Instability of the electromagnetic ordinary mode in counterstreaming plasmas

The instability of a linearly-polarised electromagnetic ordinary mode in a plasma and propagating perpendicular to a uniform magnetic field caused by a counterstreaming of electrons along the latter is studied using a Vlasov plasma model. The results show that (i) for weak magnetic fields, the thermal effects stabilise the ordinary mode; (ii) for strong magnetic fields, the thermal effects destabilise the ordinary mode.