Hydrogen removal via ICRF technique on HT-7 - experiment and modeling on neutral energies

Hydrogen removal experiment in HT-7 is briefly reported. The modeling effort by a Monte-Carlo transport code, DEGAS 2, was made to elucidate the energies of hydrogen neutrals in the HT-7 RF plasmas. Concentration was paid on the Balmer line emission. The modeling results reveal that the neutral hydrogen atoms in the range of 10-20 eV occupy a high fraction and they could be easily removed. This could be one of the reasons for the easy hydrogen removal via RF technique in HT-7 cleaning. The scheme with RF power at about 10 kW and the deuterium working gas at a pressure about 0.01 Pa, could be an optimized scheme for hydrogen removal