Recent progress of the high power ECRF system on JT-60U
Masami SEKI, Shinichi MORIYAMA, Ken KAJIWARA, Yoshitaka IKEDA, Keishi SAKAMOTO, Tsuyoshi IMAI and Tsuneyuki FUJII
Japan Atomic Energy Research Institute, Ibaraki, 311-0193, Japan
Abstract.
The Electron Cyclotron Range of Frequency (ECRF) system having four 1 MW身yrotrons has been successfully operated on JT-60U to locally heat a plasma and drive a plasma current. After modification by suppressing a parasitic oscillation, the gyrotron can generate ~1.1 MW for 3.2 s. High RF powers generated by four gyrotrons are transmitted to two independent antennas consisting of steerable mirrors via four long transmission lines with high transmission efficiency of 70-80 %. In 2001, injected power reaches up to ~2.8 MW for 2.8 s after optimizing operational parameters. In such high power injection, a substantial increment in central electron temperature from 5 keV up to ~13 keV is observed in the Reverse-Shear (R-S) plasma with the Internal Transport Barrier (ITB).