Conduction-Cooled SRF Cryomodule for High-Current Accelerators
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Solution Overview
Problem
Conventional superconducting radio-frequency (SRF) cryomodules for particle accelerators are costly and complex, limiting their widespread use due to the need for large cryogenic plants and liquid helium, which increases capital and operating costs and poses safety hazards.
Innovation Solution
A compact, conduction-cooled SRF cryomodule using commercial Gifford-McMahon closed-cycle refrigerators replaces the conventional cryogenic plant, featuring a multi-layer SRF cavity, dual coaxial input couplers, high-order modes dampers, thermal and magnetic shields, and multiple cryocoolers, eliminating the need for a helium liquefier and pressure vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional liquid helium cryogenic plants are used to cool SRF cavities, then the superconducting state is achieved and RF losses are minimized, but the capital cost, operating cost, and system complexity increase substantially
Solution Approach 1:
The patent extracts and eliminates the complex liquid helium cryogenic plant from the system by adopting conduction cooling with closed-cycle refrigerators. This removes the need for helium storage, pumping, and distribution infrastructure while maintaining the necessary cooling function for superconducting operation.
Solution Approach 2:
The patent replaces the mechanical liquid helium circulation system with a conduction-based cooling system using solid thermal pathways. Heat is conducted directly from the SRF cavity through thermal straps and mounting structures to the cold heads of closed-cycle refrigerators, eliminating the need for fluid circulation mechanics.
2Temperature
If liquid helium is used for cooling, then effective cooling is achieved, but safety hazards and operational complexity increase
Solution Approach 1:
The patent employs air or nitrogen as the working fluid in closed-cycle refrigerators instead of liquid helium. These gases are abundant, non-hazardous, and can be easily contained in closed cycles, eliminating the safety hazards associated with liquid helium while providing effective cooling through the conduction pathway.
3Reliability
If conventional cryogenic systems are used, then reliable cooling is achieved, but capital and operating costs increase
Solution Approach 1:
The patent employs commercial off-the-shelf closed-cycle refrigerator units that can be purchased from multiple vendors, providing universal, standardized cooling solutions. These units integrate compression, condensation, expansion, and evaporation functions in single packages, reducing overall system cost while maintaining reliable cooling performance for SRF applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly reduces capital and operating costs, simplifies operations, and eliminates liquid cryogen hazards, enabling low-cost, high-current SRF accelerators suitable for industrial applications like environmental remediation, such as treating wastewater and flue gases, while maintaining high performance.
Implementation Method 1
conduction-cooled SRF cryomodule
Implementation Method 2
cooling the superconducting state is achieved by cooling niobium SRF cavities to below the transition temperature of 9.2K
Implementation Method 3
thermal shield
Implementation Method 4
magnetic shields
Data Source
AI summary
A high-current, compact, conduction cooled superconducting radio-frequency cryomodule for particle accelerators. The cryomodule will accelerate an electron beam of average current up to 1 ampere in continuous wave (CW) mode or at high duty factor. The cryomodule consists of a single-cell superconducting radio-frequency cavity made of high-purity niobium, with an inner coating of Nb3Sn and an outer coating of pure copper. Conduction cooling is achieved by using multiple closed-cycle refrigerators. Power is fed into the cavity by two coaxial couplers. Damping of the high-order modes is achieved by a warm beam-pipe ferrite damper.