Heat generation and cooling optimization of the superconducting coils for JT-60SA

Kamiya, Koji; Murakami, Haruyuki; Kizu, Kaname; Ichige, Toshikatsu; Yoshida, Kiyoshi

JT-60SA project replaces the JT-60U tokamak with a full superconducting tokamak. The helium refrigerator cools the superconducting coils by circulating 4.4 K, 0.6 MPa supercritical helium 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, estimation of the heat generation and required mass flow rate to acquire sufficient temperature margin is of crucial importance. In this paper, optimizing the mass flow rate in the superconducting coils was attempted to satisfy 1 K temperature margin. Then, it is shown that the consequent maximum pressure drop in the circulation loop is 81 kPa to result in minimizing the heat load of the supercritical helium circulation pump.