Session RP1 - Poster Session VIII.
POSTER session, Thursday afternoon, October 30
Fran Hill Southeast Exhibit Hall, ACC
MICHELLE, which is a new two-dimensional (2D) and three-dimensional (3D) electrostatic equilibrium particle-in-cell (PIC) code, 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 gridded-guns, multi-beam guns, sheet-beam guns, and depressed collectors. 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. One of the key features of the MICHELLE code is its ability to model fine-scale features in a large volume. This has made it valuable for performing sensitivity studies and generating manufacturing tolerance specifications. The MICHELLE code has been released, and has been employed in the design and verification of electron guns and collector designs over the last several years. Much emphasis has been placed on validating the code against other models and experimental data. An open issue for validation concerns secondary emission. MICHELLE has a new extensive secondary emission model, however data is sparse for many beam energies and materials of interest. The application of MICHELLE to multi-beam guns, gridded guns, and multistage depressed collectors will be presented, along with an update of the MICHELLE development regarding the areas of particle tracking, temperature-limited and space-charge-limited emission, and secondary emission.