Lower-hybrid instability in current-carrying plasmas

The stability of lower-hybrid waves in a collisional, fully ionized plasma carrying a field-aligned current is investigated. From the two-fluid equations in the cold-plasma approximation, a generalized dispersion relation and formulae for the real frequency ω_I and growth rate ω_R are derived. The results of a numerical study are presented showing the dependence of ω_R and ω_I on the angle between the direction of propagation and the magnetic field, the ratio of the electron drift velocity to the parallel phase velocity, and other plasma parameters. Lower-hybrid instability with electron drift velocity small compared with the parallel phase velocity is predicted.