基于液氮冷源超导磁体氦气循环预冷系统设计

Design of helium gas cycle pre-cooling system for superconducting magnet based on liquid nitrogen cooling source

为了提高超导磁体300—80 K预冷过程中的降温效率和安全性,开发了一种新的预冷方法。设计了一台以液氮为冷源、氦气为循环介质的可控温预冷装置,对其内部结构进行了优化设计,包括低温风机、板式换热器、气动调节阀、翅片换热器等主要组成部分,整个装置与磁体构成一个闭合循环系统。在预冷装置的作用下,该超导磁体从300 K到80 K的预冷时间约为46 h,并保证内部最大温差小于30 K,降温时间较之前间接预冷方法缩短60%,为磁体冷试验初期制定合适的预冷方案提供了参考。

In order to improve the cooling efficiency and safety of superconducting magnets during 300-80 K pre-cooling,a new pre-cooling method was developed.In this paper,a controllable temperature pre-cooler with liquid nitrogen as cooling source and helium gas as circulating medium was designed.Its internal structure was optimized,including cryo-fan,plate heat exchanger,pneumatic control valve,fin heat exchanger and other main components.The whole device and magnet form a closed cycle system.Under the action of the pre-cooler,the pre-cooling time of the superconducting magnet from 300 K to 80 K is about 46 h,and the maximum temperature difference within the superconducting magnet is less than 30 K.The cooling time is reduced by 60%compared with the previous indirect pre-cooling method,which provides a reference for the development of an appropriate pre-cooling scheme in the initial stage of the magnet cold test.