Heat Transfer Analysis of MgB2 Coil in Heat Treatment Process for Future Fusion Reactor

Abstract

State of the art MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is reviewed as a potential material for the poloidal field (PF) coils of the future fusion reactor due to its high critical temperature and low material cost. The heat treatment process is a crucial step in the development of MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> magnets. The temperature lag in heat treatment of large magnets can lead to insufficient thermal reaction time. It may be infeasible to control the temperature of a magnet according to the heat treatment scheme recommended for the MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wire. Hence, the heat treatment process of a large magnet needs to be evaluated. Therefore, the dynamic temperature distribution of a MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> PF coil is obtained by simulating the heat transfer in heat treatment process. A suitable heat treatment schedule for a large magnet is proposed and the experimental results of a sub-size Cable-In-Conduit Conductor manufactured with MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> strand confirmed the feasibility of the newly proposed heat treatment process. The results provide a reference for the heat treatment method of a future larger MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> coil.