Optical frequency mixing near the cyclotron frequency for plasma heating

The nonlinear mixing of two laser beams to drive a mode with a frequency near the cyclotron frequency of either the electrons or ions for plasma heating is investigated. The beat frequency wave that is generated is not required to be a natural mode in the plasma. As a result, the heating scheme is considerably less sensitive to fluctuations in the magnetic field, the plasma density, and in the frequencies of the mixing laser beams than in the case where a natural mode in the plasma is generated. The results that are obtained predict a considerable enhancement in the power absorption by the plasma in a region within the volume of interaction of the two laser beams. The extent of the strongly heated region is determined by the transfer of energy from the higher frequency laser to the lower frequency laser as the two beams propagate through the region of interaction.