High frequency ion Bernstein wave heating experiment in the JIPP T-IIU tokamak

An experiment in a new regime of ion Bernstein wave (IBW) heating was carried out using 130 MHz high power transmitters in the JIPP T-IIU tokamak. The heating regime utilized the IBW branch between the 3rd and 4th harmonics of the hydrogen ion cyclotron frequencies. This harmonic number is the highest one used in IBW experiments conducted previously. The net radiofrequency (RF) power injected into the plasma is around 400 kW and is limited by the transmitter output power. Core heating of ions and electrons was confirmed in the experiment and density profile peaking was found to be a special feature of IBW heating. Peaking of the density profile was also found when IBWs were injected into neutral beam heated discharges. An analysis, using a transport code with these experimental data, indicates that particle and energy confinement should be improved in the plasma core region upon application of IBW heating. It is also found that the ion energy distribution function observed during IBW heating has a smaller high energy tail than those observed in conventional fast magnetosonic wave ICRF heating regimes. The ion energy distribution function obtained during IBW heating is in reasonable agreement with that calculated using the quasi-linear RF diffusion/Fokker-Planck model