Details

Autor(en) / Beteiligte

• TAKAHASHI, Hiromi
• OSAKABE, Masaki
• MURAKAMI, Sadayoshi
• NAGAOKA, Kenichi
• NAKANO, Haruhisa
• TAKEIRI, Yasuhiko
• SEKI, Tetsuo
• SAITO, Kenji
• KASAHARA, Hiroshi
• KAMIO, Shuji
• MUTOH, Takashi
• Group, the LHD Experiment

Titel

High Ion Temperature Plasmas using an ICRF Wall-Conditioning Technique in the Large Helical Device

Ist Teil von

• Plasma and Fusion Research, 2014/05/07, Vol.9, pp.1402050-1402050

Ort / Verlag

The Japan Society of Plasma Science and Nuclear Fusion Research

Erscheinungsjahr

2014

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• A new effective wall-conditioning technique was proposed for realizing high ion temperature (Ti) plasmas in the Large Helical Device using the ion cyclotron range of frequency (ICRF) wave under the established magnetic confinement field. A series of ICRF heating discharges using He as the working gas was conducted ahead of the high-Ti plasma discharges. After sufficient repetitive wall-conditioning discharges, we observed a decrease in the line-averaged electron density, the formation of a peaked electron density profile, a reduction in the Hα emission, and an increase in the central Ti. The results suggest that the stored hydrogen inside the vacuum vessel structures, such as the first wall, the diverter, and other components, sputtered out owing to the He plasmas of the ICRF wall-conditioning discharges and the hydrogen recycling was decreased. Consequently, the ion heating power of NBI increased in the plasma core region, leading to higher central Ti.