ECRF experiments for local heating and current drive by fundamental O-mode launch from the low-field side on JT-60U

• Published in: Nuclear fusion Vol. 42; no. 4; pp. 375 - 382
• Main Authors: Ikeda, Y, Ide, S, Suzuki, T, Kasugai, A, Takahashi, K, Kajiwara, K, Isayama, A, Oikawa, T, Hamamatsu, K, Kamada, Y, Fujita, T, Sakamoto, K, Moriyama, S, Seki, M, Yoshino, R, Imai, T, Ushigusa, K, Fujii, T, Team, JT-60
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.04.2002; Institute of Physics
• Subjects: Carrier concentration; Current density; Cyclotrons; Electric fields; Electrons; Exact sciences and technology; Gyrotrons; Magnetic confinement and equilibrium; Magnetic fields; Optimization; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma heating (beam injection, radio-frequency and microwave, ohmic, icr, ecr and current drive heating); Plasma production and heating; Spectroscopic analysis; Tokamak devices; Tokamaks; Electron cyclotron frequency; Plasma; Electron cyclotron wave; Stark effect; Experimental study; Plasma diagnostics; Magnetic confinement; Gyrotrons; MHD instability; Confined plasma; ECR heating; JT-60U tokamak; Plasma heating
• ISSN: 0029-5515; 1741-4326
• DOI: 10.1088/0029-5515/42/4/301

An electron cyclotron range of frequency (ECRF) program has been initiated to study the local heating and current drive in JT-60U. A frequency of 110 GHz was adopted to couple the fundamental O-mode from the low-field side with an oblique toroidal injection angle for the current drive. Experiments were performed at an injection power of ~1.5 MW by using three gyrotrons, each of which has generated the output power up to ~0.8 MW for 3 seconds. A strongly peaked T e profile was observed and the central electron temperature increased up to ~15 keV when the O-mode was absorbed on the axis. The local electron heating clarified the significant difference in the heat pulse propagation between in the plasmas with internal transport barrier (ITB) and without. The driven current estimated by the Motional Stark Effect (MSE) diagnostic showed that the electron cyclotron (EC) waves drove the plasma current up to ~0.2 MA for an injected power of ~1.3 MW at the local electron temperature and density of T e ~6 keV, n e ~0.7×10 19  m -3 . The measured driven current near the axis was consistent with the theoretical prediction using a Fokker-Planck code. In the case of co-electron cyclotron current drive (ECCD), the sawtooth activity in neutral beam (NB) heated plasma was completely suppressed for 1.5 s with the deposition at the inversion radius, while the sawtooth was enhanced for counter-ECCD at the same deposition condition.