Steady-state ion beam modeling with MICHELLE

Summary form only given. A new steady-state ion beam model for application to ion thrusters has been implemented in the MICHELLE code. MICHELLE is a new finite-element (FE) two-dimensional (2D) and three-dimensional (3D) electrostatic particle-in-cell (PIC) code that has been in use for the past several years and was designed to address the recent beam optics modeling and simulation requirements for vacuum electron devices, ion sources, and charged-particle transport. MICHELLE has both a steady-state and time-domain model. The steady-state model is perfectly suited to relatively rapid modeling of the ion thruster application, since there is an equilibrium flow condition that needs to be understood. The steady-state model is often much faster than a time domain model, when an equilibrium solution is the desired result. The code also supports both structured and unstructured meshes. The need for efficient modeling of ion beams comes about from, in addition to ion thrusters, other applications such as ion implantation and chemical vapor deposition. Common to these applications is the need for three-dimensional (3D) simulation of volumetric ion sources, ion acceleration, and optics, with the need to resolve fine structure details in some cases. For ion thruster applications, there is a need to simulate charge exchange between the ion beam and the background neutral gas. What differs from a typical electron gun code is that the new model must support ions and neutrals, the volumetric plasma source, and a charge exchange model.