Aspects of Nonlinear Heating by Lower Hybrid Waves

Nonlinear instabilities driven by waves with frequencies comparable to the lower hybrid frequency are examined both analtyically and numerically using particle simulation techniques. Both the oscillating two-stream and ion-cyclotron instabilities are discussed. It is found that ion-cyclotron damping can be a more effective mechanism for driving instabilities in a hot tokamak plasma than electron Landau damping. Despite the one-dimensional nature of the simulation, the simulation results are useful for the interpretation of data obtained in recent lower hybrid heating experiments.