19.2: Modeling emission processes in the finite-element MICHELLE gun & collector simulation code

The MICHELLE code is a Finite-Element Electrostatic Particle in Cell code for application to 2D and 3D particle beam formation, transport, and collection. Although its initial development focus had been for DC electron guns and depressed collectors, other applications such as RF electron guns, ion thrusters, photocathodes, etc. have become a recent focus. The MICHELLE code´s ability to manage large mesh sizes and large particle counts in complex geometries requiring the resolution of disparate spatial scales in 2D and 3D on desktop computers has allowed it to be applied to devices that could not have been readily modeled in recent years. This presentation gives an overview of recent developments in the area of emission physics models including photoemission, dark current, and thermal beams with applications to time-dependent examples.