阅读说明：本技术 一种无液氦射频超导加速器 (Liquid helium-free radio frequency superconducting accelerator ) 是由 杨自钦 何源 蒋天才 白峰 王志军 郭浩 徐孟鑫 张升学 刘鲁北 陈伟龙 皇世春 于 2021-08-05 设计创作，主要内容包括：本发明涉及一种无液氦射频超导加速器,其带电粒子束流经注入系统产生和引出,经束流传输系统被引入到加速模组,功率源系统向加速模组提供射频功率,低电平与控制系统监测运行、维持超导腔内的电磁场幅度和相位稳定,带电粒子在加速模组内得到加速后,再经束流传输系统被引入应用终端。本发明通过固体传导的方式对超导腔进行冷却,使超导腔在低温下稳定运行,加速带电粒子束流,摆脱当前射频超导加速腔只能浸泡在液氦里的冷却方式,省去结构复杂的液氦浸泡冷却恒温器和造价昂贵占地规模大的液氦低温站,价格便宜、占地面积小、结构简单、布局紧凑、运维方便等优点,能够显著降低射频超导加速器的应用难度,大大拓展射频超导加速器的应用范围。(The invention relates to a liquid-helium-free radio frequency superconducting accelerator, wherein charged particle beams are generated and led out through an injection system and are led into an acceleration module through a beam transmission system, a power source system provides radio frequency power for the acceleration module, a low level and control system monitors operation and maintains the amplitude and phase stability of an electromagnetic field in a superconducting cavity, and the charged particles are accelerated in the acceleration module and then are led into an application terminal through the beam transmission system. The superconducting cavity is cooled in a solid conduction mode, so that the superconducting cavity stably operates at a low temperature, charged particle beams are accelerated, the cooling mode that the radio-frequency superconducting accelerating cavity can only be soaked in liquid helium at present is eliminated, a liquid helium soaking cooling thermostat with a complex structure and a liquid helium low-temperature station with high manufacturing cost and large occupied area are omitted, and the radio-frequency superconducting accelerator has the advantages of low price, small occupied area, simple structure, compact layout, convenience in operation and maintenance and the like, can obviously reduce the application difficulty of the radio-frequency superconducting accelerator, and greatly expands the application range of the radio-frequency superconducting accelerator.)

1. A liquid helium-free radio frequency superconducting accelerator is characterized by comprising a charged particle injection system (10), a beam transmission system (20), an acceleration module system (30), a power source system (40), a low level and control system (50) and an application terminal (60);

the input end and the output end of the acceleration module system (30) are respectively connected with the output end of the charged particle injection system (10) and the input end of the application terminal (60) through the beam transmission system (20);

the charged particle injection system (10) is configured to generate a charged particle beam of a specific energy, a specific species, a specific fluence, specific parameters;

the beam delivery system (20) is configured to direct a charged particle beam exiting from the charged particle injection system (10) to enter a superconducting cavity of the acceleration module system (30) to be accelerated, and to direct the accelerated charged particle beam exiting from the superconducting cavity of the acceleration module system (30) to be delivered to the application terminal (60) according to a specified trajectory;

the power source system (40) is connected with the superconducting cavity of the acceleration module system (30), and the power source system (40) is configured to provide radio-frequency power to the superconducting cavity of the acceleration module system (30) to establish a radio-frequency electromagnetic field in the superconducting cavity, so that the beam of charged particles is accelerated by the action of the electromagnetic field in the superconducting cavity;

the low level and control system (50) is respectively electrically connected with the charged particle injection system (10), the beam transmission system (20), the acceleration module system (30) and the application terminal (60), and the low level and control system (50) is configured to monitor the running state of the accelerator by acquiring and processing temperature, vacuum degree, radio frequency, beam position, beam energy and beam emittance signals of the accelerator, and maintain the amplitude and phase stability of an electromagnetic field in the superconducting cavity.

2. The liquid helium-free radio frequency superconducting accelerator according to claim 1, wherein the acceleration module system (30) comprises:

a superconducting cavity (1) configured to provide energy to a beam of charged particles;

a cryogenic unit (2) configured to provide a required cryogenic environment to the superconducting cavity (1);

a vacuum unit (3) connected to the superconducting cavity (1), the vacuum unit (3) being configured to provide a cavity vacuum environment and an interlayer vacuum environment required for operation to the superconducting cavity (1).

3. The hHe-free RF superconducting accelerator according to claim 2, wherein the power source system (40) comprises a power source and a coupler (4), the coupler (4) being connected to a coupling port of the superconducting cavity (1), the coupler (4) being configured to feed RF power output by the power source into the superconducting cavity (1).

4. The liquid-helium-free radio frequency superconducting accelerator according to claim 2, wherein the beam transport system (20) comprises a beam pipeline, a magnet element and a beam diagnosis element, the beam pipeline is machined from stainless steel and is butted with a pipeline of the acceleration module system (30), the beam pipeline is vacuumized, the vacuum degree is lower than 1e-5Pa, and the joint of the beam pipeline is completely sealed by metal to ensure high vacuum; the beam pipeline is provided with beam diagnostic elements for measuring the position, energy, intensity and emittance of the charged particle beam, and the beam pipeline is also provided with a dipolar magnet for deflecting the charged particle beam, and/or a solenoid and a quadrupole magnet for focusing the charged particle beam, and/or a hexapole magnet for eliminating dispersion, and/or a scanning magnet for irradiation.

5. The liquid helium-free radio frequency superconducting accelerator according to claim 1, wherein the charged particles generated by the charged particle injection system (10) comprise electrons, protons, or carbon ions.

6. The liquid helium-free radio frequency superconducting accelerator according to claim 1, wherein the cryogenic unit (2) comprises:

a cold shield (2-1) housed outside the superconducting cavity (1), the cold shield (2-1) being configured to reduce static heat loss of the superconducting cavity (1);

a magnetic shielding layer arranged in the space between the cold shield (2-1) and the superconducting cavity (1), said magnetic shielding layer being configured to shield the earth's ambient magnetic field, reducing the magnetic flux capture of the superconducting cavity (1);

the multiple groups of cold guide blocks (2-2) are arranged in the heating area of the superconducting cavity (1), and the inner surface of each cold guide block (2-2) is attached to the outer surface of the superconducting cavity (1);

the secondary cold plates (2-3) are arranged above the cold guide blocks (2-2), and one sides of the secondary cold plates (2-3) are respectively connected with the multiple groups of cold guide blocks (2-2) through flexible cold chains (2-4);

and at least one refrigerating machine (2-5) is arranged above the secondary cold plate (2-3), and a secondary cold head (2-6) of the refrigerating machine (2-5) is connected with the other side of the secondary cold plate (2-3) through a flexible cold chain (2-4).

7. The liquid helium-free radio frequency superconducting accelerator according to claim 6, wherein the cold guide blocks (2-2) are in a half-and-half hoop form, and the half-and-half hoops of the cold guide blocks (2-2) are fastened and connected through screws and nuts;

meanwhile, indium sheets are uniformly arranged on the contact interface of the cold guide block (2-2) and the superconducting cavity (1) and the connection part of the half-and-half hoops;

temperature sensors are respectively arranged on the outer surface of a heating area of the superconducting cavity (1), the cold conducting block (2-2), the secondary cold plate (2-3) and the secondary cold head (2-6) and are used for monitoring the temperature change of the superconducting cavity (1);

meanwhile, a high-precision heater is arranged on the secondary cold head (2-6) and is used for being matched with a temperature controller and a temperature sensor, so that the condition that the cooling rate is stable between 30K and 15K and is continuously adjustable between 1min/K and 5min/K is realized, and the temperature gradient of the superconducting cavity (1) in the axial direction is ensured to be less than or equal to 0.025K/cm;

a fluxgate probe is arranged on the outer surface of the superconducting cavity (1), and the fluxgate probe is required to be capable of accurately measuring the magnetic field intensity less than or equal to 10mGs for residual magnetism measurement and monitoring.

8. The hHe-free RF superconducting accelerator according to claim 7, wherein the vacuum unit (3) comprises:

a vacuum enclosure (3-1) arranged outside the cold shield (2-1), the vacuum enclosure (3-1) being configured to form a sandwich vacuum environment for reducing static heat loss between the vacuum enclosure (3-1) and the superconducting cavity (1);

one end of each of the two groups of vacuum pipelines (3-2) is respectively connected with the two flow pipelines of the superconducting cavity (1) through a vacuum angle valve (3-3), and the other end of each of the two groups of vacuum pipelines (3-2) penetrates out of the vacuum cover (3-1) and then is connected with a vacuum pump set, so that a cavity vacuum environment for accelerating charged particles is formed in a superconducting cavity-pipeline system formed by the superconducting cavity (1) and the vacuum pipelines (3-2).

9. The hHe-free RF superconducting accelerator according to claim 8, wherein the vacuum enclosure (3-1) is made of stainless steel, and the inner and outer surfaces are polished; the top of the vacuum cover (3-1) is provided with a butt joint of the refrigerator (2-5), the side is provided with a butt joint of the vacuum pipeline (3-2), and the bottom is provided with a butt joint of the coupler (4); a temperature sensor wall penetrating piece (3-4) is reserved on the vacuum cover (3-1) and is used for butt joint of a data line of the temperature sensor; a magnetic probe sensor wall penetrating piece (3-5) is reserved on the vacuum cover (3-1) and is used for butt joint of data lines of the fluxgate probe; and a backfill port is reserved in the vacuum cover (3-1) and is used for high-purity nitrogen inflation recovery vacuum and pipeline cleaning.

10. The liquid helium-free radio frequency superconducting accelerator according to claim 8, further comprising a damper (5) disposed on top of the vacuum enclosure (3-1), the refrigerator (2-5) being disposed on the damper (5);

meanwhile, the vibration of the refrigerating machine (2-5) is effectively prevented from being transmitted to the superconducting cavity (1) through a flexible cold chain (2-4) between a secondary cold head (2-6) of the refrigerating machine (2-5) and the superconducting cavity (1);

the superconducting cavity (1) is supported in the vacuum cover (3-1) through a supporting structure (6) made of nonmagnetic materials, and a fine adjustment rod is arranged on the supporting structure (6).

Technical Field

The invention relates to a superconducting accelerator, in particular to a liquid helium-free radio frequency superconducting accelerator based on solid conduction cooling, and belongs to the technical field of superconduction.

Background

The charged particle accelerator is an indispensable research means in the fields of high-energy physics, atomic molecular physics, life and material science, nuclear physics, radionuclide research and the like. Due to the extremely low surface resistance of a radio frequency superconducting accelerating cavity (superconducting cavity), compared with a normal temperature accelerator, the superconducting accelerator has the advantage of being capable of working in a high duty ratio or even a continuous wave mode, and radio frequency superconducting is one of core technologies of modern particle accelerators.

The superconducting cavity is the core accelerating component of the superconducting accelerator. At present, a superconducting cavity is mainly made of low-temperature superconducting material niobium, and needs to be soaked in liquid helium at the temperature of 2K-4K for cooling. However, the liquid helium immersion cooling mode causes a complex structure of a refrigeration system, is high in manufacturing cost, and requires a highly professional low-temperature refrigeration operation and maintenance team, which severely restricts the application range of the current superconducting accelerator taking a pure niobium superconducting cavity as a core. Therefore, how to get rid of the constraint of liquid helium is the key to reduce the complexity and the operation and maintenance difficulty of the superconducting accelerator and expand the application range of the superconducting accelerator.

On the one hand, has a high superconductive transition temperature (T)_c) And Nb with high over-heat magnetic field₃Sn、MgB₂Radio frequency performance of radio frequency superconducting materials such as NbN, NbTiN, iron-based superconductor and the like at 4.2K or even higher temperature can reach the level of a niobium-based superconducting cavity under 2K; on the other hand, the refrigerating power of the current industrial refrigerator at a low temperature of 4.2K reaches 2W, the refrigerating power of the current industrial refrigerator is increased along with the increase of the temperature, and the industrial refrigerator is driven by a cooling mode of solid conduction₃Sn、MgB₂The superconducting cavity of high-temperature superconducting materials such as NbN, NbTiN, iron-based superconductor and the like can stably work.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a solid conduction cooling-based liquid helium-free radio frequency superconducting accelerator, so as to get rid of the working mode that the conventional superconducting cavity must be immersed in liquid helium for cooling, and reduce the difficulty in applying the radio frequency superconducting technology.

In order to achieve the purpose, the invention adopts the following technical scheme: a liquid helium-free radio frequency superconducting accelerator comprises a charged particle injection system, a beam transmission system, an acceleration module system, a power source system, a low level and control system and an application terminal; the input end and the output end of the acceleration module system are respectively connected with the output end of the charged particle injection system and the input end of the application terminal through the beam transmission system; the charged particle injection system is configured to generate a charged particle beam of a specific energy, a specific species, a specific fluence, specific parameters; the beam delivery system is configured to guide the charged particle beam led out from the charged particle injection system to enter a superconducting cavity of the acceleration module system to be accelerated, and guide the accelerated charged particle beam led out from the superconducting cavity of the acceleration module system to be delivered to the application terminal according to a specified track; the power source system is connected with the superconducting cavity of the acceleration module system, and the power source system is configured to provide radio-frequency power to the superconducting cavity of the acceleration module system so as to establish a radio-frequency electromagnetic field in the superconducting cavity, so that the charged particle beam is accelerated in the superconducting cavity under the action of the electromagnetic field; the low level and control system is respectively electrically connected with the charged particle injection system, the beam transmission system, the acceleration module system and the application terminal, and is configured to monitor the running state of the accelerator by acquiring and processing the temperature, the vacuum degree, the radio frequency, the beam position, the beam energy and the beam emittance signal of the accelerator, and maintain the amplitude and the phase stability of the electromagnetic field in the superconducting cavity.

Preferably, the acceleration module system comprises: a superconducting cavity configured to energize a charged particle beam; a cryogenic unit configured to provide a desired cryogenic environment to the superconducting cavity; a vacuum unit connected to the superconducting cavity, the vacuum unit configured to provide a cavity vacuum environment and an interlayer vacuum environment required for operation to the superconducting cavity.

The liquid helium-free radio frequency superconducting accelerator preferably comprises a power source and a coupler, wherein the coupler is connected with a coupling port of the superconducting cavity, and the coupler is configured to feed radio frequency power output by the power source into the superconducting cavity.

The liquid helium-free radio frequency superconducting accelerator is characterized in that the beam transmission system preferably comprises a beam pipeline, a magnet element and a beam diagnosis element, the beam pipeline is processed by stainless steel and is butted with a pipeline of the acceleration module system, the beam pipeline is vacuumized, the vacuum degree is lower than 1e-5Pa, and the joints of the beam pipeline are all sealed by metal to ensure high vacuum; the beam pipeline is provided with beam diagnostic elements for measuring the position, energy, intensity and emittance of the charged particle beam, and the beam pipeline is also provided with a dipolar magnet for deflecting the charged particle beam, and/or a solenoid and a quadrupole magnet for focusing the charged particle beam, and/or a hexapole magnet for eliminating dispersion, and/or a scanning magnet for irradiation, and other magnet elements required according to application requirements.

In the liquid helium-free rf superconducting accelerator, preferably, the charged particles generated by the charged particle injection system include electrons, protons, carbon ions, or the like.

The liquid helium-free radio frequency superconducting accelerator preferably comprises the cryogenic unit and a control unit, wherein the cryogenic unit comprises: a cold shield disposed outside the superconducting cavity, the cold shield configured to reduce static heat loss from the superconducting cavity; a magnetic shielding layer disposed in a space between the cold shield and the superconducting cavity, the magnetic shielding layer configured to shield an earth ambient magnetic field, reducing magnetic flux capture by the superconducting cavity; the multiple groups of cold guide blocks are arranged in the heating area of the superconducting cavity, and the inner surface of each cold guide block is attached to the outer surface of the superconducting cavity; the secondary cold plate is arranged above the cold guide blocks, and one side of the secondary cold plate is respectively connected with the multiple groups of cold guide blocks through flexible cold chains; and at least one refrigerating machine is arranged above the secondary cold plate, and a secondary cold head of the refrigerating machine is connected with the other side of the secondary cold plate through a flexible cold chain.

Preferably, the cold guide block is in a half-and-half hoop form, and the half-and-half hoops of the cold guide block are fastened and connected through screws and nuts; meanwhile, indium sheets are uniformly arranged on the contact interface of the cold guide block and the superconducting cavity and the connection part of the half-and-half hoops; temperature sensors are arranged on the outer surface of the heating area of the superconducting cavity, the cold conducting block, the secondary cold plate and the secondary cold head and are used for monitoring the temperature change of the superconducting cavity; meanwhile, a high-precision heater is arranged on the secondary cold head and is used for being matched with a temperature controller and a temperature sensor, so that the conditions that the cooling rate is stable between 30K and 15K and is continuously adjustable between 1min/K and 5min/K are realized, and the temperature gradient of the superconducting cavity in the axial direction is ensured to be less than or equal to 0.025K/cm; and a fluxgate probe is arranged on the outer surface of the superconducting cavity, and the fluxgate probe is required to be capable of accurately measuring the magnetic field intensity less than or equal to 10mGs for residual magnetism measurement and monitoring.

The liquid helium-free radio frequency superconducting accelerator preferably comprises the vacuum unit: a vacuum enclosure disposed outside the cold shield, the vacuum enclosure configured to form an interlayer vacuum environment between the vacuum enclosure and the superconducting cavity for reducing static heat loss; and one ends of the two groups of vacuum pipelines are respectively connected with the two flow pipelines of the superconducting cavity through vacuum angle valves, and the other ends of the two groups of vacuum pipelines penetrate out of the vacuum cover and are connected with a vacuum pump set so as to form a cavity vacuum environment for accelerating charged particles in a superconducting cavity-pipeline system consisting of the superconducting cavity and the vacuum pipelines.

Preferably, the vacuum cover is made of stainless steel, and the inner surface and the outer surface of the vacuum cover are polished; the top of the vacuum cover is provided with a butt joint port of the refrigerator, the side of the vacuum cover is provided with a butt joint port of the vacuum pipeline, and the bottom of the vacuum cover is provided with a butt joint port of the coupler; a temperature sensor wall penetrating piece is reserved on the vacuum cover and is used for butt joint of data lines of the temperature sensor; a magnetic probe sensor wall penetrating piece is reserved on the vacuum cover and is used for butt joint of data lines of the fluxgate probe; and a backfill port is reserved in the vacuum cover and used for high-purity nitrogen inflation vacuum recovery and pipeline cleaning.

The liquid helium-free radio frequency superconducting accelerator preferably further comprises a shock absorber arranged at the top of the vacuum cover, and the refrigerator is arranged on the shock absorber; meanwhile, the vibration of the refrigerator is effectively prevented from being transmitted to the superconducting cavity through a flexible cold chain between a secondary cold head of the refrigerator and the superconducting cavity; the superconducting cavity is supported in the vacuum cover through a supporting structure made of nonmagnetic materials, and a fine adjustment rod is arranged on the supporting structure.

Due to the adoption of the technical scheme, the invention has the following advantages:

the charged particle beam is generated and led out through the injection system, and is led into the acceleration module through the beam transmission system, the power source system provides high-frequency power for the acceleration module, the low level and control system monitors operation and maintains the amplitude and phase stability of an electromagnetic field in a superconducting cavity, and the charged particle is accelerated in the acceleration module and then is led into an application terminal through the beam transmission system. The superconducting cavity is cooled in a solid conduction mode based on a commercial refrigerator, so that the superconducting cavity stably operates at low temperature, charged particle beams are accelerated, the current cooling mode that the radio frequency superconducting acceleration cavity can only be soaked in liquid helium is eliminated, a liquid helium soaking cooling thermostat with a complex structure and a liquid helium low-temperature station with high manufacturing cost and large occupied area are omitted, the radio frequency superconducting accelerator has the advantages of low price, small occupied area, simple structure, compact layout, convenience in operation and maintenance and the like, the application difficulty of the radio frequency superconducting accelerator can be remarkably reduced, and the application range of the radio frequency superconducting accelerator is greatly expanded.

Drawings

FIG. 1 is a schematic diagram of a liquid helium-free RF superconducting accelerator according to an embodiment of the present invention;

fig. 2 is an axial cross-sectional view of the acceleration module system according to the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the system or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used to define elements only for convenience in distinguishing between the elements, and unless otherwise stated have no special meaning and are not to be construed as indicating or implying any relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The invention provides a liquid-helium-free radio frequency superconducting accelerator which comprises a charged particle injection system, a beam transmission system, an acceleration module system, a power source system, a low level and control system and an application terminal; the input end and the output end of the acceleration module system are respectively connected with the output end of the charged particle injection system and the input end of the application terminal through a beam transmission system; the charged particle injection system is configured to generate a charged particle beam of a specific energy, a specific species, a specific fluence, specific parameters; the beam transmission system is configured to guide the charged particle beam led out from the charged particle injection system to enter a superconducting cavity of the acceleration module system to be accelerated, and guide the accelerated charged particle beam led out from the superconducting cavity of the acceleration module system to be transmitted to the application terminal according to a specified track; the power source system is connected with the superconducting cavity of the acceleration module system and is configured to provide radio-frequency power for the superconducting cavity of the acceleration module system so as to establish a radio-frequency electromagnetic field in the superconducting cavity, and the charged particle beam is accelerated under the action of the electromagnetic field in the superconducting cavity; the low level and control system are respectively electrically connected with the charged particle injection system, the beam transmission system, the acceleration module system and the application terminal, and the low level and control system is configured to monitor the running state of the accelerator by acquiring and processing the temperature, the vacuum degree, the radio frequency, the beam position, the beam energy and the beam emittance signal of the accelerator, and maintain the amplitude and the phase stability of an electromagnetic field in the superconducting cavity. The superconducting cavity is cooled in a solid conduction mode, so that the superconducting cavity stably operates at a low temperature, charged particle beams are accelerated, the cooling mode that the radio-frequency superconducting accelerating cavity can only be soaked in liquid helium at present is eliminated, a liquid helium soaking cooling thermostat with a complex structure and a liquid helium low-temperature station with high manufacturing cost and large occupied area are omitted, and the radio-frequency superconducting accelerator has the advantages of low price, small occupied area, simple structure, compact layout, convenience in operation and maintenance and the like, can obviously reduce the application difficulty of the radio-frequency superconducting accelerator, and greatly expands the application range of the radio-frequency superconducting accelerator.

The present invention provides a liquid-helium-free radio-frequency superconducting accelerator, which is described in detail below with reference to the accompanying drawings.

As shown in fig. 1, the liquid-helium-free rf superconducting accelerator provided in this embodiment includes a charged particle injection system 10, a beam transport system 20, an acceleration module system 30, a power source system 40, a low level and control system 50, and an application terminal 60. Wherein, the input end and the output end of the acceleration module system 30 are respectively connected with the output end of the charged particle injection system 10 and the input end of the application terminal 60 through the beam transmission system 20. The charged particle injection system 10 is configured to generate a charged particle beam with specific energy, specific species, specific flow intensity and specific parameters, and the beam transport system 20 is configured to guide the charged particle beam led out from the charged particle injection system 10 to enter the superconducting cavity of the acceleration module system 30 to be accelerated, and guide the accelerated charged particle beam led out from the superconducting cavity of the acceleration module system 30 to be transported to the application terminal 60 according to a specified trajectory; the power source system 40 is connected to the superconducting cavity of the acceleration module system 30, and the power source system 40 is configured to provide radio frequency power to the superconducting cavity of the acceleration module system 30 to establish a radio frequency electromagnetic field in the superconducting cavity, so that the charged particle beam is accelerated by the electromagnetic field in the superconducting cavity; the low level and control system 50 is electrically connected to the charged particle injection system 10, the beam transmission system 20, the acceleration module system 30, and the application terminal 60, respectively, and the low level and control system 50 is configured to monitor the operating state of the accelerator by collecting and processing signals of the accelerator, such as temperature, vacuum degree, radio frequency, beam position, beam energy, beam emittance, and the like, and maintain the amplitude and phase stability of the electromagnetic field in the superconducting cavity.

In the above embodiment, preferably, the acceleration module system 30 includes: a superconducting cavity 1 configured to provide energy to a charged particle beam; a low temperature unit 2 configured to provide a required low temperature environment to the superconducting cavity 1; and a vacuum unit 3 connected to the superconducting cavity 1, the vacuum unit 3 being configured to provide a cavity vacuum environment and an interlayer vacuum environment required for operation to the superconducting cavity 1.

In the above embodiment, the power source system 40 mainly includes a power source (not shown in the figure) and a coupler 4, the coupler 4 is connected to the coupling port of the superconducting cavity 1, and the coupler 4 is configured to feed the radio-frequency power output by the power source into the superconducting cavity 1. In this embodiment, the power source is a solid-state power source, the operating frequency is 1.3GHz, and the output power is 10 kW; the operating frequency of the coupler 4 is 1.3GHz and the maximum operating power is 5 kW.

In the above embodiment, the beam delivery system 20 preferably includes a beam conduit, various types of magnet elements, and various types of beam diagnostic elements for charged particle beams. The beam pipeline is processed by 304 stainless steel and is butted with the pipeline of the acceleration module system 30, the joint of the beam pipeline is completely sealed by metal to ensure high vacuum, the beam pipeline is vacuumized by an oil-free dry pump, a molecular pump or an ion pump, and the vacuum degree is lower than 1e-5 Pa; the beam pipeline is provided with beam diagnostic elements for measuring the properties of the charged particle beam such as position, energy, intensity and emittance, and is also provided with a dipolar magnet for charged particle beam deflection, and/or a solenoid and a quadrupole magnet for charged particle beam focusing, and/or a hexapole magnet for de-dispersion, and/or a scanning magnet for irradiation, and other magnet elements required according to application requirements.

In the above embodiment, preferably, the low level and control system50 adopts a digital low-level control system based on FPGA, mainly comprising frequency synthesis, an FPGA digital signal processing platform and upper-layer communication software, wherein the requirement of power stability is less than or equal to 0.3 percent, and the requirement of phase control precision is less than or equal to 0.3 percent in the embodiment⁰。

In the above embodiment, preferably, the charged particles generated by the charged particle injection system 10 are electrons (may be protons or carbon ions), the average current intensity of the charged particle beam is 1 to 5mA, the energy is equal to or greater than 300KeV, the beam charge amount is 1pC to 100pC, the micropulse repetition frequency is 54.17MHz, the micropulse repetition frequency is 1/2/5/10/20Hz, and the micropulse width is 10us to 1 ms.

In the above embodiment, preferably, the low temperature unit 2 includes: the cold screen 2-1 is covered outside the superconducting cavity 1, and the cold screen 2-1 is prepared to reduce the static heat loss of the superconducting cavity 1; a magnetic shield layer (not shown in the figure) arranged in the space between the cold shield 2-1 and the superconducting cavity 1, the magnetic shield layer being configured to shield the earth's ambient magnetic field, reducing the magnetic flux capture of the superconducting cavity 1; the three groups of cold-conducting copper blocks 2-2 are respectively arranged in the equator region of the superconducting cavity 1 and the beam pipeline regions at two sides along the circumferential direction, and the inner surface of the cold-conducting copper block 2-2 is attached to the equator region of the superconducting cavity 1 and the outer surface of the beam pipeline regions; the secondary cold plate 2-3 is arranged above the cold conducting copper blocks 2-2, and one side of the secondary cold plate 2-3 is respectively connected with the three groups of cold conducting copper blocks 2-2 through flexible cold chains 2-4; and at least one refrigerating machine 2-5 is arranged above the secondary cold plate 2-3, and a secondary cold head 2-6 of the refrigerating machine 2-5 is connected with the other side of the secondary cold plate 2-3 through a flexible cold chain 2-4. Therefore, the heat generated by the inner wall of the superconducting cavity 1 is transferred to the secondary cold plate 2-3 through the flexible cold chain 2-4 through the cold conducting copper block 2-2, and is transferred to the secondary cold head 2-6 of the refrigerator 2-5 through the flexible cold chain 2-4, so that the superconducting cavity 1 is maintained in a low-temperature superconducting working state. It should be noted that three groups of cold conducting copper blocks 2-2 are respectively arranged in the equator region of the superconducting cavity 1 and the beam pipeline regions on the two sides along the circumferential direction, only for the case that the superconducting cavity 1 is a single ellipsoidal cavity (i.e. an acceleration unit), but if the superconducting cavity 1 includes a plurality of acceleration units, the number of the cold conducting copper blocks 2-2 required is determined according to the application requirements; and, if the shape of the superconducting cavity 1 is not an ellipsoidal cavity, it is necessary to dispose the cold conducting copper block 2-2 in the heat generating region of the superconducting cavity 1.

In the above embodiment, preferably, the cold conducting copper block 2-2 is in a half-and-half hoop form, and the half-and-half hoops of the cold conducting copper block 2-2 are fastened and connected through screws and nuts; meanwhile, indium sheets (not shown in the figure) are uniformly arranged on the contact interface of the cold conducting copper block 2-2 and the superconducting cavity body 1 and the connection part of the half hoop and the half hoop for enhancing heat conduction; in addition, in order to reduce the residual magnetism of the space where the superconducting cavity 1 is located and effectively fasten, the used screw is a 316L stainless steel screw, the used nut is a silicon bronze nut, and the used gasket is a stainless steel elastic cushion; further, the fastening torque of the screw and the nut is 115N.m, and the thermal resistance of the fastening connection part is ensured to be lower than 1 x 10^-4Km²/W。

In the above embodiment, preferably, temperature sensors (not shown in the figure) are disposed at the outer surface of the equatorial region of the superconducting cavity 1, at the positions of the three sets of cold conducting copper blocks 2-2, the secondary cold plates 2-3, the secondary cold heads 2-6, and the like, for monitoring the temperature change of the superconducting cavity 1; meanwhile, a high-precision heater (not shown in the figure) is arranged on the secondary cold head 2-6 and is used for being matched with a temperature controller and a temperature sensor, so that the conditions that the cooling rate is stable between 30K and 15K and is continuously adjustable between 1min/K and 5min/K are realized, and the temperature gradient of the superconducting cavity 1 in the axial direction is ensured to be less than or equal to 0.025K/cm.

In the above embodiment, it is preferable that fluxgate probes (not shown in the figure) are arranged on the outer surface of the equator region of the superconducting cavity 1 and the outer surfaces of the beam pipe regions on both sides, and the fluxgate probes are required to be capable of accurately measuring the magnetic field strength of less than or equal to 10mGs for residual magnetism measurement and monitoring.

In the above embodiment, preferably, the vacuum unit 3 includes: the vacuum cover 3-1 is covered outside the cold screen 2-1, and the vacuum cover 3-1 is configured to form an interlayer vacuum environment for reducing static heat loss between the vacuum cover 3-1 and the superconducting cavity 1; one end of each of the two groups of vacuum pipelines 3-2 is respectively connected with two flow pipelines of the superconducting cavity 1 through a vacuum angle valve 3-3, and the other end of each of the two groups of vacuum pipelines 3-2 penetrates out of the vacuum cover 3-1 and then is connected with a vacuum pump set (not shown in the figure) so as to form a cavity vacuum environment for accelerating charged particles in a superconducting cavity-pipeline system consisting of the superconducting cavity 1 and the vacuum pipelines 3-2.

In the above embodiment, preferably, the leak rate of the chamber in the vacuum environment is not more than 5e-10mbarL/S at normal temperature, and the vacuum degree of the chamber in the vacuum environment is not more than 5e-5Pa at normal temperature; the vacuum degree of the interlayer vacuum environment is required to be less than or equal to 5e-8mbarL/S at normal temperature, and the vacuum degree of the interlayer vacuum environment is required to be less than or equal to 5e-3Pa at normal temperature.

In the above embodiment, preferably, the vacuum cover 3-1 is made of stainless steel, and the inner and outer surfaces are polished to reduce gas adsorption; the top of the vacuum cover 3-1 is provided with a butt joint port of a refrigerator 2-5, the side is provided with a butt joint port of a vacuum pipeline 3-2, and the bottom is provided with a butt joint port of a coupler 4; a temperature sensor wall penetrating piece 3-4 is reserved on the vacuum cover 3-1 and is used for butt joint of a data line of the temperature sensor; a magnetic probe sensor wall penetrating piece 3-5 is reserved on the vacuum cover 3-1 and is used for butt joint of data lines of the fluxgate probe; the vacuum cover 3-1 is reserved with a backfill port for high-purity nitrogen inflation vacuum recovery and pipeline cleaning, and the cleanliness of the device is guaranteed.

In the above embodiment, preferably, since the cavity wall loss of the superconducting cavity 1 is extremely small, the bandwidth is extremely narrow, and cavity vibration may cause frequency detuning of the superconducting cavity, so as to avoid that vibration of the refrigerator 2-5 is transmitted to the superconducting cavity 1 to affect stable operation thereof, the liquid-helium-free radio frequency superconducting accelerator further comprises a damper 5 arranged at the top of the vacuum hood 3-1, and the refrigerator 2-5 is arranged on the damper 5, so that the vibration amplitude of the secondary cold head 2-6 of the refrigerator 2-5 butted with the superconducting cavity 1 is greatly reduced; meanwhile, the flexible cold chain 2-4 between the secondary cold head 2-6 of the refrigerator 2-5 and the superconducting cavity 1 can effectively prevent the vibration of the refrigerator 2-5 from being transmitted to the superconducting cavity 1.

In the above embodiment, preferably, the superconducting cavity 1 is supported in the vacuum enclosure 3-1 by the supporting structure 6 made of a non-magnetic material, and the fine tuning rod is arranged on the supporting structure 6, so that the position of the superconducting cavity can be fine tuned with high precision, and the requirement for collimation of the superconducting cavity 1 of the accelerator can be met.

In the above embodiment, it is preferable that the inner surface of the superconducting cavity 1 is formed with a thin film of a high temperature superconducting material having a superconducting transition temperature higher than 15K at zero magnetic field and a superheated magnetic field higher than 150mT at 4KMaterials, e.g. Nb₃Sn、MgB₂NbN, iron-based superconducting materials, and the like. The shape and operating frequency of the superconducting cavity 1 are determined by parameters such as the type of charged particles to be accelerated, energy, etc., and may be a transverse magnetic wave (TM) superconducting cavity, a transverse electromagnetic wave (TEM) superconducting cavity, or other superconducting cavity structures.

It should be understood by those skilled in the art that the drawings and the implementation of the present invention are only for convenience of describing the technical solution of the present invention, and the schematic illustration and description are given by taking as an example the liquid helium-free rf superconducting accelerator with a superconducting cavity of one shape and the method for using the same, and do not indicate or imply that the superconducting cavity and the solid conductive cooling structure design in question must have specific shape, size and material limitations, and therefore the scope of protection of the present invention should not be limited thereby. All applications that use a refrigerator-driven cooling method based on solid conduction to accelerate charged particles are within the scope of the present invention.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.