Ordinary-mode electromagnetic instabifity for counter-streaming ions with anisotropic temperatures

Abstract

The instability of the ordinary electromagnetic mode propagating perpendicular to an external magnetic field is investigated for two ion beams with anisotropic temperatures, counter-streaming along the magnetic field. A necessary and sufficient condition for instability is derived. The growth rate is calculated, and found to be typically several times the ion cyclotron frequency Ω_i, although in extreme cases γ_max may be as large as (M_i/m_e)½Ω_i.