Critical current dependence on geometry in the self-magnetic-pinch radiographic diode

The self-magnetic-pinch (SMP) diode is an intense x-ray source for pulsed power driven radiographic systems. This electron beam diode is a critical current limited device often described using equations derived from analytic approximations to large aspect ratio (cathode diameter to anode-cathode gap) variant diodes. A factor, α, is usually used to account for changes in space charge limited electron emission due to the presence of positive ions in the emission region and for the details of the geometry of the diode. The critical current dependence on geometry in the SMP diode has been investigated using the Large-Scale-Plasma (LSP) Particle-in-Cell (PiC) code and results are presented.