Present status and one upgrading method with a cold compressor of the EAST sub-cooling helium cryogenic system

• Published in: Plasma science & technology 2017-05, Vol.19 (5), p.102-108
• Main Author: 朱志刚 张启勇 宋云涛 庄明 周芷伟 成安义 朱平
• Format: Article
• Language: English
• Subjects: cold compressor; cryogenic system; EAST; EAST装置; helium refrigerator; sub-cooling helium; 低温制冷系统; 冷却系统; 冷压机; 升级方法; 实验测试; 超临界氦; 超导托卡马克
• ISSN: 1009-0630; 1009-0630
• DOI: 10.1088/2058-6272/aa58da

Since 2006, the superconducting toroidal field（TF） coils of the Experimental Advanced Superconducting Tokomak（EAST） have been successfully cooled by supercritical helium at a temperature of 4.5 K and a pressure of 4 bara in eleven experiments. To obtain higher operating currents and magnetic fields it is necessary to lower the operating temperature of the TF coils.The EAST sub-cooling helium cryogenic system, with a warm oil ring pump（ORP）, was tested twice in cool-down experiments, which made the TF coils operate at 3.8 K. However, the long term operational stability of the sub-cooling system cannot be guaranteed because of the ORP＇s poor mechanical and control performance. In this paper, the present status of the EAST subcooling helium cryogenic system is described, and then several cooling methods below 4.2 K and their merits are presented and analyzed. Finally, an upgrading method with a cold compressor for an EAST sub-cooling helium cryogenic system is proposed. The new process flow and thermodynamic calculation of the sub-cooling helium system, and the main parameters of the cold compressor, are also presented in detail. This work will provide a reference for the future upgrading of the sub-cooling helium system for higher operation parameters of the EAST device.