A study of the interaction of strong electromagnetic waves and anisotropic ion beams with a background plasma.

Abstract

The interaction of an anisotropic (in velocity space) ion beam with an isotropic background hydrogen plasma is theoretically investigated. The length and time scales are such that both the ions and electrons are magnetized. Using linear theory, the electrostatic dispersion relation is derived, and solved fully, using no approximations. It is shown that the anisotropy can significantly enhance the instability growth rates as compared to the isotropic case. The importance of ion magnetization is illustrated. Comparisons are made with unmagnetized plasma results. The modulational instability of an arbitrarily-large-amplitude electron cyclotron wave along the external magnetic field is investigated, taking into account the relativistic electron quiver velocity and the relativistic ponderomotive force. Three types of plasma slow responses, the forced-Raman, quasistatic and forced-quasistatic, are considered and a parameter study of the instability growth rates is carried out.