Effective temperatures, sawtooth mixing, and stochastic diffusion ripple loss of fast H+ minority ions driven by ion cyclotron heating in the TokamakFusion Test Reactor

This paper presents studies of the H+ minority ions driven by Ion Cyclotron Radio Frequency (ICRF) heating in the Tokamak Fusion Test Reactor (TFTR) [ R.J. Hawryluk et al., Phys. Plasmas 5, 1577 (1998)] deuterium plasmas using primarily passive H degrees flux detection in the energy range of 0.2-1.0 MeV. The measured passive H+ energy spectra are compared with active (Li pe llet charge exchange) results. It is shown that in the passive mode the mai n donors for the neutralization of H+ ions in this energy range are C5+ ion s. The measured effective H+ tail temperatures range from 0.15 MeV at an IC RF power of 2 MW to 0.35 MeV at 6 MW. Radial redistribution of ICRF-driven H+ ions was detected when giant sawtooth crashes occurred during the ICRF h eating. The redistribution affected ions with energy below 0.7-0.8 MeV. The sawtooth crashes displaces H+ ions outward along the plasma major radius i nto the stochastic ripple diffusion domain where those ions are lost in sim ilar to 10 msec. These observations are consistent with the model of the re distribution of energetic particles developed previously to explain the res ults of deuterium-tritium (DT) alpha-particle redistribution due to sawtoot h oscillations observed in TFTR. The experimental data are also consistent with numerical simulations of H+ stochastic ripple diffusion losses. (C) 19 99 American Institute of Physics.