Particle tracking on unstructured grids

Summary form only given, as follows. We report on recent developments and tests of a novel particle tracking algorithm. The novel algorithm is motivated by the finite element gun code MICHELLE and automatic mesh generators which typically provide unstructured grids. Particles are tracked element by element through the unstructured grid, stopping and then restarting at each element boundary crossing. Within each element the particles are tracked in the element´s local coordinate system. Excellent accuracy is achieved with high order integrators despite discontinuities arising from the finite element field solution. Tests on unstructured grids with linear and quadratic elements are shown. Field errors and integration errors are compared.