Transient electric field Distribution in 1MV DC GIL for ITER Neutral Beam Injector

In this paper, the simulation model is developed to investigate the transient electric field (E-field) distribution in 1 MV DC GIL for ITER neutral beam injector (NBI) considering the peculiar operating conditions in NBI i.e. a square wave voltage and radiation induced conductivity. The results show that the E-field distribution is constantly changing due to the particular NBI voltage waveform, which greatly increases the difficulty of design of GIL. In addition, an increase of surface charge accumulation and an increase of the E-field near the shell is found due to the SF6 radiation induced conductivity. This paper aims to offer a reasonable insulation design reference for the safe and stable operation of the ITER.