Reproducible H-mode plasmas with electron cyclotron (EC) waves as the sole auxiliary heating tool have been achieved recently on EAST in a broad range of plasma parameters with an ITER-like tungsten divertor. The macroscopic characteristics of H-mode in the terms of the global energy confinement, the threshold of heating power and plasma density for the L–H transition are presented. The enhanced confinement factor H98(y,2) is around 1.0 in most cases, but it can be up to 1.25 for some discharges. Dedicated EC current drive (ECCD) experiments were performed in L-mode plasmas with relatively low density and the EC current (IEC) has been determined unambiguously on EAST for the first time. The measured EC current reaches 83 kA, representing about 1/3 of the total plasma current and corresponding to a CD efficiency (ηCD) ∼ 0.15 (1019 AWm−2). The experimental ECCD results are analyzed with both the ray-tracing and Fokker–Planck codes. It is found that the EC driven current is underestimated by the linear ray-tracing code TORAY-GA to some extent, and is overestimated by the quasi-linear Fokker–Planck modeling with LUKE in low density and high EC power plasmas.
This paper reports the achievement of stable H-mode plasmas using only electron cyclotron (EC) waves as auxiliary heating on the EAST tokamak. It presents the key characteristics of the H-mode, such as energy confinement and L-H transition. The paper also describes successful experiments on EC current drive, which generated a significant fraction of the total plasma current.