磁场对传导冷却超导磁体系统制冷机的影响  

EFFECT OF MAGNETIC FIELD ON THE CRYOCOOLERS FOR CONDUCTION-COOLD SUPERCONDUCTING MAGNET

作　　者：李兰凯[1,2] 赵保志[1] 戴银明[1] 倪志鹏[1,2] 王秋良[1] 

机构地区：[1]中国科学院电工研究所,北京100190 [2]中国科学院研究生院,北京100190

出　　处：《低温物理学报》2012年第3期194-199,共6页Low Temperature Physical Letters

摘　　要：用于传导冷却超导磁体系统的GM制冷机处于强磁场环境中,由于二级蓄冷器的填充材料其性能随外部磁场大小而变化;而且冷头电机本身是永磁电机,电机性能受磁场影响更明显.因此,为了不影响制冷机的性能,需要详细地分析制冷机附近的磁场分布,将制冷机布置在低场区域;但是,高场磁体系统本身磁场强度高、温度裕度低,为了降低磁体运行时的热点温度,不可能将制冷机布置在距离磁体较远的区域,这时就需要对制冷机采取屏蔽措施.本文以正在建造的8T传导冷却超导磁体系统为例,研究了磁场对制冷机位置的影响,并分析了铁磁屏蔽对制冷机附近磁场的屏蔽效果.GM cryocoolers for conduction-cooled superconducting magnet system are exposed in high magnetic field. The specific heat of magnetic regenerator material for 4 K GM cryocooler is affected by external magnetic field at low temperature. And the performance of cold-head motor is also affected for its permanent magnet. Thus the high magnetic field will degrade the cooling capacity of cryocoolers. It is necessary to analyze the magnetic distribution near the cryocoolers and make them located in low magnetic field. In order to reduce the temperature difference from the hot spot of magnet to the second stage, the cryocoolers should not be far from superconducting magnet. They may be in high magnetic field for some superconducting magnet system. So magnetic shielding for the cryo- coolers should be installed to reduce the magnetic flux from superconducting coils. Effects of magnetic field on the performance of GM cryocoolers were presented in this paper. Then the magnetic field around the cryocoolers used for 8 T conduction-cooled superconducting magnet is analyzed. At last, motor shielding for this magnet is studied by Opera software.

关 键 词：传导冷却超导磁体 GM制冷机 外磁场 磁屏蔽 

分 类 号：TM265[一般工业技术—材料科学与工程]