Simulation of Space Charge Effects in Electron Optical System Based on the Calculations of Current Density

We present a numerical method for iterative computation of electron optical systems influenced by space charge with an improved accuracy in the same calculation time. We replace the common algorithm for evaluating the space charge distribution with a new one based on the calculation of the current density distribution from an aberration polynomial. We introduce a re-meshing algorithm which adapts the mesh used for the field calculation by the finite element method in each iteration to the actual space charge distribution to keep it sufficiently fine in all areas with non-zero space charge.