Three-dimensional effects by beat wave excitation in magnetoactive plasmas

The excitation of plasma waves in magnetoactive plasmas by the beating between two circularly polarized external high-frequency electromagnetic waves is analyzed in the linear fluid theory by taking into account the radial profile of the amplitudes. A low frequency resonance is found which depends, other than on the plasma density and the radial profile, also on the electron cyclotron frequency. This circumstance allows to tune the system with a given plasma dinsity, a fixed beat wave frequency and a given radial profile by adjusting the intensity of the external magnetic field. In such a way the resonance condition can be easily attained. The relevance of this result concerns plasma accelerator physics as well as the generation of coherent radiation by means of plasma wigglers. (Author). 9 refs