Application of the delta-f method to ICRF heating

Inclusion of ion kinetic effects (which resolve resonances and determine ion absorption) into the computation of plasma response to ICRF wave fields has often involved simplifications, such as small-but-finite Larmor radius expansions and neglect of drift excursions (finite banana width). The accuracy of such approximations is not always clear. Time-domain particle-based techniques don't suffer such restrictions, but do suffer from sampling noise. The utility of an optimized (for noise reduction) delta-f particle-based computation of self-consistent plasma currents is examined for a prototypical mode-conversion problem--electromagnetic to plasma wave conversion at the critical layer (where the em wave frequency equals the plasma frequency). A prescription for incorporation of the method into full-wave ICRF propagation solvers is discussed.