High power heating and current drive in JT-60

Abstract

Advances of JT-60 experiments in current drive and high power heating are presented. Fully noninductive current drive of 2 MA is achieved by LHRF without OH assistance. Thecurrent drive efficiency ηCD, defined as n-bare(1019 m-3)IRF(MA)Rp(m)/PLH(MW), is in the range0.8 - 1.7 and is improved to 1.7 - 3.0 when NB heating is applied to the LHCD plasma.Confinement improvement is also obtained when LHCD and NB heating are combined. TheMHD fluctuations in the central plasma region of such a discharge are suppressed by a factor of 10 compared to the case of NB heating only. In the electron heating mode of LHRF,Te(0) of 6±1 keV is obtained with a high heating efficiency of 2- 3 × 1019 keV/MWm3, andL-mode-like behavior is seen in the energy confinement in such plasmas. High iontemperatures of Ti(O) = 11 ± 2 keV are attained in hydrogen plasmas at densities ofn-bare = 2 - 3 × 1019 /m3 with NB heating. Substantial beam acceleration is observed when NB andICRF heating are combined. Charge exchange neutral spectra show that high energy ion tailof up to at least 160 keV is generated compared to the NB acceleration voltage of 60 kV.