A volume preserving, improved integrator for charged particles in electromagnetic fields

Abstract:  Accelerator modeling has long relied on symplectic integration for tracking particles. However, in cases with strong space charge, symplectic maps are not available. Recent work indicates that symplecticity is not needed, that simple volume preservation is sufficient. To this end, we have developed a volume preserving particle push that is shown to have excellent phase-space preservation properties, which we expect to be advantageous for self-consistent (significant space-charge) beams. As a second part of this talk, we will discuss recent developments in collisional interactions within the VSim framework, which may have use for FRIB, including for beam-gas interactions. The new framework has been designed to be GPU ready, and it has been validated for collisional dynamics.