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

Abstract

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.

Optimal design of the first stage of the plate-fin heat exchanger for the EAST cryogenic system

“…As shown in figure 1, the EAST helium cryogenic system mainly consists of a compressor station, cryogenic distribution system and cold box [18]. Seven stages of the PFHEthree turbine expanders, cryogenic absorber and filter, cryogenic valves, etc-are installed in the vertical cold box.…”