A two-dimensional, non-linear Fokker-Planck code coupled to a quasi-linear diffusion term is used to calculate the ratio of RF current excited to power consumed by travelling waves in the plasma. Transport loss of electron energy is simulated according to a model of stochastic-magnetic-field effects. Results are obtained for waves with phase velocity normalized to electron thermal velocity in the range from 0.175 to 4.0. Scaling to a tokamak reactor is considered.