Study of Hydrogen Ice Pellet Ablation During EC and NBI Heating in GAMMA-10

Refueling by hydrogen ice pellet injection has been studied in various plasmas. The research of pellet ablation related to refueling is very important object. In the central-cell plasma of tandem mirror GAMMA 10, we measured the position of pellet ablation by vertical and horizontal arrays of H detectors and a high-speed CMOS camera. We found that the penetration depths with applying electron cyclotron heating (ECH) is shorter than that without ECH. It suggests that the pellet ablation is strongly affected by warm electrons produced with ECH. Moreover, we investigated the effects of neutral beam injection (NBI) to the pellet ablation, which showed the pellet ablation in the situation of higher density plasma. The pellets penetrate through the plasma without applying ECH or NBI. We observed the pellet ablation at each position by using vertical and horizontal arrays of H detectors and a high-speed CMOS camera with the interference filter.