High harmonic fast wave heating and beam driven ion cyclotron emission behavior in the LHD

"Central electron heating with 40 % of heating efficiency is achieved by the use of high harmonic fast wave (HHFW) in the large helical device (LHD), and a substantial electron heating is observed in the central region of the plasma due to the synergy effect of ECH and HHFW. On the other hand, in high ion temperature aimed discharge ion cyclotron emissions (ICEs) are clearly detected using ion cyclotron heating antennas as a magnetic fluctuations, and the damped mechanism of ICEs is similar to that of HHFW. Observed magnetic fluctuations are rapidly increased after parallel NB is injected, and the excitation effect of ICEs seems to be different between fundamental and multi-harmonic ICEs in the direction of parallel NBI. When parallel NBI to counter direction is stopped, decay time of the fundamental ICE intensity is obviously longer than those of the higher harmonic ICE intensities.