Physical Effects of Aleph's Semi-Implicit Particle-in-Cell Scheme

System-scale kinetic simulation of high-density plasmas in vacuum arc discharges is challenging due to stability constraints placed on the timestep and mesh size in conventional particle-in-cell (PIC) methods. In recent years, an energy-conserving semi-implicit PIC
^1,2
(SIPIC) scheme has been implemented in the low-temperature plasma simulation code Aleph
³
that allows the circumvention of the finite-grid instability and relaxes the timestep requirement that the electron plasma frequency be resolved. However, how/if the semi-implicit scheme affects the underlying physics of the discharge is not well understood. In this work, the influence of SIPIC on particular quantities of interest in vacuum-arc discharges is investigated and comparisons between analytical theory and explicit electrostatic PIC are made where possible.