Electromagnetic Ion-Beam Instabilities in the Solar Wind

Abstract
The stability of a plasma consisting of two, unequal, isotropic, ion beams streaming along a uniform magnetic field has been investigated by numerically solving the full electromagnetic, Vlasov, linear dispersion relation for high-β plasmas. Three instabilities are found: One is closely associated with the usual Alfvén mode and the two others with the "fast" or magnetosonic mode. The importance of these instabilities for certain neutral-beam-injection experiments and in the solar wind is emphasized.