Numerical simulation techniques for the study of high-power diodes for radiography

Summary form only given. In the IPROP and LSP codes, we have developed the capability for multi-dimensional simulation of dense plasmas in pulsed-power devices. The plasma modeling includes an implicit electromagnetic field solver that permits large time steps and fine resolution of plasma in one direction and coarse resolution in the other directions. The new solver is well suited to the simulations of thin surface and dense bulk plasmas. These codes use a hybrid (fluid/kinetic) description of the plasma electrons and kinetic modeling of ions. This description permits the simulation of a high-density plasma without micro time steps and zoning. In order to determine the rate at which contaminants leave the surface, we also model the electron interaction with the anode. The interaction is presently modeled utilizing Moliere multiple scattering and an energy-loss model for treating the interaction of high-energy electrons with the anode. A new model utilizing the ITS series of Monte Carlo algorithms is being implemented to more accurately simulate energy loss, scattering and production of secondary electrons. A detailed description of these models and some relevant examples will be discussed.