Adaptive Space-charge Meshing in the General Particle Tracer Code

Efficient and accurate space-charge calculations are essential for the design of high-brightness charged particle sources. Space-charge calculations in the General Particle Tracer (GPT) code make use of an efficient multigrid Poisson solver developed for non-equidistant meshes at Rostock University. GPT uses aggressive mesh-adaptation with highly non-equidistant spacing to speed up calculation time, where the mesh line positions are based upon the projected charge density. Here we present a new meshing scheme where the solution of an intermediate step in the multigrid algorithm is used to define optimal mesh line positions. An analytical test case and comparison with a molecular dynamics calculation of an ultrafast electron diffraction experiment demonstrate the capabilities of this new algorithm in the GPT code.