Excitation of lower-hybrid instability by longitudinal currents

The stability of a homogeneous plasma with currents along the magnetic field is investigated. It is found that electrons streaming along the magnetic field lines in a neutralizing positive ion background could excite lower-hybrid instability. The critical drift velocity should exceed the parallel phase velocity for instability: Vd>ωr/k∥, where ωr is the lower-hybrid frequency (ΩeΩi)1/2. This condition is found to be easily met in the laboratory and space plasmas and is applicable both in the collisionless and collisional palsmas.