Abstract
An electron cyclotron range of frequency (ECRF) programhas been initiated to study the local heating and current drivein JT-60U. A frequency of 110 GHz was adopted to couple thefundamental O-mode from the low-field side with an oblique toroidalinjection angle for the current drive. Experiments were performed atan injection power of ~1.5 MW by using three gyrotrons,each of which has generated the output power up to ~0.8 MWfor 3 seconds. A strongly peaked Te profile was observed andthe central electron temperature increased up to ~15 keVwhen the O-mode was absorbed on the axis. The local electron heatingclarified the significant difference in the heat pulsepropagation between in the plasmas with internal transportbarrier (ITB) and without. The driven current estimatedby the Motional Stark Effect (MSE) diagnostic showed that theelectron cyclotron (EC) waves drove the plasma current up to~0.2 MA for an injected power of ~1.3 MW at thelocal electron temperature and density of Te~6keV, ne~0.7×1019 m-3. The measured drivencurrent near the axis was consistent with the theoreticalprediction using a Fokker-Planck code. In the case of co-electron cyclotron current drive (ECCD), the sawtooth activityin neutral beam (NB) heated plasma was completely suppressed for1.5 s with the deposition at the inversion radius, while thesawtooth was enhanced for counter-ECCD at the same depositioncondition.
Published Version
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