerator, and the deflection angle of each deflection unit is 180 degrees; the two focusing units are in one-to-one correspondence with the straight line sections and are arranged on the straight line sections and used for focusing the beam current in the synchrotron in the horizontal direction and the vertical direction; the high-frequency accelerating cavity is arranged on one straight section and is used for accelerating beam current in the synchrotron; the injection system is arranged on the two straight sections and is used for introducing medium energy beam current to the synchrotron; and the slow extraction system is arranged on the two straight sections and is used for extracting high-energy beam current of target energy obtained after acceleration.
Optionally, a stripping film is installed between the linear accelerator and the synchrotron, and is used for converting ions in the medium-energy beam into ions required for treatment.
Optionally, the injection mode of the injection system is multi-turn injection, and the injection system comprises: an injection cutting magnet for injecting the medium energy beam into the synchrotron; the injection convex rail magnets are respectively arranged on the two straight line sections and are used for forming local convex rails with gradually reduced heights, and the horizontal acceptance of the synchronous accelerator is adjusted to the position of the outlet of the injection static deflection plate; the injection static deflection plate is arranged on one of the two linear sections, is connected with the injection cutting magnet, and is used for providing a transverse kicker angle for the medium energy beam so that the medium energy beam enters the horizontal receiving degree of the synchronous accelerator and gradually fills the whole horizontal receiving degree along with the descent of the convex rail.
Optionally, the slow extraction system comprises: the outgoing electrostatic deflection plate and the outgoing cutting magnet are respectively arranged on the two straight sections and adjacent to the focusing unit, and the phase shift of the outgoing electrostatic deflection plate and the outgoing cutting magnet is 270 degrees and is used for outgoing high-energy beam current of target energy obtained after acceleration.
Optionally, each of the focusing units comprises three quadrupole magnets.
Optionally, the slow extraction system comprises: and the plurality of lead-out convex rail magnets are respectively arranged on the two straight sections and are used for forming local convex rails at the lead-out electrostatic deflection plates so that the beam current in the synchronous accelerator is close to the polar plates of the lead-out electrostatic deflection plates.
Optionally, the slow extraction system further comprises: two resonant hexapole irons symmetrically arranged on the two straight line sections and adjacent to the quadrupole magnets at one end of the focusing unit on the corresponding straight line section, and are used for inducing beam third-order resonance in the synchrotron and forming a stable triangle in a phase space; two chromaticity correction hexapole irons are symmetrically arranged on the two straight line sections and are adjacent to a quadrupole magnet at the other end of the focusing unit on the corresponding straight line section, and the two chromaticity correction hexapole irons are used for adjusting chromaticity to enable particle extraction phase diagrams with different energies in beam current in the synchronous accelerator to overlap, so that extraction efficiency is improved; and the extraction excitation (12) is arranged on one section of the straight line section and is used for generating a transverse high-frequency electric field to enable the amplitude of the particle motion to be larger, gradually leaves the stable triangle and is extracted.
Optionally, each of the deflection units is formed by combining a plurality of superconducting secondary magnets.
Optionally, the ion source is an electron cyclotron resonance ion source.
Optionally, the linac includes: a radio frequency quadrupole field accelerator for accelerating low energy ions extracted from the ion source to an energy level of 0.6 MeV/u; and the drift tube linear accelerator is used for accelerating the low-energy ions accelerated by the radio-frequency quadrupole field accelerator to an energy level of 4-7 MeV/u.
The above at least one technical scheme adopted in the embodiment of the disclosure can achieve the following beneficial effects:
the medical miniaturized ion accelerator provided by the embodiment of the disclosure reduces the number of components in the synchrotron as much as possible, the components outside the dipolar iron are concentrated on two straight sections, the space utilization rate is greatly improved, the perimeter of the accelerator is shortened, the whole perimeter is not more than 30 meters, the occupied area of the whole device is small, the construction cost is low, and the unique optical design ensures that the aperture of the dipolar magnet is small, so that the manufacturing cost and the power consumption of the dipolar magnet are effectively controlled.
Drawings
For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
FIG. 1 schematically illustrates a schematic diagram of a miniaturized heavy ion synchrotron provided by an embodiment of the present disclosure;
FIG. 2 schematically illustrates envelope functions and dispersion functions in both horizontal and vertical directions of a synchrotron provided by an embodiment of the present disclosure;
fig. 3 schematically shows a trajectory diagram of a beam injection process;
FIG. 4 schematically illustrates a trace of the beam of FIG. 2 forming a partial track at the lead-out electrostatic deflection under the influence of the lead-out track magnet;
fig. 5 schematically shows the trajectory of the beam at the last three turns before extraction and the trajectory after entering the electrostatic deflector plate.
Reference numerals:
1-an ion source; a 2-linac; 3-synchrotron; a 4-deflection unit; 5-a high frequency acceleration chamber; 6-peeling film; 7-injecting a cutting magnet; 8-injecting an electrostatic deflector plate; 9-injecting a convex rail magnet; 10-leading out an electrostatic deflection plate; 11-extracting a cutting magnet; 12-extracting excitation; 13-quadrupole magnets; 14-leading out a convex rail magnet; 15-resonating hexapole iron; 16-chromaticity correction hexapole iron.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
As shown in fig. 1, an embodiment of the present disclosure provides a medical miniaturized ion accelerator including an ion source 1, a linac 2, and a synchrotron 3. The ion source 1 is used for generating low-energy ions with initial energy; the linear accelerator 2 is used for primarily accelerating low-energy ions to obtain a medium-energy beam; the synchrotron 3 is used to accelerate the medium energy beam to obtain a high energy beam of the target energy.
The ion source 1 is a conventional electron cyclotron resonance ion source, and a laser ion source may be used. The laser ion source is a novel ion source for generating multi-charge state ion beam current, has the characteristics of high current intensity, short pulse time of the beam current and the like, but the whole technology is difficult to achieve, and is still immature at present. In the present embodiment, the ion source 1 employs an electron cyclotron resonance ion source.
The linac 2 includes: a radio frequency quadrupole field accelerator for accelerating low energy ions extracted from the ion source 1 to an energy level of 0.6 MeV/u; a drift tube linac for accelerating low energy ions after acceleration by a radio frequency quadrupole field accelerator to an energy level of 4-7 MeV/u.
A stripping film 6 is installed between the linac 2 and the synchrotron 3 for converting ions in the medium energy beam into ions required for treatment. The linear accelerator 2 can accelerate different kinds of ions on the premise that the charge-to-mass ratios of the ions are similar, and common ions for treatment such as protons H + Or carbon ions 12 C 6+ The same linear accelerator 2 cannot be used for acceleration due to the difference in the equal charge-to-mass ratio. Thus, the ion source 1 generally generates as 3 H + ， 12 C 4+ Ions of the same equivalent charge-to-mass ratio are accelerated and converted into H by the stripping film 6 + Or (b) 12 C 6+ 。
As shown in fig. 1, the synchrotron 3 includes: two deflection units 4, two focusing units, a high frequency acceleration chamber 5, an injection system and a slow extraction system.
The two deflection units 4 are connected end to end by two straight sections for deflecting the beam in the synchrotron 3, the deflection angle of each deflection unit 4 being 180 °. The deflection unit 4 may be composed of one or more superconducting diode magnets, the processing difficulty of the large-angle superconducting diode iron is high, and the size of the whole deflection unit 4 is large due to the plurality of small-angle superconducting diode magnets. In the present embodiment, each deflection unit 4 is composed of a plurality of superconducting secondary magnets, one of which is preferably composed of 4 45 ° diode magnets as shown in fig. 1. The superconducting diode magnet is an inclined solenoid type diode magnet, has the characteristics of high magnet field intensity, capability of easily combining various magnetic fields and the like, and generates a diode magnetic field by using two layers of coils, and a quadrupole magnetic field can be generated by sleeving two layers of coils outside the two layers of coils.
In a less preferred embodiment, the quadrupole magnetic field in the deflection unit can also be realized by using independent quadrupole irons, so that the design difficulty of the superconducting diode irons is reduced, but the circumference of the whole accelerator is slightly increased.
Fig. 2 shows the envelope function (β function) and the dispersion function of the synchrotron 3 in both the horizontal and vertical directions. The envelope function and the dispersion function together determine the lateral dimensions of the beam within the synchrotron 3, where the beam envelope is generally expressed as:
where ε represents the emittance of the beam and σ represents the momentum dispersion of the beam.
The difficulty of processing a superconducting diode magnet is positively correlated to its size. The design of the embodiment of the disclosure enables the envelope function in the diode iron to be small, so that the beam size in the diode iron is small, the size of the superconducting diode magnet is reduced, and the processing difficulty is reduced.
The focusing units are arranged on the straight sections in one-to-one correspondence with the straight sections. In this embodiment, each focusing unit comprises three quadrupole magnets 13. For achieving focusing of the beam in horizontal and vertical directions in cooperation with a quadrupole field in the deflection unit.
The high-frequency accelerating cavity 5 is arranged on a straight line section and is used for accelerating the beam current in the synchrotron 3. In practical application, the high-frequency accelerating cavity 5 can accelerate or decelerate the beam, the beam in the synchrotron 3 is firstly captured by high-frequency insulation to form a beam cluster, and the periodic movement of the beam cluster and the periodic variation of the accelerating electric field can be kept in strict synchronization by adjusting the frequency of the high-frequency accelerating cavity 5 and the rising speed of the magnetic field, so that the beam cluster can be continuously accelerated or decelerated in a constant track.
The injection system is arranged on two straight sections for introducing a medium energy beam into the synchrotron 3. The injection mode of the synchrotron 3 generally comprises single-circle injection, multi-circle injection, stripping injection and the like, and the single-circle injection involves less equipment, and the beam acceptance required by the accelerator is smaller because of only one injection, but the requirement on the injector for achieving the same ion number is higher; the beam gain is smaller due to the Liuwei theorem in multi-turn injection, and generally only has more than ten times of gain, but is suitable for the injection of different kinds of ions; and stripping injection, the ion in a low charge state is stripped into particles in a high charge state, so that the Liuwei theorem can be broken through, the gain of more than 50 times is realized, but only one ion can be injected. In order to enable the accelerator to be suitable for accelerating different ions and simultaneously reduce technical difficulty, the invention adopts an injection mode of multi-circle injection.
In this embodiment, the injection system includes: an injection cutting magnet 7, an injection electrostatic deflector plate 8 and a plurality of injection track magnets 9. The injection cutting magnet 7 is used for injecting the medium energy beam into the synchrotron 3; the injection convex rail magnets 9 are respectively arranged on the two straight line sections and are used for forming local convex rails with gradually reduced heights, and the horizontal acceptance of the synchrotron 3 is adjusted to the outlet of the injection static deflection plate 8; the injection static deflection plate 8 is arranged on one of the two straight sections, is connected with the injection cutting magnet 7, and is used for giving a transverse kicker to the medium energy beam so that the medium energy beam enters the horizontal receiving degree of the synchrotron 3 and gradually fills the whole horizontal receiving degree along with the descent of the convex rail. As shown in fig. 3, the beam is continuously injected, and as the strength of the injection track magnet 9 gradually decreases, the horizontal acceptance of the whole synchrotron is finally filled, so that the beam injection is completed. Alternatively, the number of injection track magnets 9 may be 2-4, preferably 3.
And the slow extraction system is arranged on the two straight sections and is used for extracting high-energy beam current of target energy obtained after acceleration. In this embodiment, the slow extraction system includes: an outgoing electrostatic deflection plate 10, an outgoing cutter magnet 11, three outgoing track magnets 14, two resonant hexapole irons 15, two chromaticity correction hexapole irons 16 and an outgoing excitation 12.
The extraction electrostatic deflection plate 10 and the extraction cutting magnet 11 are respectively arranged on two straight sections, are adjacent to the focusing unit, have a phase shift of 270 degrees and are used for extracting high-energy beam current of target energy obtained after acceleration.
The plurality of leading-out convex rail magnets 14 are respectively arranged on the two straight line sections and are used for forming local convex rails at the positions of leading-out static deflection plates, so that the beam current in the synchronous accelerator 3 approaches to the polar plates of the leading-out static deflection plates 10, and the positions outside the local convex rails are arranged on the central rail, thereby being beneficial to reducing the envelope of the leading-out beam current, ensuring the leading-out efficiency and avoiding the beam current loss at the static deflection plates in the injection and acceleration processes. Fig. 4 shows the leading-out convex rail, and the position of the starting point of the picture is the inlet position of the electrostatic deflection plate. Alternatively, the number of lead-out track magnets may be 2 to 4, preferably 3.
The two resonating hexapole irons 15 are symmetrically arranged on the two straight line sections and are adjacent to the quadrupole magnets 13 at one end of the focusing unit on the corresponding straight line sections, and are used for inducing the third-order resonance of the beam in the synchrotron 3 and forming a stable triangle in the phase space. When the amplitude increases to a certain extent, the particles enter the extraction electrostatic deflection plate and are extracted through the extraction cutting iron, and the extraction excitation 12 generates a transverse high-frequency electric field so that the amplitude of the particles originally positioned in the stable triangle is continuously increased and further leaves the stable area, so that the beam extraction is continuously and stably carried out.
The two chromaticity correction hexapole irons 16 are symmetrically arranged on two straight line sections and are adjacent to the quadrupole magnets 13 at the other end of the focusing unit on the corresponding straight line sections, and the chromaticity correction hexapole irons are used for adjusting chromaticity to enable particle extraction phase diagrams with different energies in beam current in the synchrotron 3 to overlap, so that hardt conditions are met, and extraction efficiency is improved.
An extraction excitation 12 is provided on a section of the straight section for generating a transverse high frequency electric field to increase the amplitude of the particle motion, gradually leaving the stable triangle and being extracted.
Fig. 5 is a graph of the trajectory of the beam exiting the last three turns before exiting and after entering the electrostatic deflector. Unlike the electrostatic deflection plate and the extraction cutter magnet 11, which are commonly used in medical synchrotrons, which have a phase shift of approximately 90 °, the electrostatic deflection plate and the extraction cutter magnet 11 are respectively placed on long straight sections of opposite sides in the embodiment of the present disclosure, and the phase shift therebetween is approximately 270 °. In the extraction design, the distance separating the extraction beam from the circulating beam at the entrance of the cutting magnet after the deflection of the electrostatic deflection plate is usually considered, the distance is used for mounting the polar plate of the cutting magnet, the magnitude of the distance is theoretically dependent on the thickness of the magnetic pole, and the deflection angle of the electrostatic deflection plate is determined,
wherein θ is a kick angle of the electrostatic deflector, β ES As a horizontal envelope function at the electrostatic deflection plate, beta MS As a horizontal envelope function at the cut magnet, (mu) MS -μ ES ) To cut the phase shift between the magnet and the electrostatic deflection plate. In the design, the electrostatic deflection plate and the extraction cutting magnet 11 are both close to the horizontal focusing quadrupole magnet 13, so that beta functions of positions of the electrostatic deflection plate and the extraction cutting magnet are all maximum, the phase shift between the electrostatic deflection plate and the cutting magnet can be about 270 degrees by optimizing the distribution of the beta functions, and according to a formula, the design can greatly improve the distance gap between an extraction beam and a circulating beam, and the requirements on an extraction element can be reduced, so that the beam current is stably extracted, and the size of the extraction element is reduced.
According to the scheme, the medical miniaturized ion accelerator provided by the implementation of the disclosure reduces the number of components in the synchrotron as much as possible, the components outside the dipolar iron are concentrated on two straight sections, the space utilization rate is greatly improved, the perimeter of the accelerator is shortened, the whole perimeter is not more than 30 m, the occupied area of the whole device is small, the construction cost is low, and the unique optical design ensures that the aperture of the dipolar magnet is small, so that the manufacturing cost and the power consumption of the dipolar magnet are effectively controlled.
Those skilled in the art will appreciate that the features recited in the various embodiments of the disclosure and/or in the claims may be provided in a variety of combinations and/or combinations, even if such combinations or combinations are not explicitly recited in the disclosure. In particular, the features recited in the various embodiments of the present disclosure and/or the claims may be variously combined and/or combined without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of the present disclosure.
While the present disclosure has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. The scope of the disclosure should, therefore, not be limited to the above-described embodiments, but should be determined not only by the following claims, but also by the equivalents of the following claims.
Claims (10)
1. A miniaturized ion accelerator for medical use, comprising:
an ion source (1) for generating low energy ions having an initial energy;
a linear accelerator (2) for primarily accelerating the low-energy ions to obtain a medium-energy beam;
a synchrotron (3) for accelerating the medium energy beam to obtain a high energy beam of target energy;
the synchrotron (3) comprises:
the two deflection units (4) are connected end to end through two straight sections and are used for deflecting the beam in the synchronous accelerator (3), and the deflection angle of each deflection unit (4) is 180 degrees;
the two focusing units are in one-to-one correspondence with the straight line sections and are arranged on the straight line sections and used for focusing the beam current in the synchrotron (3) in the horizontal direction and the vertical direction;
the high-frequency accelerating cavity (5) is arranged on one straight section and is used for accelerating the beam current in the synchronous accelerator (3);
the injection system is arranged on the two straight sections and is used for introducing medium energy beam current into the synchrotron (3);
and the slow extraction system is arranged on the two straight sections and is used for extracting high-energy beam current of target energy obtained after acceleration.
2. The miniaturized medical ion accelerator according to claim 1, characterized in that a stripping film (6) is mounted between the linac (2) and the synchrotron (3) for converting ions in the medium energy beam into ions required for treatment.
3. The miniaturized medical ion accelerator of claim 1, wherein the implantation system is configured for multi-turn implantation, the implantation system comprising:
an injection cutting magnet (7) for injecting the medium energy beam into the synchrotron (3);
the injection convex rail magnets (9) are respectively arranged on the two straight line sections and are used for forming local convex rails with gradually reduced heights, and the horizontal acceptance of the synchronous accelerator (3) is adjusted to the position of the outlet of the injection static deflection plate (8);
the injection static deflection plate (8) is arranged on one of the two straight sections, is connected with the injection cutting magnet (7), and is used for giving a transverse kicking angle to the medium energy beam so that the medium energy beam enters the horizontal receiving degree of the synchronous accelerator (3) and gradually fills the whole horizontal receiving degree along with the descent of the convex rail.
4. The medical miniaturized ion accelerator of claim 1, wherein the slow extraction system comprises:
the outgoing electrostatic deflection plate (10) and the outgoing cutting magnet (11) are respectively arranged on the two straight sections and adjacent to the focusing unit, and the phase shift of the outgoing electrostatic deflection plate (10) and the outgoing cutting magnet (11) is 270 degrees and is used for outgoing high-energy beam current of target energy obtained after acceleration.
5. The miniaturized medical ion accelerator according to claim 1, characterized in that each focusing unit comprises three quadrupole magnets (13).
6. The medical miniaturized ion accelerator of claim 5, wherein the slow extraction system comprises:
and the plurality of extraction convex rail magnets (14) are respectively arranged on the two straight line sections and are used for forming local convex rails at the extraction static deflection plates (10) so that the beam current in the synchrotron (3) approaches to the polar plates of the extraction static deflection plates (10).
7. The medical miniaturized ion accelerator of claim 6, wherein the slow extraction system further comprises:
two resonating hexapole irons (15) symmetrically arranged on the two straight line sections and adjacent to the quadrupole magnets (13) at one end of the focusing unit on the corresponding straight line section, and are used for inducing beam third-order resonance in the synchrotron (3) and forming a stable triangle in a phase space;
two chromaticity correction hexapole irons (16) are symmetrically arranged on the two straight line sections and are adjacent to a quadrupole magnet (13) at the other end of the focusing unit on the corresponding straight line section, and the two chromaticity correction hexapole irons are used for adjusting chromaticity to enable particle extraction phase diagrams with different energies in beam current in the synchronous accelerator (3) to overlap, so that extraction efficiency is improved;
and the extraction excitation (12) is arranged on one section of the straight line section and is used for generating a transverse high-frequency electric field to enable the amplitude of the particle motion to be larger, gradually leaves the stable triangle and is extracted.
8. The miniaturized medical ion accelerator according to claim 1, characterized in that each deflection unit (4) is composed of a plurality of superconducting secondary magnets.
9. The medical miniaturized ion accelerator according to claim 1, characterized in that the ion source (1) is an electron cyclotron resonance ion source.
10. The medical miniaturized ion accelerator according to claim 1, characterized in that the linac (2) comprises:
a radio frequency quadrupole field accelerator for accelerating low energy ions extracted from the ion source (1) to an energy level of 0.6 MeV/u;
and the drift tube linear accelerator is used for accelerating the low-energy ions accelerated by the radio-frequency quadrupole field accelerator to an energy level of 4-7 MeV/u.
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