Comparisons of particle tracking and charge deposition schemes for a finite element gun code

A new finite element gun code is under development. In an effort to improve the gun code model, a concept has been proposed recently that treats fields in a typical way, but includes a unique, formal approach to both particle tracking and source allocation. Being a new approach, there are concerns about the speed, accuracy, and appropriateness of this proposal for the electrostatic, steady-state particle-in-cell (PIC) gun model. In order to resolve some of these issues, a variety of particle tracking and charge deposition schemes are being evaluated with respect to accuracy, speed, robustness, and effect on the model. This includes various methods for computing the electric field at the particle locations. For this study, we are using the SAIC 3D gun code AVGUN as a testbed to incorporate and evaluate these methods. Results of a theoretical analysis of the methods will be presented, and a comparison will be made with the empirical results.