High power ICRF heating experiment in LHD

Heating experiment using high-power ion cyclotron range of frequency (ICRF) waves has been carried out and remarkable results as an ICRF heating in helical system were obtained in LHD. The maximum ICRF power was 2.7 MW. Good he0ating condition was obtained when the ion cyclotron resonance layer was located near the saddle point of the magnetic field. In this condition, the wave frequency is 38.47 MHz and strength of magnetic field is 2.75 T. Most of ICRF power was absorbed by ions and behavior of high-energy ions was investigated in the various heating conditions. The stored energy more than 1 MJ was achieved by combination of the ICRF heating with NBI heating. Fundamental cyclotron heating was observed in the high stored energy experiment. Second harmonic heating regime was shown to be useful heating scheme in LHD. The length of the ICRF pulse was extended to more than two minutes in the low power operation.