Magnetically focused line source electron gun

A magnetically focused line source electron gun for selective heat treatment of surfaces is described. A model calculation consisting of an electric field computation routine and a trajectory tracing procedure was performed. An electron gun, corresponding to the model, was built and tested and its characteristics measured. The gun delivered 10 kw/cm2 on a strip of 80×2 mm, which could be scanned over a range of 100 mm in a direction perpendicular to the long dimension of the strip, so that an area of 80×100 mm could be heat treated in a short time of the order of milliseconds. The magnetic focusing provides for uniform electron energy and beam density throughout the scanned area.