Collisionless evolution of ion distributions in the presence of ion cyclotron resonance heating

Explicit analytical solutions are given for the collisionless time evolution of the distribution function for ions absorbing RF wave power through ion cyclotron resonance heating in a tokamak. Two different scenarios are considered: (i) conventional ICRH and (ii) combined neutral beam heating and ICRH with the RF wave frequency tuned to the ion cyclotron resonance frequency of the injected ions. Finally, the effect of particle trapping on the time development of the distribution function is also analysed.