Optimization of the thermal shielding design of a temperature gradient type thermal probe

In order to improve the temperature gradient type thermal probe (GTP) for low density plasma, simulation study with XOOPIC code was made. Considering the sheath stability condition found in 1D sheath study, simulation model for complicated 2D geometry was constructed and found it possible to increase the gap between the thermal shield and the probe tip. By using this result, a glass GTP was constructed. Unfavorable radial conductive heat transport was found to be reduced to negligible level and the effect radial convective heat transport was estimated. Plasma heat flux changes due to discharge change were monitored with this improved GTP.