One dimensional particle-in-cell simulations of a plasma filled diode with an external circuit

Summary form only given, as follows. The dynamical processes of current conduction and sheath evolution in a one-dimensional planar plasma-filled diode coupled to an external LC driver circuit were studied using a particle-in-cell model. The effect of suppressing or allowing electron emission at the cathode surface was examined; a distinctly different phenomena arose in each of these cases. For the case in which no electron emission is allowed from the cathode surface, all of the familiar results of classical sheath theory are shown to be recovered. However, for the case in which space charge-limited electron emission is allowed from the cathode, a very different result is obtained. The emitted electrons form a beam which couples to the fill plasma via a strong nonlinear beam-plasma instability. The result of this beam-plasma instability is a low-voltage conduction phase characterized by the formation of a large potential maximum near the center of the diode gap with a relatively small net voltage drop and significant trapping of electrons out of the emitted beam. Opening occurs when the emitted electron beam decouples from the background plasma and a well-defined bipolar sheath is formed at the cathode which sweeps the ions out of the diode gap. This process has implications for the theory of plasma opening switches