Numerical investigation on the steady temperature rise of a by-pass switch

Abstract The quench protection switch (QPS) is very important for ensuring the safety of the magnet coils of a superconducting Tokamak. The main function of a QPS is to protect the magnet as the coil quench occurs. Besides, a QPS has to withstand almost all of the coil current of some tens of kA flowing through it in the normal operation condition. This task is undertaken by the by-pass switch (BPS), which is an indispensable component of a QPS, no matter what principle the QPS is based on. Therefore, the study of the temperature rise is very important for optimal design of a BPS. In this paper, a scheme of a high-current BPS is proposed. The steady temperature rise of the BPS is simulated in the condition of natural convection with the approach of Computational Fluid Dynamics (CFD). Furthermore, the influence of the space between each individual switch unit is investigated. Simulation results indicate that there exists an appropriate space, beyond which the mutual influence of adjacent contacts can be accepted. This space can be regarded as a reference in designing a BPS with the trade-off between the dimension of the BPS (and the QPS) and its current-carrying capacity.