Half‐Cell RF Gun Simulations with the Electromagnetic Particle‐in‐Cell Code VORPAL

We have simulated Brookhaven National Laboratory’s half‐cell superconducting RF gun design for a proposed high‐current ERL using the three‐dimensional, electromagnetic particle‐in‐cell code VORPAL. VORPAL computes the fully self‐consistent electromagnetic fields produced by the electron bunches, meaning that it accurately models space‐charge effects as well as bunch‐to‐bunch beam loading effects and the effects of higher‐order cavity modes, though these are beyond the scope of this paper. We compare results from VORPAL to the well‐established space‐charge code PARMELA, using RF fields produced by SUPERFISH, as a benchmarking exercise in which the two codes should agree well.