Non-linear core plasma response to ICRF heating with transport

A steady state, three-dimensional, Fokker-Planck code, RFTRANS, has been developed that includes real-space radial diffusion at the kinetic level as well as models of auxiliary heating. The RFTRANS code has been coupled with the one-dimensional full-wave code ORION-S which calculates the electric fields and power absorption profiles for waves in hot plasmas in the ion cyclotron range of frequencies (ICRF). The differences between fast wave (FW) absorption and ion Bernstein wave (IBW) absorption by a minority plasma species have been studied, using simple models to map the ORION-S power profiles into cylindrical geometry. The effects of the absorbed ICRF power are calculated by the RFTRANS code, and the resulting minority distribution function is decomposed into two Maxwellian distribution functions at each radial location for input into the dispersion relation used by the ORION-S code. The process is iterated until convergence is reached. There is a significant difference between the effects of FW absorption and the effects of IBW absorption in velocity space which is due to the differences in perpendicular wavelength. When a simple kinetic real-space diffusion coefficient is used, the strong gradients in the heated minority distribution function are relaxed and the absorption profiles are affected. The results indicate that the application of high power fast waves launched from the low field side into a hydrogen minority/deuterium majority plasma can cause a strong shift of the radial absorption peak towards the antenna structure. Thus, at high power levels, the absorption becomes peaked near the magnetic axis when the ion cyclotron resonance is on the high field side of the magnetic axis; this is due to the combined effects of the radial diffusion of the hot tail components of the distribution function and the Doppler shift of the resonance.