Heat Generation and Cooling Optimization of the Superconducting Coils for JT-60SA

Abstract

Synopsis:In the JT-60SA project, the JT-60U tokamak is replaced with a full superconducting tokamak. The helium refrigerator cools the superconducting coils by circulating supercritical helium of 4.4 K and 0.6 MPa in the circulation loop at certain mass flow rate. Since the cooling power of the helium refrigerator is determined by the heat load of the superconducting coils, estimating the heat generation and required mass flow rate to acquire sufficient temperature margin is of crucial importance.In this paper, we attempted to optimize the mass flow rate in the superconducting coils to satisfy a temperature margin of 1 K. We then show that the consequent maximum pressure drop in the circulation loop that results in minimizing the heat load of the supercritical helium circulation pump is 81 kPa.