Applications of the Michelle 2D/3D Electron Gun and Collector Code

Summary form only given. MICHELLE is a new 2D/3D steady-state and time-domain particle-in-cell (PIC) code that employs electrostatic and now magnetostatic finite-element field solvers. Over the past several years the code has been employed successfully by industry to design and analyze a wide variety of devices that include multistage depressed collectors, gridded guns, multibeam guns, annular-beam guns, sheet-beam guns, beam-transport sections, and ion thrusters. Here we present features in MICHELLE that are new since our last report and we highlight some recent applications of MICHELLE. We have added a prototype 3D self magnetic field solver based on the curl-curl finite-element formulation for the magnetic vector potential. The solver employs edge basis functions. Current is accumulated with a new algorithm that takes advantage of the unstructured grid particle tracker employed by MICHELLE. The prototype implementation has worked well to date, and is being applied to moderately relativistic sheet-beam guns while we continue to test and develop the solver. The electrostatic field solver now accommodates dielectric media, and periodic boundary conditions are now functional on all grids, not just structured grids. We have added a global optimization module to the user interface. Both electrical parameters (such as electrode voltages) and geometric parameters can be optimized. We will discuss various approaches to optimizing collectors. The presentation demonstrates this new capability on a generic five-stage depressed collector provided by Boeing EDD. We will also report on our progress on adaptive mesh refinement and implementation of the MICHELLE gun code into the STAR analyst environments