X-ray Measurements during Plasma Current Start-up Experiments using the Lower Hybrid Wave on the TST-2 Spherical Tokamak

• DOI: 10.1541/ieejfms.132.485
• Publication Date: 2012-06-30T22:43:14Z
• Authors: Takuma Wakatsuki; Akira Ejiri; Hidetoshi Kakuda; Yuichi Takase; Takanori Ambo; Hirokazu Furui; Takahiro Hashimoto; Junichi Hiratsuka; Hiroshi Kasahara; Kunihiko Kato; Ryuhei Kumazawa; Yoshihiko Nagashima; Kenji Saito; Takuya Sakamoto; Tetsuo Seki; Fujio Shimpo; Ryota Shino; Takahiro Shinya; Masateru Sonehara; Osamu Watanabe; Takashi Yamaguchi; Charles P. Moeller
• Keywords: Lower hybrid oscillation; Electron temperature

Non-inductive plasma current start-up experiments using RF power in the lower hybrid frequency range is being conducted on TST-2 spherical tokamak. Plasma currents of up to 15 kA have been achieved. The effect direct drive can be seen by comparing cases with co-drive and counter-drive. X-rays various energy ranges were measured investigate interaction between wave electrons. Soft X-ray (SX) measurements revealed that perpendicular SX emission increased significantly as increased, tangential direction was enhanced more strongly case compared counter-drive case. These observations imply fast electrons accelerated contribute current. However, amplitude modulation showed confinement time these are very short (less than 0.05 ms), much shorter collisional slowing down time. Hard spectral radiation temperature co-direction for higher counter-direction. consistent existence RF-driven