Multi-energy multi-ion linear accelerator for isotope production

Abstract

The invention provides a multi-energy multi-ion linear accelerator for isotope production. The multi-energy multi-ion linear accelerator comprises an ion source system located on a main path of a beam, a radio frequency quadrupole accelerator and a multi-section drift tube linear acceleration unit, the ion source system comprises a plurality of ion sources, deflection magnets are arranged between two adjacent sections of the drift tube linear acceleration unit and on the downstream of the last section, and the deflection magnets can be switched between an opening state and a closing state and are used for enabling beam current to deflect to a sub-path of the beam current in the opening state and enabling the beam current to deflect to a sub-path of the beam current in the closing state. Therefore, each deflection magnet serves as a beam extraction position when being opened, and extraction of beams with different energies is realized. The multi-energy multi-ion linear accelerator for isotope production can output ion beams with different energies through different beam extraction positions, and accelerated ions can be protons, deuterium ions, helium ions, carbon ions, nitrogen ions, oxygen ions and other ions. Therefore, isotope production types are enriched, and isotope production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of charged particle accelerators, and particularly relates to a multi-energy multi-ion linear accelerator for isotope production. BACKGROUND

[0002] The basic principle of isotope production is to use particle beams to bombard target materials to produce nuclear reactions, so as to produce target elements, and then to obtain target elements with high purity through separation and purification processes.

[0003] At present, the production of isotopes mainly relies on nuclear reactors and cyclotrons.

[0004] The nuclear waste produced by the nuclear reactor contains a large number of different elements, and the required part can be separated, or the target material can be bombarded by neutrons in the nuclear reactor to produce the corresponding isotopes, and then obtained by separation. The advantage is that as a byproduct or additional facility of the nuclear reactor, the construction cost is relatively low, and the disadvantage is that the types of isotopes that can be produced are very limited and cannot meet the broad demand.

[0005] The cyclotron produces isotopes by accelerating protons to target, and then obtains them by separation. The advantage is that the cyclotron technology is mature, the construction cost is low, and the types of isotopes that can be produced are relatively rich. The disadvantage is that the beam intensity that can be accelerated is low, with a maximum of hundreds of microamperes, and the efficiency of isotope production is limited, which is difficult to meet the broad demand.

[0006] At present, the existing linear accelerators in the world are mostly designed for single particles (such as protons or heavy ions), and the linear accelerators are designed as injectors of other accelerators, with low output energy, which cannot meet the demand of isotope production.

[0007] Therefore, it is necessary to provide a linear accelerator for isotope production to improve the efficiency of isotope production. SUMMARY

[0008] The purpose of the present application is to provide a multi-energy multi-ion linear accelerator for isotope production to enrich the types of isotope production and improve the efficiency of isotope production.

[0009] In order to achieve the above purpose, the present application provides a multi-energy multi-ion linear accelerator for isotope production, comprising an ion source system, a radio frequency quadrupole accelerator, and a multi-section drift tube linear acceleration unit located on the main path of the beam; the ion source system comprises a plurality of ion sources, and a deflection magnet is arranged between adjacent two sections of the drift tube linear acceleration unit and downstream of the last section, and the deflection magnet is switchable between an open state and a closed state, for deflecting the beam to a sub-path of the beam when the open state is turned on, so that each deflection magnet acts as a beam extraction position when turned on, and the extraction of beams with different energies is realized.

[0010] Preferably, each drift tube linear acceleration unit is provided with a beam energy adjusting cavity at its last end, and the beam energy adjusting cavity continuously adjusts the energy gain value of the beam in the vicinity of its rated energy value.

[0011] Preferably, the beam energy adjusting cavity continuously adjusts the energy gain value of the beam in the vicinity of its rated energy value in a range of at least 1 MeV.

[0012] Preferably, the adjustment of the energy gain value of the beam energy adjusting cavity is realized by adjusting the microwave power and / or phase fed into the beam energy adjusting cavity.

[0013] Preferably, the rated energy gain values of the beams provided by different drift tube linear acceleration units are determined according to the energy requirements of isotope production, and each kind of ion has at least 5 rated energy points in the range of 8-30 MeV when being extracted.

[0014] Preferably, the ions produced by the ion source include at least two of protons (H + ), deuterium ions (D + ), helium ions (He 2+ ), carbon ions (C 6+ ), nitrogen ions (N 7+ ) and oxygen ions (O 8+ ).

[0015] Preferably, a detachable isotope production target is arranged on the sub-path of the beam downstream of each deflection magnet.

[0016] Preferably, a beam measurement device, the deflection magnet and a second matching section are sequentially arranged between adjacent two sections of the drift tube linear acceleration unit and downstream of the last section.

[0017] Preferably, the sub-path of the beam forms an angle with the main path of the beam, and the number of sub-paths of the beam corresponding to each deflection magnet can be 1 or 2.

[0018] Preferably, the ion source system comprises multiple ion sources, an ion source deflection magnet and an ion source matching section arranged in sequence along the propagation direction of the ion beam; and a buncher and a first matching section are arranged between the radio frequency quadrupole accelerator and the drift tube linear acceleration unit.

[0019] The multi-energy multi-ion linear accelerator for isotope production of the present application can accelerate particle flow with a strength of tens of milliamperes when used for isotope production, which is more than 100 times that of a cyclotron, and can greatly improve the efficiency of isotope production; and the device is more compact and occupies a smaller area.

[0020] The linear accelerator can output ion beam flows with different energies through different beam extraction positions, and the accelerated ions can be protons, deuterium ions, helium ions, carbon ions, nitrogen ions and oxygen ions and the like, aiming to provide beam flows for isotope production, thereby enriching isotope production types and improving isotope production efficiency. In addition, the beam energy of each beam extraction position can be adjusted within a certain range, thereby providing the required optimal conditions for various isotope production, reducing the difficulty of subsequent separation and purification, and improving isotope purity. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural schematic diagram of a multi-energy multi-ion linear accelerator for isotope production of the present application. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the following embodiments are only used to illustrate the present application and are not used to limit the scope of the present application.

[0023] The multi-energy multi-ion linear accelerator for isotope production of the present application comprises an ion source system 10, a radio frequency quadruple accelerator (RFQ) 20 and a multi-section drift tube linear acceleration unit (DTL) 30 located on the main path of the beam flow.

[0024] A buncher 41 and a first matching section 42 are arranged between the radio frequency quadruple accelerator 20 and the drift tube linear acceleration unit 30. The buncher 41 is used to realize the longitudinal matching of the beam flow from the radio frequency quadruple accelerator 20 to the drift tube linear acceleration unit 30. The phase space distribution of the beam flow at the outlet of the radio frequency quadruple accelerator 20 is opposite in the horizontal and vertical directions, which cannot meet the injection requirements of the drift tube linear acceleration unit 30, so the beam flow parameter matching between the upstream and downstream different acceleration structures is realized through the first matching section 42, so that the beam flow parameter output by the upstream can be within the acceptance range of the downstream structure. The first matching section 42 is preferably composed of three four-stage magnets. After passing through the matching section composed of three electromagnetic quadrupole magnets, the phase space distribution of the beam flow becomes consistent, and the movement trend is focusing, thereby meeting the injection requirements of the drift tube linear acceleration unit 30.

[0025] A beam measurement device (not shown in the figure), a deflection magnet 52, and a second matching section 53 are sequentially arranged between adjacent sections of the drift tube linear acceleration unit 30 and downstream of the last section. The beam measurement device is used to monitor the changes of the beam parameters. The deflection magnet 52 is switchable between an open state and a closed state, and is used to deflect the beam to a sub-path of the beam in the open state, so that each deflection magnet 52 acts as a beam extraction position when it is open, thereby realizing the extraction of beams of different energies. The second matching section 53 not only enables the matching of the beam parameters between the upstream and downstream acceleration structures, so that the beam parameters output by the upstream can be within the acceptance range of the downstream structure, but also enables the lossless transmission of the beam when part of the drift tube linear acceleration unit 30 is closed. The second matching section 53 preferably adopts three four-stage magnets. In other embodiments, the beam measurement device and the second matching section 53 can be replaced or omitted. In the present embodiment, the structure in the dashed box in the figure (i.e., the drift tube linear acceleration unit 30 and the corresponding beam measurement device, deflection magnet 52, and second matching section 53) is the basic periodic structure, the deflection magnet 52 at the tail end of each period is the beam extraction point, and the linear accelerator can be further extended by adding the basic periodic structure, the number of basic periodic structures is determined according to the requirements, and the highest energy can reach 100 MeV / u.

[0026] An isotope production target 60 is arranged on the sub-path of the beam downstream of each deflection magnet 52, thereby realizing isotope production. In the present embodiment, a third matching section 61 is further arranged on the sub-path of the beam between each deflection magnet 52 and the isotope production target 60, so that the beam parameters output by the upstream can be within the acceptance range of the downstream structure. The third matching section 61 preferably adopts three four-stage magnets.

[0027] In the present embodiment, the sub-path of the beam is perpendicular to the main path of the beam, and the number of sub-paths of the beam corresponding to each deflection magnet 52 is 2, and the directions of the two sub-paths are opposite. In other embodiments, the sub-path of the beam forms an angle with the main path of the beam (i.e., not necessarily perpendicular), and the number of sub-paths of the beam corresponding to each deflection magnet 52 can be 1 or 2.

[0028] The ion source system 10 is used to generate an ion beam and includes multiple ion sources. In the present embodiment, the ion source system 10 includes multiple ion sources 11, an ion source deflection magnet 12, and an ion source matching section arranged in sequence along the propagation direction of the ion beam. The ion source deflection magnet 12 and the ion source matching section constitute a low-energy transmission line of the ion source 11.

[0029] The number of ion sources 11 is multiple, which are used to generate different ions to realize the rapid switching of different ions without stopping the accelerator. The ions produced by the ion source 11 include but are not limited to protons (H + ), deuterium ions (D +He 2 + C 6+ N 7+ O 8+ at least two of the following: H

[0030] The ion source 11 is preferably an Electron Cyclotron Resonance (ECR) ion source. The ion source 11 is fed with different kinds of gas (such as H2, D2, He, CO2, N2, O2, etc.) and microwave power is fed into the ion source 11. The gas is ionized to form plasma in the discharge chamber, and the corresponding ions (such as H D + He 2+ C 6+ N 7+ O 8+ , etc.) are generated by ionization. The ions are extracted by an extraction high voltage to provide a sufficient ion beam current for the accelerator. In the embodiment, the number of ion sources 11 is two. The ion source can generate many kinds of ions by changing the type of gas fed into the ion source. However, considering the time required to switch the gas, the complexity of the mechanical structure required to quickly switch the gas, the preheating time required for the ion source to enter a stable working state, and other factors, it is difficult for one ion source to achieve rapid switching of multiple ions without stopping the accelerator.

[0031] The number of ion source matching sections is one, which can include a quadrupole magnet 131 and a solenoid 132. The quadrupole magnet 131 and the solenoid 132 are respectively used for focusing and transmitting the beam, so that the beam can be injected into the radio frequency quadrupole accelerator 20 with parameters meeting the acceptance requirements of the entrance of the radio frequency quadrupole accelerator 20. The ion source deflection magnet 12 is used to transmit the ions generated by the multiple ion sources 11 into the same ion source matching section.

[0032] The radio frequency quadrupole accelerator (RFQ) 20 includes a radial matching section, a shaping section, a bunching section, and an acceleration section. Thus, the beam is in a continuous beam state when it leaves the ion source system 10, first enters the radial matching section of the RFQ, where the aperture of the accelerator is rapidly reduced, and the transverse shape of the beam is modulated to enter the acceptance range. In the shaping section, the modulation of the pole tip starts from 0 and slowly increases, and the continuous beam also starts to slowly bunch into a beam bunch. In the bunching section, the modulation of the pole tip is further increased to a maximum value, and the beam is further bunched, and the transverse and longitudinal phase space distributions of the beam are both periodically oscillating. Finally, the beam enters the acceleration section, where the pole tip basically remains at the maximum modulation, and is mainly used for accelerating the beam. The beam is accelerated to above 1.5 MeV / u by the RFQ.

[0033] The radio frequency quadrupole accelerator 20 is preferably a four-wing radio frequency quadrupole accelerator. The radio frequency quadrupole accelerator is an accelerating structure invented for the characteristics of the low-energy proton beam, mainly generates strong focusing effect by four electrodes, solves the problem of the increase of the emittance of the low-energy proton beam, and adds modulation on the pole head to generate accelerating effect. Compared with other types of radio frequency quadrupole accelerators, the four-wing radio frequency quadrupole accelerator has strong heat dissipation capacity and can improve the duty ratio during operation. In the present application, the radio frequency quadrupole accelerator can operate at a duty ratio of 100%. The radio frequency quadrupole accelerator can accelerate ions to a certain energy.

[0034] The drift tube linear acceleration unit 30 is a structure formed by installing a drift tube in a radio frequency cavity and used for continuing to accelerate ions. In the present embodiment, the drift tube linear acceleration unit 30 adopts an interdigital H-mode drifting tube linac (IH-DTL).

[0035] Different drift tube linear acceleration units 30 have different rated energy gain values, so that the energy gain values of different drift tube linear acceleration units 30 are different for the same ions. In the present embodiment, the rated energy gain values provided by different drift tube linear acceleration units 30 to the beam are determined according to the energy requirements of isotope production. Each type of ion has at least five rated energy points in the range of 8-30 MeV when the beam is extracted, so that the beam energy at different beam extraction positions respectively meets the energy requirements of different types of isotope production. The energy requirements of isotope production may, for example, be the required beam energy value of the isotope during production.

[0036] Each type of ion has rated energy points corresponding to the switch state combinations of all the upstream drift tube linear acceleration units 30 at each beam extraction position, so that the ions are output at the rated energy points without fine tuning at each beam extraction position. That is, after the rated energy gain values of different drift tube linear acceleration units 30 are determined, when the highest energy of the linear accelerator of the present application is required, all the drift tube linear acceleration units 30 work; when other target rated energy points are required, one or several sections of drift tube linear acceleration units 30 can be sequentially turned off from the downstream, and the beam is only accelerated to the target rated energy point, or the upstream deflection magnet is directly used to extract the beam, so that the energy of the beam extracted at the beam extraction position is the target rated energy point. In this way, the demand of multiple isotope production can be met. Thus, the multi-energy ion linear accelerator of the present application can greatly improve the production efficiency and production types of isotopes, reduce the difficulty of isotope separation and purification, and improve the purity of isotopes by switching on and off the multiple sections of drift tube linear acceleration units 30 and extracting the beam at multiple beam extraction positions.

[0037] The RF quadrupole accelerator 20 and the drift tube linac unit 30 both use a klystron as a power source, and feed power to the accelerating cavities of the RF quadrupole accelerator 20 and the drift tube linac unit 30 through a magnetic type coupler. Thus, RF power is generated from the power source, transmitted through a coaxial cable to the coupler, and then excited by the loop probe of the magnetic type coupler to generate electromagnetic fields in the accelerating cavities.

[0038] Each drift tube linac unit 30 is provided with a beam energy adjustment cavity 31 at the end thereof, thereby forming two sections. The beam energy adjustment cavity 31 provides a continuous adjustable energy gain value to the beam in the vicinity of the rated energy value. In the present embodiment, the beam energy adjustment cavity 31 provides a continuous adjustable energy gain value to the beam in the vicinity of the rated energy value in a range of at least 1 MeV, thereby providing the required optimum conditions for the production of various isotopes, reducing the difficulty of subsequent separation and purification, and improving the purity of isotopes.

[0039] The beam energy adjustment cavity 31 is structurally consistent with the accelerating components of the drift tube linac unit, except that it is designed and optimized for energy adjustment from the perspective of beam physics, to ensure that it has a high beam quality when extracted at different energy values. The adjustment of the energy gain value of the beam energy adjustment cavity 31 can be achieved by adjusting the microwave power and / or phase fed into the beam energy adjustment cavity 31. However, by adjusting the power and / or phase of the fed-in microwave, the original beam dynamics will be changed, resulting in consequences such as beam defocusing and increased energy spread, further leading to beam loss. Beam loss will increase the risk of structure activation and the difficulty of radiation protection, and may also affect the service life of the device. Therefore, the beam energy adjustment cavity 31 needs to be optimized.

[0040] For the beam energy adjustment cavity 31, energy adjustment is mainly related to energy gain, and the energy gain of the accelerator can be expressed as q is the ion charge, which cannot be changed; V is the accelerating voltage, and the present patent refers to changing the microwave power, i.e. changing the accelerating voltage; is the synchronous phase, i.e. the microwave phase in which the ions are located, and the present patent refers to changing the microwave phase, i.e. changing the synchronous phase. Energy adjustment can be achieved by changing the microwave power and phase in the above-mentioned manner.

[0041] Energy adjustment will largely result in a decrease in beam quality, causing a large amount of beam loss, so that energy adjustment will also lose its significance. Therefore, the optimization goal of the beam energy adjustment cavity 31 is to ensure sufficient beam quality (i.e. the beam quality is greater than a quality threshold value within the energy adjustment range) by optimizing the cavity length and the rated synchronous phase, so that the beam is not lost in large quantities.

[0042] The drift tube linear acceleration unit 30 is designed to match the structure and particle beam speed, and multiple energy extraction can be achieved by reasonable design as described above; at the same time, the design of the application can adjust the microwave power and phase of the drift tube linear acceleration unit 30, slightly mismatch the structure design of the drift tube linear acceleration unit 30 with the beam energy, change the beam dynamics, achieve the change within a certain range near the above-mentioned multiple energy points, and the design theory can realize the continuous adjustment of the beam energy.

[0043] Therefore, the multi-energy multi-ion linear accelerator for isotope production of the application can compensate for the beam parameters by adjusting the energy gain value of the beam energy adjustment cavity 31 and the real-time measurement results of the beam measurement device and the target energy when the device parameters change. In addition, experiments can also be carried out by the multi-energy multi-ion linear accelerator of the application, and specific target materials are placed downstream of different beam extraction positions at the same time, and through the combination of different rated energy points and energy fine tuning, the optimal isotope production method for specific target materials is quickly found, and the optimal parameter setting is automatically recorded by the beam measurement device.

[0044] In this embodiment, when the beam energy is fine tuned each time, only the beam energy adjustment cavity 31 in the drift tube linear acceleration unit 30 at the lowermost downstream in the working state is adjusted to avoid the slight mismatch affecting the work of the drift tube linear acceleration unit 30 downstream of the beam energy adjustment cavity 31.

[0045] The working principle of the multi-energy multi-ion linear accelerator for isotope production of the application is specifically described below with an example.

[0046] Different kinds of gases (H2, D2, He, CO2, N2, O2) are introduced into the ion source, and microwave power is fed in. The gas will form plasma in the discharge chamber to produce corresponding ions ( D + , He 2+ , C 6+ , N 7+ , O 8+ ), and the high voltage is 35kV, that is, the ion extraction energy is 35keV / u. After the beam passes through the ion source deflection magnet 12, transmission and focusing in the ion source matching section, it enters the radio frequency quadrupole accelerator 20.

[0047] The radio frequency quadrupole accelerator 20 accelerates the beam from 35keV / u to 1.5MeV / u, and after being bunched by the buncher 41 and adjusting the parameters in the first matching section 42, it enters the drift tube linear acceleration unit 30.

[0048] In the embodiment, the number of the drift tube linear acceleration units 30 is 7 sections, and the designed extraction energy points are 8 / 12 / 17 / 23 / 30 MeV / u, which respectively correspond to the 3rd-7th drift tube linear acceleration units 30. When the energy of 8 MeV / u is needed, the first three drift tube linear acceleration units 30 are allowed to work; when the energy of 22 MeV / u is needed, the first six drift tube linear acceleration units 30 are allowed to work, and meanwhile, the microwave power and phase fed into the beam energy adjusting cavity 31 of the 6th drift tube linear acceleration unit 30 are adjusted, so that the output beam energy is reduced by 1 MeV / u to reach the target energy.

[0049] The multi-energy multi-ion linear accelerator for isotope production can accelerate particle flow with a strength of tens of milliamperes, and the duty cycle can reach 100% when working, which is beneficial to improving the isotope production efficiency, is more than 100 times of the cyclotron, and can greatly improve the isotope production efficiency; and the occupied area is small, and the device is more compact.

[0050] In addition, according to the specific conditions of the target elements and impurities generated by the nuclear reaction of different particles with different target materials at different energies, the optimal particles and their energies required for producing different target elements are also different. In order to achieve the best production effect, the linear accelerator provided by the present application can output ion beams of different energies through different beam extraction positions, and the accelerated ions can be protons, deuterium ions, helium ions, carbon ions, nitrogen ions and oxygen ions and the like. The linear accelerator is designed to provide beam for isotope production, optimize the existing isotope production device and improve the production efficiency. Furthermore, a plurality of ions including but not limited to protons, deuterium ions and helium ions can be accelerated to a highest energy of more than 30 MeV, and through reasonable segmentation and design optimization, the beam energy of each ion at the extraction position has more than six energy points in the range of 8-30 MeV, and the beam energy of each beam extraction position can be adjusted within a certain range, thereby providing the required optimal conditions for the production of a plurality of isotopes, reducing the difficulty of subsequent separation and purification, and improving the isotope purity. The design of multi-energy and multi-ion can meet the needs of most isotope production devices.

[0051] The above is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application. The above embodiment of the present application can be variously changed. Any simple, equivalent changes and modifications made in accordance with the content of the claims and description of the present application fall within the scope of the claims of the present patent. The present application is not described in detail.

Claims

1. A multi-energy, multi-ion linear accelerator for isotope production, characterized in that, The system includes an ion source system located on the main path of the beam, a radio frequency quadrupole accelerator, and a multi-segment drift tube linear acceleration unit. The ion source system includes multiple ion sources. Deflection magnets are provided between adjacent segments and downstream of the last segment of the drift tube linear acceleration unit. The deflection magnets can be switched between on and off states. When on, they are used to deflect the beam to a sub-path of the beam, so that each deflection magnet serves as a beam extraction position when on, thereby enabling the extraction of beams with different energies.

2. The multi-energy multi-ion linear accelerator for isotope production according to claim 1, characterized in that, Each drift tube linear acceleration unit has a beam energy adjustment cavity at its very end. The energy gain value provided by the beam energy adjustment cavity to the beam is continuously adjustable near its rated energy value.

3. The multi-energy multi-ion linear accelerator for isotope production according to claim 2, characterized in that, The energy gain provided by the beam energy conditioning cavity to the beam is continuously adjustable within a range of at least 1 MeV near its rated energy value.

4. The multi-energy multi-ion linear accelerator for isotope production according to claim 2, characterized in that, The energy gain value of the beam energy conditioning cavity is adjusted by adjusting the microwave power and / or phase fed into the beam energy conditioning cavity.

5. The multi-energy multi-ion linear accelerator for isotope production according to claim 1, characterized in that, The rated energy gain provided by different drift tube linear acceleration units to the beam is determined according to the energy requirements of isotope preparation. Each ion has at least 5 rated energy points in the range of 8-30 MeV when it is extracted.

6. The multi-energy multi-ion linear accelerator for isotope production according to claim 1, characterized in that, The ions produced by the ion source include protons (H). + Deuterium ion D + Helium ions (He) 2+ Carbon ions (C) 6+ Nitrogen ions N 7+ and oxygen ions O 8+ At least two of them.

7. The multi-energy multi-ion linear accelerator for isotope production according to claim 1, characterized in that, Each deflector magnet has a detachable isotope production target on a sub-path of the beam downstream of it.

8. The multi-energy multi-ion linear accelerator for isotope production according to claim 1, characterized in that, A beam measuring device, the deflection magnet, and a second matching section are sequentially installed between adjacent sections and downstream of the last section of the drift tube linear acceleration unit.

9. The multi-energy multi-ion linear accelerator for isotope production according to claim 1, characterized in that, The sub-path of the beam forms an angle with the main path of the beam, and the number of sub-paths of the beam corresponding to each deflecting magnet is one or two.

10. The multi-energy multi-ion linear accelerator for isotope production according to claim 1, characterized in that, The ion source system includes multiple ion sources, ion source deflection magnets, and ion source matching sections arranged sequentially along the propagation direction of the ion beam; a beam gatherer and a first matching section are provided between the radio frequency quadrupole accelerator and the drift tube linear acceleration unit.

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