Numerical analysis on effect of Kapitza conductance on stability of LHD conductor cooled by He II

Abstract

An analytical code to simulate the dynamic one-side propagation of a normal zone observed in the LHD conductor was developed. The dynamic one-side propagation phenomenon is the one in which a short normal zone initiated by a thermal disturbance dynamically propagates only to one side along the conductor and shrinks after a few seconds. This code was based on the two-dimensional heat balance equation, current diffusion ones, Hall effect and database on the cooling properties of He II. Using the proposed code, numerical analyses were performed on two LHD conductors with different surface conditions (oxidized and polished). The asymmetrical propagation phenomenon was successfully simulated. The analytical results showed that the stability of the LHD conductor becomes better with making Kapitza conductance large. One of the main factors that govern the stability of the LHD conductor cooled by He II is Kapitza conductance.