A NEW THEORY OF THE PLASMA-FILLED DIODE

The behavior of a planar plasma-filled diode (PFD) is examined in the limit in which the mass of the plasma ions is allowed to approach infinity. In this limit the plasma ions are immobilized and act as a fixed, spatially uniform background of positive charge. Using a one-dimensional, electrostatic particle-in-cell simulation of a PFD coupled to an external LC circuit, it is shown that the PFD still has a low-voltage conduction phase followed by a high-voltage opening phase in this limiting case. An analytic theory is developed that describes the operation of the diode in the immobile ion case, and this theory is shown to be in good agreement with the simulation results. A simple expression is also derived that gives an upper bound on the current that may be conducted before opening as a function of the density of immobile ions. Finally, it is shown that essentially the same process that determines the behavior of the PFD in the immobile ion limit also controls the operation of the PFD in the case where the ions have finite mass and are free to move under the influence of the diode electric fields.