On the Stability Features of Stationary States in a Plasma Diode with a Reactive External Circuit

The feasibility of developing an alternating current generator based on a plasma diode is being explored. Under certain conditions, in a collisionless regime, electron instability can arise in such a diode, leading to an abrupt breakdown of the current flowing through the inter-electrode gap. Technically, a generator utilizing this effect can be implemented by connecting the electrodes through an inductive element. To determine the optimal operating conditions of the generator, it is crucial to first investigate the effect of the external circuit with an inductive element on the stability of the diode’s stationary states. This study theoretically examines the problem for both over-neutralized and under-neutralized regimes. Dispersion equations are derived for both cases. It is established that the presence of external inductance shifts the instability threshold, lowering it below the Pierce threshold. In this scenario, oscillatory instability develops instead of aperiodic one. The ranges of inductance values that allow the instability to develop are also determined.