[1L01-03] Fusion Engineering

[1L02] Reduction of hydrogen recycling using boron powder in LHD

*Naoko Ashikawa^1,2, Tomoko Kawate^1,3,2, Hirotaka Toyoda^4,1, Zhen Sun^5,6 (1. National Institute for Fusion Science, 2. The Graduate University for Advanced Studies, 3. National Astronomical Observatory of Japan, 4. Nagoya University, 5. Institute of Plasma Physics, Chinese Academy of Sciences, 6. Princeton Plasma Physics Laboratory)

Keywords:Fusion plasma, hydrogen recycling, real-time control, boron, LHD

Since hydrogen isotope trapping by boron may contribute to wall recycling controls, analytical data of hydrogen isotope is important. In LHD, a new impurity powder dropper (IPD) system was installed and we had experiments of a real-time interactions between boron and hydrogen.
In the IPD system, boron (B) powders are dropped into plasmas, and the amounts and timings of boron powder injections can be controlled, reduction of hydrogen Balmer lines were observed just after B powder attaching to plasmas. This time scale is shorter than boron coatings on the wall. Hence, real-time interactions at edge plasma for a reduction of hydrogen recycling is considered. In this talk, real time control mechanism and initial experimental results are shown.