Medium-assisted acceleration structure and method for realizing low loss and high acceleration gradient by using low-temperature environment

Abstract

The invention relates to the technical field of particle accelerators, and provides a medium-assisted acceleration structure and method for realizing low loss and high acceleration gradient by using a low-temperature environment. The structure comprises a medium-assisted acceleration structure body and a low-temperature maintenance and control system, the medium-assisted acceleration structure body comprises a medium layer and a metal cavity to provide electromagnetic field distribution, and the low-temperature maintenance and control system is integrated on the body to maintain the working temperature of the body to be less than or equal to 77K, reduce resistance and dielectric loss and improve a radio frequency breakdown threshold; according to the invention, the radio frequency breakdown threshold is increased at a low temperature, so that the acceleration structure stably operates under higher electric field intensity, and the particle energy gain is increased; the metal resistivity and the dielectric loss are synchronously reduced, the total power loss is reduced, and the energy efficiency is improved; micro-discharge and gas desorption effects are inhibited, the structural stability is improved, and the service life of equipment is prolonged; through low-temperature adaptive design and systematic integration, electromagnetic performance and mechanical reliability are ensured, and the synergistic advantage of low temperature and medium assistance is exerted.

Description

Technical Field

[0001] This invention relates to the field of particle accelerator technology, and more specifically to a medium-assisted acceleration structure and method that utilizes a low-temperature environment to achieve low loss and high acceleration gradient. Background Technology

[0002] As core devices driving basic scientific research and cutting-edge technological development, particle accelerators are constantly driven by the dual demands of high acceleration gradients and low energy loss. However, existing dielectric-assisted accelerator structures face technical bottlenecks at room temperature: on the one hand, the resistive loss of the metal cavity wall and the dielectric loss of the dielectric material constitute the main body of the total power loss, limiting the energy conversion efficiency; on the other hand, the radio frequency breakdown threshold of the metal and dielectric surfaces at room temperature is difficult to overcome, becoming a physical obstacle to improving the acceleration gradient. Although performance can be partially improved by optimizing the dielectric material and cavity design, the intrinsic loss and breakdown threshold of the material at room temperature are close to the physical limit, making it difficult to meet the urgent needs of next-generation high-energy particle accelerators for higher energy, smaller size, and better economy.

[0003] To address the aforementioned issues, this invention proposes an innovative approach that deeply integrates low-temperature environment with medium-assisted acceleration structure. Through the synergistic effect of low-temperature physical effects and medium electromagnetic optimization, it breaks through the bottleneck of room-temperature technology and opens up a new development path for particle acceleration technology. Summary of the Invention

[0004] To address the aforementioned problems, this invention aims to provide a dielectric-assisted acceleration structure and method that utilizes a cryogenic environment to achieve low loss and high acceleration gradient. This technology is applicable to particle accelerators in basic scientific research and cutting-edge technology applications. It aims to improve the acceleration gradient, energy efficiency, operational stability, and reliability of accelerators through the synergistic effect of the cryogenic environment and the dielectric-assisted acceleration structure. By operating the dielectric-assisted acceleration structure in a cryogenic environment (especially 77K and below), the resistive loss of the metal cavity and the dielectric loss of the dielectric layer can be significantly reduced, while simultaneously increasing the radio frequency breakdown threshold. This overcomes the performance bottleneck of acceleration structures at room temperature and provides key technological support for next-generation high-performance particle accelerators.

[0005] The technical solution adopted in this invention is: a dielectric-assisted acceleration structure that utilizes a low-temperature environment to achieve low loss and high acceleration gradient. The structure includes: a dielectric-assisted acceleration structure body, comprising a dielectric layer and a metal cavity, wherein the dielectric layer and the metal cavity work together to provide an electromagnetic field distribution for particle acceleration; and a low-temperature maintenance and control system, integrated with the dielectric-assisted acceleration structure body, for maintaining the body in a low-temperature environment with an operating temperature ≤77K, thereby reducing the resistive loss of the metal cavity and the dielectric loss of the dielectric layer, and improving the radio frequency breakdown threshold.

[0006] The dielectric layer is made of a material whose dielectric loss is significantly reduced at low temperatures, including microwave dielectric ceramics of high-purity alumina and magnesium oxide ceramics; the dielectric loss tangent (tanδ) of the material at 77K is much lower than its value at 300K; the coefficient of thermal expansion of the dielectric layer material is matched with that of the metal cavity material in the temperature range of 300K to 77K to prevent failure caused by thermal stress.

[0007] The metal cavity is made of oxygen-free copper or copper alloy, whose resistivity drops sharply at low temperatures. The dielectric layer and the metal cavity are connected by a reliable connection process that adapts to large temperature differences, including active metal brazing and flexible transition layer design, to ensure a strong interface bond, reliable vacuum sealing, and no additional microwave loss at low temperatures.

[0008] The cryogenic maintenance and control system includes: a cryogenic thermostat for providing an adiabatic environment to reduce radiative heat transfer and residual gas convective heat transfer; a cold source, using liquid nitrogen, liquid neon, liquid hydrogen, or liquid helium as the primary cold source; a cold transfer component for efficiently and uniformly transferring cold energy to the medium-assisted acceleration structure body; a temperature sensor located at a key position on the body for monitoring temperature; and a control unit for adjusting the power of the cold source or heater based on feedback from the temperature sensor to achieve precise and stable control of the operating temperature, with temperature fluctuations controlled within ±0.5K.

[0009] The cryogenic maintenance and control system also includes a vacuum maintenance device for maintaining a high vacuum environment with a vacuum level ≤10. -5 Pa, to eliminate gas conduction and prevent gas condensation at low temperatures; the high-voltage section of the acceleration structure is designed for electrical insulation at low temperatures.

[0010] The dielectric-assisted acceleration structure operates in TM020-π mode; the dielectric layer is either an integral bushing or multiple discretely arranged dielectric blocks to optimize the electromagnetic field distribution and reduce the loss of the cavity metal wall.

[0011] The operating temperature of the cryogenic maintenance and control system can be further selected as liquid nitrogen temperature range (77K), liquid neon or liquid hydrogen temperature range (20K-30K), or liquid helium temperature range (≤4.2K) to adjust the cryogenic environment according to material properties and system requirements.

[0012] A method for achieving low loss and high acceleration gradient in a dielectric-assisted acceleration structure using a cryogenic environment, the method comprising the following steps: The dielectric-assisted acceleration structure, which includes a dielectric layer and a metal cavity, is placed in a low-temperature environment of ≤77K; The low-temperature environment significantly reduces the resistive loss of the metal cavity and the dielectric loss of the dielectric layer. Increasing the RF breakdown threshold of the metal and dielectric surfaces can achieve higher acceleration gradients, lower power losses, and stronger operational stability and reliability.

[0013] The low-temperature environment is achieved through direct immersion, conductive cooling, or a hybrid cooling method. In direct immersion, the acceleration structure is directly immersed in liquid nitrogen or a lower-temperature liquid. In conductive cooling, the cooling capacity of the mechanical refrigeration unit is transferred to the acceleration structure through a solid cold conduction link. In hybrid cooling, the advantages of direct immersion and conductive cooling are combined to balance cooling capacity and system complexity.

[0014] The dielectric-assisted acceleration structure selects different cavity shapes, electromagnetic modes, and dielectric loading methods according to different application requirements. The dielectric loading methods include integral dielectric ring / shroud type, discrete dielectric block / plate type, or gradient / composite dielectric type, so as to achieve optimal electromagnetic field distribution and thermal stress management at low temperatures. The method can also be combined with other advanced technologies to further improve the performance limit of the acceleration structure.

[0015] The implementation of this invention will bring about the following significant beneficial effects: This invention significantly improves the radio frequency breakdown threshold of metal and dielectric surfaces by using a low-temperature environment, enabling the acceleration structure to operate stably under electric field strengths far exceeding the room temperature limit. This greatly increases the energy gain per unit length of particles, providing technical support for reducing accelerator size and construction costs.

[0016] This invention achieves a simultaneous reduction in metal resistivity and dielectric loss at low temperatures, resulting in a significant decrease in the total power loss of the acceleration structure. This allows for a higher acceleration gradient at the same input power, or a significant reduction in energy consumption at the same acceleration gradient, thereby improving the overall energy efficiency of the accelerator.

[0017] The low-temperature suppression of micro-discharge and gas desorption effects in this invention reduces the causes of radio frequency breakdown; at the same time, the thermal expansion coefficient of the material decreases at low temperatures, improving the structural dimensional stability, thereby extending the equipment life and ensuring long-term operational reliability.

[0018] This invention ensures the electromagnetic performance and mechanical reliability of the structure in low-temperature environments by selecting low-temperature compatible medium materials, using low-temperature reliable connection processes, and designing a precision temperature control system. Through systematic integrated design, it achieves coordinated operation between the low-temperature maintenance and control system and the accelerated structure, giving full play to the synergistic advantages of low temperature and medium assistance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Figure labeling: 1-Medium-assisted acceleration structure body, 11-Medium layer, 12-Metal cavity, 2-Cryogenic maintenance and control system. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and embodiments: Example 1: Integral Dielectric Bushing Acceleration Structure Based on Liquid Nitrogen Cooling like Figure 1 As shown, this embodiment provides a medium-assisted acceleration structure that utilizes a low-temperature environment to achieve low loss and high acceleration gradient, which includes a low-temperature medium-assisted acceleration structure body 1 and a low-temperature maintenance and control system 2.

[0022] The cryogenic medium-assisted acceleration structure body 1 includes the following: Dielectric layer 11: High-purity alumina ceramic is selected as the material for dielectric layer 11. The dielectric loss tangent (tanδ) of this material at 77K is significantly lower than that at 300K, and its coefficient of thermal expansion matches that of the oxygen-free copper metal cavity 12 in the temperature range of 300K to 77K. This effectively prevents problems such as dielectric cracking, delamination, or metal-dielectric interface failure caused by thermal stress. Dielectric layer 11 is designed as an integral bushing structure and is connected to the metal cavity 12 through a flexible transition layer design and active metal brazing process, ensuring a strong interface bond and reliable vacuum sealing at low temperatures without introducing additional microwave loss.

[0023] Metal cavity 12: Made of high-purity oxygen-free copper, which exhibits a sharp decrease in resistivity at low temperatures. The structural design of metal cavity 12 takes into account the uniformity of low-temperature shrinkage to avoid stress concentration and ensure structural stability in low-temperature environments.

[0024] Electromagnetic mode: The acceleration structure body 1 operates in TM020-π mode, utilizing the electromagnetic field boundary conditions of the medium-vacuum interface to optimize the electric field distribution within the cavity, thereby confining electromagnetic energy more concentrated in the acceleration region.

[0025] Regarding cryogenic maintenance and control systems 2 Low-temperature thermostat: Employs a high-vacuum multi-layered insulating Dewar to provide an insulating environment for the acceleration structure, greatly reducing radiative heat transfer and residual gas convective heat transfer.

[0026] Cold source and cooling path: Liquid nitrogen is selected as the primary cold source, and high-conductivity oxygen-free copper strip is used as the cooling component to efficiently and uniformly conduct the cold energy to the acceleration structure body 1, especially the metal cavity 12 and the dielectric layer 11.

[0027] Temperature monitoring and active temperature control: Platinum resistance temperature sensors are placed at key locations such as the center of the dielectric block, the metal cavity wall, and near the coupler in the acceleration structure. The power of the cold source or heater is adjusted through a feedback control system to achieve precise and stable operation at 77K, with temperature fluctuations controlled within ±0.5K, thus ensuring high stability of the acceleration field.

[0028] Vacuum and Insulation System: Maintains a high vacuum environment inside the Dewar, with a vacuum level ≤10. -5 Pa is used to eliminate gas conduction and prevent gas condensation at low temperatures. Simultaneously, the high-voltage section of the acceleration structure is designed for low-temperature electrical insulation.

[0029] In this embodiment, the dielectric-assisted acceleration structure, comprising a dielectric layer 11 and a metal cavity 12, is placed in a cryogenic environment cooled by liquid nitrogen. Under cryogenic conditions, the resistive loss of the metal cavity 12 and the dielectric loss of the dielectric layer 11 are significantly suppressed, while the radio frequency breakdown threshold of the metal and dielectric surfaces is greatly improved. Within the acceleration structure, particles are accelerated in TM020-π mode using an optimized electric field distribution, achieving a higher acceleration gradient, lower power loss, and stronger operational stability and reliability.

[0030] The specific steps for constructing the structure in this embodiment are as follows: S1, Preparation and Installation of Dielectric Layer 11 High-purity alumina ceramic was selected as the material for the dielectric layer 11, and it was manufactured into an integral bushing structure through precision machining. During the machining process, dimensional accuracy and surface quality were strictly controlled to ensure the precision of its fit with the metal cavity 12.

[0031] The dielectric bushing is connected to the oxygen-free copper metal cavity 12 using an active metal brazing process. Before brazing, the connection surfaces of the dielectric bushing and the metal cavity 12 are rigorously cleaned and pretreated to remove impurities such as oil and oxides to ensure brazing quality. During the brazing process, parameters such as temperature, time, and atmosphere are precisely controlled to ensure a strong interface bond, reliable vacuum sealing, and no additional microwave loss.

[0032] S2, Metal cavity 12 machining The metal cavity 12 is made of high-purity oxygen-free copper. CNC machining equipment was used to process the shape and dimensions of the cavity according to the design requirements, paying particular attention to ensuring the geometric accuracy of the cavity, such as cylindricity and coaxiality. The cavity structure design fully considers the uniformity of low-temperature shrinkage to avoid stress concentration areas. Rounded corners are used at the connection points of the cavity to reduce stress concentration.

[0033] S3, Low-Temperature Thermostat and Cold Source Setup A high-vacuum, multi-layered insulated Dewar is assembled as a cryogenic thermostat. Multiple layers of insulation material, such as aluminum foil and spacers, are laid between the inner and outer walls of the Dewar to reduce radiative heat transfer. Simultaneously, the Dewar undergoes rigorous leak testing to ensure its vacuum level meets requirements.

[0034] Liquid nitrogen is used as the primary cold source, and a liquid nitrogen storage and transportation device is prepared. A high-conductivity oxygen-free copper strip is used as a heat transfer component to conduct the cooling capacity of the liquid nitrogen to the acceleration structure body 1. When installing the heat transfer copper strip, ensure good contact between it and the acceleration structure body 1 and the cold source; this can be achieved through bolting or welding to reduce contact thermal resistance.

[0035] S4. Installation of temperature monitoring and control system Platinum resistance temperature sensors are installed at key locations such as the center of the dielectric block in the acceleration structure, the metal cavity wall, and near the coupler. The sensors must be securely installed and have good thermal contact with the part being measured to ensure accurate temperature measurements.

[0036] Connect the temperature sensor to the control unit, which uses a programmable logic controller (PLC) or a dedicated temperature control instrument. Set the target temperature to 77K in the control unit, with a temperature fluctuation control range of ±0.5K. Precise and stable control of the operating temperature is achieved by adjusting the liquid nitrogen supply or the heater power (the heater can be installed in an appropriate location as needed).

[0037] S5, Vacuum and Insulation System Setup Connect a vacuum pump unit to the Dewar flask and evacuate the Dewar flask to a vacuum level of ≤10. -5 Pa. During the vacuuming process, the vacuum level must be strictly monitored to ensure that the requirements are met.

[0038] For the high-voltage part of the acceleration structure, low-temperature electrical insulation design should be carried out, such as wrapping the high-voltage components with insulation materials with good low-temperature performance, or setting a reasonable insulation spacing.

[0039] The debugging and running of this embodiment includes the following steps: First, after the structural construction is completed, the entire system should be checked for airtightness to ensure there are no issues with liquid nitrogen or vacuum leaks. A helium mass spectrometer leak detector can be used for comprehensive testing of the system.

[0040] Then, the liquid nitrogen supply system is activated, injecting liquid nitrogen into the cryostat to begin cooling the accelerated structure. During the cooling process, the temperature sensor readings are closely monitored to observe the temperature drop. When the temperature approaches 77K, the control unit begins to adjust the liquid nitrogen supply or heater power to stabilize the temperature within the set range.

[0041] Finally, once the temperature stabilizes, the microwave source and other equipment related to particle acceleration are activated, initiating the acceleration structure's operation. Specialized monitoring equipment, such as acceleration field monitors and power meters, is used to monitor the acceleration structure's performance parameters in real time, including acceleration gradient, power loss, and radio frequency breakdown. Relevant data is recorded to assess whether the acceleration structure's performance meets the expected targets.

[0042] This embodiment requires regular system maintenance, including checking the operation of the liquid nitrogen supply system to ensure an adequate supply of liquid nitrogen. Simultaneously, the vacuum level of the cryostat should be checked, and if necessary, a vacuum replenishment operation should be performed. The performance of the acceleration structure should be analyzed based on actual operating data. If indicators such as acceleration gradient or stability are found to be suboptimal, optimizations can be made to the electromagnetic mode, the connection between the dielectric layer 11 and the metal cavity 12, etc. For example, the acceleration field distribution can be optimized by adjusting the frequency and power of the microwave source; or the connection between the dielectric layer 11 and the metal cavity 12 can be inspected and repaired to ensure the reliability of the connection.

[0043] Example 2: Discrete Medium Block Acceleration Structure Based on Mechanical Refrigeration Machine Conductive Cooling In this embodiment, the cryogenic medium-assisted acceleration structure body 1 includes the following: Dielectric layer 11: Employs a microwave dielectric ceramic with a specific formulation to meet the requirement of significantly reduced dielectric loss at low temperatures, and its coefficient of thermal expansion matches that of the copper alloy metal cavity 12 within the target temperature range. The dielectric layer 11 is designed as multiple discretely arranged dielectric blocks, applied at specific locations of the peak electric field within the cavity, facilitating optimized field distribution and localized cooling. The dielectric blocks are connected to the metal cavity 12 via a flexible transition layer and an active metal brazing process, ensuring a reliable connection at low temperatures.

[0044] Metal cavity 12: Made of copper alloy, its resistivity decreases significantly at low temperatures. The cavity structure is optimized based on the arrangement of discrete dielectric blocks to ensure overall electromagnetic performance.

[0045] Electromagnetic mode: Select the appropriate electromagnetic mode based on the layout of the discrete dielectric block and the cavity structure to achieve efficient particle acceleration.

[0046] In this embodiment, the low-temperature maintenance and control system 2 includes the following: Low-temperature thermostat: It also uses a high-vacuum multi-layer thermal insulation Dewar to provide a good thermal insulation environment.

[0047] Cold source and cooling path: A mechanical refrigeration unit (such as a G-M refrigeration unit) is used as the primary cold source, and the cold energy is transferred to the acceleration structure through a solid cold conduction link (high conductivity copper rod). This conductive cooling solution does not require cryogenic liquids, is easy to operate, and is suitable for space-constrained scenarios.

[0048] Temperature monitoring and active temperature control: Temperature sensors are placed at key locations in the acceleration structure. The control unit adjusts the power of the refrigerator or heater based on sensor feedback to achieve precise and stable control of the operating temperature, with temperature fluctuations controlled within ±0.5K.

[0049] Vacuum and Insulation System: Maintain a high vacuum environment, perform electrical insulation design at low temperatures, and ensure stable operation of the system.

[0050] In this embodiment, the cooling energy generated by the mechanical refrigeration unit is transferred to the acceleration structure via a conduction link, maintaining it in a low-temperature environment (e.g., 77K). Under this low-temperature environment, the performance of the acceleration structure is improved, and particles are accelerated under the optimized electric field distribution of the discrete dielectric block, achieving a highly efficient and stable acceleration effect.

[0051] The specific steps for constructing the structure in this embodiment are as follows: S1. Preparation and Installation of Media Blocks Discrete dielectric blocks are fabricated using microwave dielectric ceramics with a specific formulation. The dimensional accuracy and performance stability of the dielectric blocks are ensured through molding and sintering processes. During sintering, the temperature profile and atmospheric conditions are strictly controlled to ensure the dielectric blocks exhibit low dielectric loss characteristics at low temperatures.

[0052] A discrete dielectric block is loaded at a specific location where the electric field peaks within the cavity. During installation, specialized positioning fixtures are used to ensure the positioning accuracy of the dielectric block. The dielectric block is connected to the copper alloy metal cavity 12 via a flexible transition layer design and an active metal brazing process. Before sintering, the connecting surfaces of the dielectric block and the metal cavity 12 are treated to improve the connection strength. During the welding process, temperature and time are precisely controlled to ensure a strong bond between the dielectric block and the metal cavity 12.

[0053] S2, Metal cavity 12 machining A copper alloy was selected to fabricate the metal cavity 12. The shape and structure of the cavity were designed based on the layout of the discrete dielectric block and the electromagnetic mode requirements. Machining methods, such as milling and drilling, were used to process each part of the cavity. During machining, care was taken to ensure the surface roughness and dimensional accuracy of the cavity to minimize its impact on the electromagnetic field distribution.

[0054] S3, Low-Temperature Thermostat and Cold Source Setup Assemble a high-vacuum multilayer thermally insulating Dewar as a cryogenic thermostat, using the same method as in Example 1.

[0055] Install a mechanical refrigeration unit (such as a G-M refrigeration unit) as the primary cold source. Connect the cold head of the refrigeration unit to a solid-state cold conduction link (high-conductivity copper rod) to ensure efficient transfer of cold energy. During installation, ensure good contact between the cold head and the copper rod. Special connection methods, such as bolt tightening and applying thermal grease, can be used to reduce contact thermal resistance.

[0056] S4. Installation of temperature monitoring and control system Temperature sensors are installed at key locations in the acceleration structure, using the same method as in Example 1.

[0057] Connect the temperature sensor to the control unit, set the target temperature to 77K, and the temperature fluctuation control range to ±0.5K. Based on the signal feedback from the sensor, the control unit adjusts the operating power of the refrigerator or the heater power to achieve precise and stable temperature control.

[0058] S5, Vacuum and Insulation System Setup The Dewar was evacuated to achieve the required vacuum level, and electrical insulation design at low temperature was performed, using the same method as in Example 1.

[0059] The debugging and operation of this embodiment includes the following steps: First, a comprehensive inspection and debugging of the entire system is conducted, including operational testing of the chiller and functional verification of the temperature control system. This ensures that the chiller can start and operate normally, and that the temperature control system can accurately regulate the temperature.

[0060] Then, the mechanical refrigeration unit is started to begin cooling the accelerated structure. Temperature changes are monitored, and when the temperature approaches the target value, the control unit starts working to stabilize the temperature within the set range.

[0061] Finally, once the temperature stabilizes, the particle acceleration equipment is activated to test the performance of the acceleration structure. Using relevant monitoring instruments, parameters such as acceleration gradient and power loss are measured to evaluate the performance of the acceleration structure under conductive cooling and discrete dielectric block design.

[0062] This implementation requires regular maintenance of the mechanical refrigeration unit, including checking all components such as the compressor, condenser, and evaporator to ensure their normal operation. The heat dissipation components should be cleaned to ensure good heat dissipation. The electromagnetic performance of the acceleration structure should be analyzed based on operational data. If the electric field distribution is found to be unsatisfactory, the position of the discrete dielectric blocks can be adjusted or dielectric blocks with different properties can be replaced to optimize the acceleration field distribution. Simultaneously, the temperature control system should be calibrated regularly to ensure the accuracy of temperature control.

[0063] Example 3: Hybrid Cooling Gradient / Composite Medium Acceleration Structure The cryogenic medium-assisted acceleration structure body 1 in this embodiment includes the following: Dielectric layer 11: Employs a gradient / composite dielectric design, composed of materials with different dielectric constants or loss characteristics, exhibiting a radial gradient. The selected material possesses low dielectric loss characteristics at low temperatures and matches the thermal expansion coefficient of the metal cavity 12 material. Dielectric layer 11 and metal cavity 12 are connected via a flexible transition layer design, adapting to large temperature variations and ensuring reliable connection at low temperatures.

[0064] Metal cavity 12: Made of oxygen-free copper, which reduces resistivity at low temperatures. The cavity structure is optimized according to the gradient / composite dielectric design.

[0065] Electromagnetic mode: Select an electromagnetic mode suitable for gradient / composite medium distribution to achieve optimal electromagnetic field distribution and thermal stress management at low temperatures.

[0066] The low-temperature maintenance and control system 2 in this embodiment includes the following: Low-temperature thermostat: high-vacuum multi-layer thermally insulated Dewar.

[0067] Cold source and cooling path: A hybrid cooling system is adopted, using liquid nitrogen to cool the radiation screen and then using a mechanical refrigerator (such as a pulse tube refrigerator) to cool the core acceleration structure, balancing cooling capacity and system complexity.

[0068] Temperature monitoring and active temperature control: Through temperature sensors and feedback control systems placed in key locations, precise and stable control of the operating temperature is achieved.

[0069] Vacuum and Insulation Systems: Maintaining a high vacuum environment and designing electrical insulation at low temperatures.

[0070] This embodiment utilizes a hybrid cooling method to maintain the acceleration structure at a suitable low-temperature environment (e.g., 20K-30K). At low temperatures, the gradient / composite medium structure demonstrates its advantages, and combined with the improved material properties brought about by the low temperature, the acceleration structure achieves higher performance, allowing particles to be accelerated in an optimized electromagnetic field.

[0071] The structural construction in this embodiment includes the following steps: S1, Gradient / Composite Dielectric Layer 11 Preparation and Installation According to design requirements, materials with different dielectric constants or loss characteristics are selected and composite layers 11 are fabricated through a composite process. For example, a multilayer composite method can be used to make the dielectric constant of the dielectric layer 11 gradually change radially. During the fabrication process, the thickness and performance parameters of each layer are strictly controlled.

[0072] The gradient / composite dielectric layer 11 is connected to the oxygen-free copper metal cavity 12 via a flexible transition layer design. The flexible transition layer can be made of materials with good flexibility and low-temperature performance, such as special rubber or elastic metal materials. During installation, ensure good adhesion and sealing between the flexible transition layer and the dielectric layer 11 and the metal cavity 12 to adapt to large temperature differences and guarantee a reliable connection at low temperatures.

[0073] S2, Metal cavity 12 machining The metal cavity 12 is made of oxygen-free copper material, and its shape and structure are optimized according to the design of the gradient / composite dielectric layer 11. Advanced processing techniques, such as CNC machining and EDM, are used to ensure the machining accuracy of the cavity. Necessary interfaces are provided on the cavity for connection with components such as cold source conduction links and temperature sensors.

[0074] S3, Low-Temperature Thermostat and Cold Source Setup Assemble a high-vacuum multilayer thermally insulated Dewar as a cryogenic thermostat.

[0075] A hybrid cooling method is employed, involving the installation of a liquid nitrogen-cooled radiation screen and a mechanical chiller (such as a pulse tube chiller). A liquid nitrogen storage device is connected to the radiation screen, and liquid nitrogen is supplied via pipelines to cool the screen. Simultaneously, the cold head of the mechanical chiller is connected to the core acceleration structure via a solid-state cold conduction link, ensuring effective transfer of cooling energy to the acceleration structure.

[0076] S4. Installation of temperature monitoring and control system Temperature sensors are installed at key locations in the acceleration structure to monitor temperature changes in real time.

[0077] Connect the temperature sensor to the control unit, set a suitable operating temperature range (e.g., 20K - 30K), and ensure temperature fluctuation control is ±0.5K. Based on sensor feedback, the control unit adjusts the liquid nitrogen supply and the mechanical chiller's operating power to achieve precise and stable temperature control.

[0078] S5, Vacuum and Insulation System Setup The Dewar is evacuated to the specified vacuum level, and low-temperature electrical insulation is designed to ensure the safe operation of the system.

[0079] The debugging and operation in this embodiment includes the following steps: First, the hybrid cooling system was tested. The liquid nitrogen cooling system was started first to cool the radiation screen, and the temperature drop of the radiation screen was observed. Then, the mechanical chiller was started to cool the core acceleration structure, and the temperature change of the acceleration structure was monitored.

[0080] Then, when the temperature approaches the target range, the control unit starts working, precisely adjusting the output of the cold source to stabilize the temperature within the set range.

[0081] Finally, once the temperature stabilized, the particle acceleration system was activated to conduct comprehensive testing of the acceleration structure's performance. Various monitoring methods were used to evaluate whether indicators such as acceleration gradient, power loss, and thermal stress met the design requirements.

[0082] In this embodiment, the operating status of the liquid nitrogen cooling system and mechanical refrigeration unit needs to be checked regularly to ensure the supply of liquid nitrogen and the cooling effect of the refrigeration unit. The cold source conduction links should be checked for looseness or damage, and repaired or replaced promptly.

[0083] Based on operational data and performance test results, the design and installation of the gradient / composite dielectric layer 11 are optimized. For example, the gradient distribution of the dielectric layer 11 is adjusted or some materials are replaced to further improve the performance of the acceleration structure. Simultaneously, the temperature control system is continuously optimized to improve the accuracy and stability of temperature control.

[0084] The above embodiments are merely specific examples of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art, within the scope of the present invention's concept, can make various changes, modifications, substitutions, and variations to the above embodiments, all of which should fall within the scope of protection of the present invention.

Claims

1. A dielectric-assisted acceleration structure that utilizes a low-temperature environment to achieve low loss and high acceleration gradient, characterized in that, The structure includes: The dielectric-assisted acceleration structure body includes a dielectric layer and a metal cavity, which work together to provide an electromagnetic field distribution for particle acceleration; The cryogenic maintenance and control system, integrated with the dielectric-assisted acceleration structure body, is used to maintain the body in a cryogenic environment with an operating temperature ≤77K, so as to reduce the resistive loss of the metal cavity and the dielectric loss of the dielectric layer, and improve the radio frequency breakdown threshold.

2. The dielectric-assisted acceleration structure for achieving low loss and high acceleration gradient using a low-temperature environment according to claim 1, characterized in that, The dielectric layer is made of a material whose dielectric loss is significantly reduced at low temperatures, including microwave dielectric ceramics of high purity alumina ceramics and magnesium oxide ceramics. The dielectric loss tangent (tanδ) of the material at 77K is much lower than that at 300K; the coefficient of thermal expansion of the dielectric layer material is matched with that of the metal cavity material in the temperature range of 300K to 77K to prevent failure caused by thermal stress.

3. The dielectric-assisted acceleration structure for achieving low loss and high acceleration gradient using a low-temperature environment according to claim 1, characterized in that, The metal cavity is made of oxygen-free copper or copper alloy, whose resistivity decreases sharply at low temperatures. The dielectric layer and the metal cavity are connected by a reliable connection process that adapts to large temperature differences, including active metal brazing and flexible transition layer design, to ensure a strong interface bond at low temperatures, reliable vacuum sealing, and no introduction of additional microwave loss.

4. The dielectric-assisted acceleration structure for achieving low loss and high acceleration gradient using a low-temperature environment as described in claim 1, characterized in that, The cryogenic maintenance and control system includes: Low-temperature thermostats are used to provide an insulating environment and reduce radiative heat transfer and residual gas convective heat transfer. For the cold source, liquid nitrogen, liquid neon, liquid hydrogen, or liquid helium are selected as the primary cold source. The cooling component efficiently and uniformly transfers the cooling energy to the medium-assisted acceleration structure body; Temperature sensors are arranged at key locations on the body to monitor temperature; The control unit adjusts the power of the cold source or the heater based on feedback from the temperature sensor to achieve precise and stable control of the operating temperature, with temperature fluctuations controlled within ±0.5K.

5. A dielectric-assisted acceleration structure for achieving low loss and high acceleration gradient using a low-temperature environment, as described in claim 4, is characterized in that... The cryogenic maintenance and control system also includes a vacuum maintenance device for maintaining a high vacuum environment with a vacuum level ≤10. -5 Pa, to eliminate gas conduction and prevent gas condensation at low temperatures; the high-voltage section of the acceleration structure is designed for electrical insulation at low temperatures.

6. A dielectric-assisted acceleration structure for achieving low loss and high acceleration gradient using a low-temperature environment according to any one of claims 1-5, characterized in that, The dielectric-assisted acceleration structure operates in TM020-π mode; the dielectric layer is either an integral bushing or multiple discretely arranged dielectric blocks to optimize the electromagnetic field distribution and reduce the loss of the cavity metal wall.

7. The medium-assisted acceleration structure according to any one of claims 1-5, characterized in that, The operating temperature of the cryogenic maintenance and control system can be further selected as liquid nitrogen temperature range (77K), liquid neon or liquid hydrogen temperature range (20K-30K), or liquid helium temperature range (≤4.2K) to adjust the cryogenic environment according to material properties and system requirements.

8. A method for achieving low loss and high acceleration gradient in a dielectric-assisted acceleration structure using a low-temperature environment, characterized in that, The method includes the following steps: The dielectric-assisted acceleration structure, which includes a dielectric layer and a metal cavity, is placed in a low-temperature environment of ≤77K; The low-temperature environment significantly reduces the resistive loss of the metal cavity and the dielectric loss of the dielectric layer. Increasing the RF breakdown threshold of the metal and dielectric surfaces can achieve higher acceleration gradients, lower power losses, and stronger operational stability and reliability.

9. The method for achieving low loss and high acceleration gradient of a dielectric-assisted acceleration structure using a low-temperature environment according to claim 8, characterized in that, The low-temperature environment is achieved through direct immersion, conductive cooling, or a hybrid cooling method. In the direct immersion method, the acceleration structure is directly immersed in liquid nitrogen or a lower cryogenic liquid; In conduction cooling, the cooling capacity of the mechanical refrigerator is transferred to the acceleration structure through a solid cold conduction link; Hybrid cooling combines the advantages of direct immersion cooling and conduction cooling to balance cooling capacity and system complexity.

10. A method for achieving low loss and high acceleration gradient of a dielectric-assisted acceleration structure using a low-temperature environment, as described in claim 8 or 9, characterized in that... The dielectric-assisted acceleration structure selects different cavity shapes, electromagnetic modes, and dielectric loading methods according to different application requirements. The dielectric loading methods include integral dielectric ring / shroud type, discrete dielectric block / plate type, or gradient / composite dielectric type, so as to achieve optimal electromagnetic field distribution and thermal stress management at low temperatures. The method can also be combined with other advanced technologies to further improve the performance limit of the acceleration structure.

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