上海电子束离子阱低温超导磁体系统的研制

Design and manufacture of cryogenic and superconductor system for Shanghai Electron Beam Ion Trap

介绍了上海电子束离子阱(Electronbeamiontrap,EBIT)装置低温超导磁体系统的研制过程和测试结果。超导磁体由一对上下布置的Helmholtz线圈组成,中心最大磁场强度可达5.3T,两线圈的峰值磁场偏差小于3×10-4T,在中心轴线上±10mm内磁场均匀度好于2×10-4,磁场衰减率在8h内小于1×10-4。低温系统采用双冷屏结构,通过二级G-M制冷机冷却冷屏来降低液氦的蒸发量。系统液氦灌注达到平衡后,液氦的平均蒸发量为1.1L/h,基本满足了用户的要求。

Design and manufacture of the cryogenic and superconductor system for Shanghai Electron Beam Ion Trap （EBIT） have been reported in this paper. The adopted measures to improve the system＇s performance and experiment results are also described. In order to reduce the consumption of liquid helium, the cryogenic system includes two cooling-shields cooled by two stage G-M refrigerator. The consumption of liquid helium is 1.1 L/h on average in 16 h, the peak of magnetic field strength of superconducting magnet is up to 5.3 T, uniformity is better than 2×10^-4 in the range of ＋10 mm on the central axis of magnet, and the time decaying ratio of magnet is better than 1 ×10^-4 in 8 h with closed-loop current. All these show that user＇s basic demands can be met.