Characteristics of a high density cloud ablated from an ice pellet in the JIPP T-IIU tokamak plasma

Characteristics of a cloud ablated from an ice pellet has been investigated in detail in the JIPP T-IIU tokamak by ''an injection-angle controllable system''. A long ''helical tail'' of ablation light has been observed by using CCD cameras and a high speed framing photograph. Spectroscopic measurements have been carried out in order to have informations on the parameters in the ablation cloud. The relation of ablation behavior with plasma potential and rotation has also been studied by using heavy ion beam probe (HIBP) method. From the experimental results and considerations, the ''tail'' structure may be caused both by the situation of charge exchange equilibrium of hydrogen ions and neutrals at extremely high density regime in the cloud, and by the effect of the plasma potential and the rotation. (author)