Towards a self-consistent LSP model of an electron beam diode

The Large Scale Plasma (LSP) simulation tool [1] was used to investigate two different methods of modelling electron beam impact induced anode plasmas in a diode load connected to a high voltage pulsed power machine. This involved emulating an experimental study performed by researchers at the Sandia National Laboratory [2]. Both models were based on prior knowledge of the diode current and so are not fully predictive. Self-consistency, however, was evaluated by comparing results from numerical probes simulating Faraday cups, proton count monitors and a thermocouple array against experimental data. Each model assumed that protons were the predominant ion species affecting diode impedance. Of the two modelling methods that were evaluated, a temperature activated space-charge limited proton emission model proved to be the best performer. Results from a small parameter study showed that an anode surface temperature rise of 600 °C had the best agreement with experiment.