Simulation of an aberration-compensated parallel beam shift for fast electron-beam welding

A parallel beam shift system and a magnetic objective lens with a dynamic focus coil for fast electron-beam welding and drilling will be presented. Three different beam shift systems for cathode-protection were discussed and numerically simulated, using the program GIOS and the 3D-software package of MEBS. The best results were achieved for a pre-lens beam displacement system, capable of a displacement of 20 mm and a short working distance, and whose second-order aperture aberrations are partially compensated and below the spherical aberration of the objective lens.