ABSTRACT
The beam dynamics of high-current linear accelerators is dominated by the effect of wake potentials of the highly conducting metallic structures surrounding the beam trajectory. In most cases the finite difference methods can be applied successfully for calculation of wake fields in accelerators [ IJ. [2]. However the existing computer codes experience severe problems in short range wake field calculation for ultra short bunches !3J. Two main sources of the problems are the grid dispersion and the staircase geometry approximation.
