Instabilities in magnetically insulated gaps with resistive electrode plasmas

Collisional plasma layers exist on the electrode surfaces of magnetically insulated gaps. Coupling of the cathode electron sheath with these plasma layers leads to instabilities. These instabilities are of two types: (i) a destabilized negative energy mode on the electron sheath and (ii) a new low-frequency resistive mode. The growth rates and physical picture of these modes suggest that they might be extremely dangerous in practice, leading to sporadic breakdown of magnetic insulation.