Application of external circuit model to MIG gun LFO study

We apply an external circuit model to our simulations of (MIG) Magnetron Injection Guns to improve fidelity and encompass additional physics relating to the voltage and current delivery systems which, to date, have not been included in out models. These studies are primarily intended to look at (LFO) Low Frequency Oscillations, and so inclusion of the external circuit can represent external geometry with relevant time-scale or resonance behaviors, both for turn-on transient and CW behaviors. We combine these new effects with previous analysis which has looked at particle reflections at the maxB point, thermal emission properties, and also with secondary emission physics.