Recent advances in the MICHELLE 2D/3D electron gun and collector modeling code

The MICHELLE code is a new Finite-Element (FE) two-dimensional (2D) and three-dimensional (3D) electrostatic particle-in-cell (PIC) code that has been designed to address the recent beam optics modeling and simulation requirements for vacuum electron devices, ion sources, and charged-particle transport. Problem classes specifically targeted include depressed collectors, gridded-guns, multi-beam guns and sheet-beam guns. The focus of the development program is to combine modern finite-element techniques with improved physics models. The code employs a conformal mesh, including both structured and unstructured mesh architectures for meshing flexibility, along with a new method for accurate, efficient particle tracking. New particle emission models for thermionic beam representation are included that support primary emission, and secondary emission is handled with an advanced model. This presentation focuses on two significant advances to MICHELLE over the past year; hybrid structured/unstructured mesh support, and a time-domain electrostatic algorithm.