Wall-conditioning plasmas by ECRF heating in KSTAR

KSTARにおけるECRFによる壁調整プラズマ

伊丹 潔; Hong, S.-H.*; Bae, Y.-S.*; 松川 誠; Kim, W.-C.*; KSTAR Team*

Itami, Kiyoshi; Hong, S.-H.*; Bae, Y.-S.*; Matsukawa, Makoto; Kim, W.-C.*; KSTAR Team*

The plasma experiments to investigate the production of the helium ECWC plasmas and wall cleaning effects were carried out in the campaigns in 2010 and 2011 of KSTAR. Pulses of ECRF heating with fECRF = 110 GHz were injected into the vacuum vessel and the production of the ECWC plasma was measured by the plasma diagnostics. In 2010, the second harmonic of ECRF heating was applied at the position of = 1.97 . It was found that the ECRF injection vertical to the toroidal field, was essentially important to produce high density plasmas and the uniformity of the plasma is significantly changed by field pattern of and . In 2011, the fundamental ECRF heating was applied at the position of = 3.94 . It was demonstrated that a reference tokamak discharge successfully started up the plasma current after the wall conditioning by ECRF.