Experiments have been performed on the JET tokamak with 2nd harmonic
ion cyclotron resonance heating (ICRH) of hydrogen in deuterium plasmas
to assess the role of finite Larmor radius (FLR) effects on the resonant ion
distribution function. More specifically, the clamping of high-energy resonant
particle distribution due to weak wave-particle interaction at high energy is
studied. The distributions of ICRH heated hydrogen ions have been measured
with a high-energy neutral particle analyser in the range of 0.29–1.1MeV. By
changing the electron density the energy E*, around which the wave-particle
interaction becomes weak, is varied. The dependence of the ion distribution on
E* is experimentally observed for a number of discharges and FLR effects are
clearly seen to affect the high energy tail shape. Experiments have been analysed
with the combination of ICRH modelling codes PION and FIDO, including FLR
effects, and good agreement with measurements have been found. |