Heat transfer analysis during heat treatment of Nb3Sn coils for the CFETR CSMC

Abstract

The heat treatment of Nb3Sn coils of China Fusion Engineering Test Reactor (CFETR) central solenoid model coil (CSMC) has been completed at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The brittle A15 phase material requires coil winding prior formation of the superconducting material, and the technology of “wind and react” has been used to manufacture Nb3Sn coil. The Nb3Sn coils were heat-treated under the argon atmosphere and the heat treatment was successful. Since the critical properties of Nb3Sn strongly depend on the heat treatment temperature, especially the uniformity of temperature, it is necessary to analyze the detailed temperature change process during the heat treatment. During the heat treatment, several thermocouples were arranged on the coil surface for temperature monitoring. At the same time, the heat transfer process of heat treatment and the distribution of the coil temperature field is theoretically analyzed and simulated. The uniformity of heat treatment temperature meets the requirements. This paper mainly presents the heat transfer analysis, heat treatment process, and numerical simulations during heat treatment.