Results of ITER DMS Pellet Material (Neon) Injection into Large Helical Device

Abstract

Cryogenic neon pellets of 3 mm in diameter were injected into neutral beam injection (NBI) heated discharges on the Large Helical Device (LHD). The time response of far infrared (FIR) interferometer has pointed out a relatively slow assimilation of the ablated materials compared to the cases of hydrogen injection. This is consistent with the neutral gas and plasma shielding (NGPS) model prediction, showing that strong line emission inside the ablation cloud limits the cloud temperature and the expansion velocity along the magnetic field line. Measured penetration depths were also compared, being well reproduced by the code prediction when the contribution from 180 keV fast ions produced by tangential NBI is taken into account.