19th IAEA Fusion Energy Conference

Heating and Current Drive by Electron Cyclotron Waves in JT-60U

T.Suzuki¹⁾, S.Ide¹⁾, C.C.Petty²⁾, Y.Ikeda¹⁾, K.Kajiwara¹⁾, A.Isayama¹⁾, K.Hamamatsu¹⁾, O.Naito¹⁾, M.Seki¹⁾, S.Moriyama¹⁾ and the JT-60 Team¹⁾
1) Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Ibaraki 311-0193, Japan
2) General Atomics, San Diego, California, US

Abstract.
Results of studies on heating and current drive by the electron cyclotron (EC)waves in JT-60U are presented.Electron temperature up to 26keV was achieved by injecting EC waves in the center of a reversed shear plasma produced by the lower hybrid (LH)waves. The electron temperature T_e exceeds 24keV in a wide range of minor radius (ρ < 0.3, where ρ is the normalized minor radius). ECCD (Current Drive) efficiency η_CD was examined at high T_e up to 21keV without using LH waves. The CD efficiency increases with T_e, but there is discrepancy from linear dependence on T_e in a high T_e regime of 10-20keV. Dependence of normalized CD efficiency ζ=e³η_CD/ε₀²kT_e on deposition location was also studied to optimize the CD efficiency, since trapped particle effect, which depends strongly on deposition location, is expected to reduce ζ. The effect was detected from significant decrease in ζ in the lower magnetic field deposition,which is consistent with linearlized Fokker-Planck calculation.