Differences Between Quasi-linear and Exact Ion Cyclotron Resonant Diffusion

These studies investigate the validity of ICRF quasilinear(QL) diffusion theory by comparison of QL coefficients from the AORSA full-wave code [1] with ``exact'' Lorentz equation orbit-based coefficients calculated with the DC code using AORSA full-wave fields, for a C-Mod minority-H ICRF heating scenario. We also compare time-dependent distribution functions and power deposition obtained with the coupled CQL3D Fokker-Planck code [2], using the two RF diffusion sets. The resulting synthetic diagnostic NPA energy spectra are compared with experiment. Initial results indicate that ``exact'' RF coefficient-based NPA spectra give improved agreement with experiment [3]. This work investigates the dominant causes of the QL/``exact'' RF diffusion discrepancy.\\[4pt] [1] E.F. Jaeger et al, Nucl. Fusion 46, (2006) S397-S408.\\[0pt] [2] R.W. Harvey and M.G. McCoy, http://www.compxco.com/cql3d.html.\\[0pt] [3] A. Bader et al, Proc. of 13th RF Power in Plasmas Conference, Newport, RI (2011).