Characteristics of pellet ablation in high temperature plasmas

Summary form only given, as follows. Characteristics of a cloud ablated from an ice pellet has been investigated in detail in the JIPP T-IIU tokamak plasma by utilizing a new scheme of pellet injection system, the injection-angle controllable system. A long helical tail of ablation light has been observed by using CCD cameras and a high speed framing photograph in the case of on-axis and off-axis injection with the injection angle smaller than a certain value. The direction of helical rotation (tail) is found to be independent to that of the total magnetic field lines of the torus. From the experiments with the combination of two (CW and CCW) toroidal field directions and two plasma current directions, it is concluded that the tail seems to rotate, in most cases, to the electron diamagnetic direction poloidally, and to the opposite to the plasma current direction toroidally.