Properties of thin boron coatings formed during deuterated-boronization in JT-60

• Published in: Journal of nuclear materials 1997-02, Vol.241-243 (1), p.579-584
• Main Author: Yagyu, J
• Format: Article
• Language: English
• ISSN: 0022-3115
• DOI: 10.1016/S0022-3115(96)00568-5

Since 1992, the boronization using B10H14 (decaborane-based boronization) has been utilized in JT-60 once or twice a year. It is very effective in reducing both the impurities, like oxygen and carbon, in the plasma and in recycling fuel particles. However, we needed approx 500 discharges to exchange hydrogen in the boron film for deuterium, after the boronization using only He for a dilution gas. Using a mixed-dilution gas of He and deuterium, we made the boronized film on JT-60 first wall (deuterated-boronization). A typical composition of working gas was 2% B10H14, 38% D2 and 60% He, which was used in a flow through situation. The amounts of hydrogen and deuterium in the boronized film were evaluated to be approx 5 and approx 30 at%, respectively. In addition, the deuteration factor of D(H + D) in the first plasma after the boronization increased from less than 0.2 to 0.8. Thus, we can drastically reduce the number of the conditioning discharges from approx 500 to approx 50 for the isotope-exchange before D plasma experiments.