A Model for the Current-Voltage Chatacteristics of a Dielectric between Spherical Electrodes

Current-voltage characteristics and electric field strength distributions are investigated for a dielectric containing thermally generated, low mobility carriers. Spherical electrode geometry is used (as a reasonable approximattion to the more practical point-plane systems) with carrier emission from the electrode of smaller radius. Under some conditions, the injected charge may reduce the maximum field strength (for a given voltage) by almost an order of magnitude; additionally, the maximum field strength occurs at some distance from the smaller electrode. Fast electrons undergoing collision ionization within the dielectric would then cause maximum energy deposition at some point between the two electrodes rather than immediately adjacent to one electrode.