Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
The first measurement of the current profile driven by the fundamental X-mode electron cyclotron (EC) waves launched from the low field side is presented. Such X-mode waves can couple to electrons with large velocity in a high temperature plasma due to the Doppler shift effect, in a properly low density condition. The 110GHz EC waves of about 1MW are launched into the JT-60U tokamak, with changing power fraction of the O/X-mode component. The driven current profile is evaluated, considering transient toroidal electric field profile measured by the motional Stark polarimetry. Preliminary analysis shows that the current drive layer of the X-mode waves is narrower and that the current drive efficiency is larger (by a factor of 1.5) than that of the O-mode waves, where line averaged electron density was n_e = 0.4 \times 10^19 m^-3 and local electron temperature was T_e = 4-5 keV. The X-mode waves could not be absorbed in a higher density plasma of n_e = 1 \times 10^19 m^-3. The results are consistent with those of the ray-tracing and the Fokker-Planck calculations.