Accurate calculations of thermionic electron gun properties

Thermionic triode electron guns with directly heated hairpin tungsten cathode are still in wide use in many microscopes for their low requirements on operation conditions, high emitted currents and low service costs. In ISI Brno we started with simulations of thermionic electron guns for electron beam welding machine [1] used also for experiments with electron beam micromachining. Numerical simulations enable us to understand space charge effects and it can help us to improve the geometry of gun electrodes.