Analysis of residual gas by high-resolution mass spectrometry during helium glow discharge cleaning in JT-60U

高分解能質量分析装置を用いたヘリウムグロー放電洗浄中のJT-60U残留ガス分析

林 孝夫; 神永 敦嗣; 新井 貴; 佐藤 正泰

Hayashi, Takao; Kaminaga, Atsushi; Arai, Takashi; Sato, Masayasu

高分解能質量分析装置を用いて、JT-60U残留ガスの質量分析を行い、ヘリウムグロー放電洗浄(He-GDC)の効果を調べた。質量分析の分解能が高くDとHeの弁別が可能な質量分析装置を今回新たに導入した。He-GDCの開始後、Dガスの分圧が上昇し、最大分圧(3.810Pa)に到達した。これはHe-GDC開始前(3.510Pa)の約十倍の圧力であった。7時間のHe-GDC中に放出されたDガスの量は、4Pa mであった。He-GDC終了後、Dガスの分圧はHe-GDCの前よりも下がり、He-GDC(7時間)+約7時間経過後には5.710Paに到達した。これらの結果からHe-GDCがプラズマ対向機器の重水素除去に有効であることがわかった。

The residual gas analysis has been conducted by high-resolution mass spectrometry which can discriminate between D and He gas species during helium glow discharge cleaning (He-GDC) in JT-60U in order to investigate the effect of He-GDC. The residual gas analyzer was able to distinguish between D and He peaks during He-GDC. Since the He-GDC started, the partial pressure of D gas increases with time and reached its highest pressure (3.8 10 Pa), which is about ten times larger than that before the He-GDC (3.5 10 Pa). The total amount of D, which was released during the He-GDC (7 hours), was evaluated as 4 Pa m. The pressure of D (5.7 10 Pa) about 7 hours after the He-GDC (7 hours) is significantly lower than before the He-GDC, which indicates the He-GDC is effective to remove the deuterium from plasma facing components.