Simulation of heat transfer performance of NBI transmission line

During the working period of the ion source of a Neutral Beam Injector (NBI) for plasma heating, the temperature of its transmission line inserted in its snubber rises rapidly. This is because the heating current of the filament and arc reaches over 10 kA for over 100 s, which accumulates large amounts of energy on the line. Rapidly ageing of the wire insulation will occur as the temperature rises. More importantly, an electrical fire could occur in a case of poor design. In this paper, the heat transfer performance of a neutral beam transmission line is analysed using Computational Fluid Dynamics (CFD) software, which is operated by the mode of repetitive pulse. The temperature distribution of the transmission line, inserted in the snubber, is obtained after a number of pulse cycles by numerical simulation and the results provide a reliable basis for the design of Experimental Advanced Superconductor Tokamak (EAST) NBI power transmission lines.