Numerical studies of current generation by radio‐frequency traveling waves

By injecting radio‐frequency traveling waves into a tokamak, continuous toroidal electron currents may be generated. This process is studied by numerically solving the two‐dimensional Fokker–Planck equation with an added quasi‐linear term. The results are compared with the one‐dimensional analytic treatment of Fisch, which predicted a reduced plasma resistivity when high‐phase‐velocity waves are employed. It is shown that two‐dimensional velocity space effects, while retaining the predicted scaling, further reduce the ratio of power dissipated to current generated by about 40%. These effects enhance the attractiveness of steady‐state tokamak reactors utilizing this method of current generation.