[2L17-18] Plasma Engineering

[2L17] Reduction of hydrogen wall recycling using boron powder in LHD

*Naoko Ashikawa^1,2, Tomoko Kawate^1,2,3, Zhen Sun⁴, Chenglong Li⁵ (1. National Institute for Fusion Science, 2. The Graduate University for Advanced Studies, SOKENDAI, 3. National Astronomical Observatory of Japan, 4. Princeton Plasma Physics Laboratory, 5. Institute of Plasma Physics, Chinese Academy of Sciences)

Keywords:fusion plasma, hydrogen reduction, LHD

Boron has the advantage for hydrogen trapping in the plasma vacuum vessel, in general. In LHD, the impurity powder dropper (IPD) system was installed and had experiments of real-time interactions between boron and hydrogen isotope plasmas. In plasma experiments after the boron powder dropping by IPD, it was observed that a reduction of oxygen and hydrogen isotopes. Obtained data shows that coated boron layers on the plasma-facing areas by IPD experiments, and plasma parameters of boron impurities and hydrogen with a quick response when boron particles reached plasmas. But details of interactions between hydrogen isotopes and boron are not clear. In this presentation, new experimental data about hydrogen-boron interactions in hydrogen isotope plasma discharges is presented in LHD.