A new design for a telefocus electron gun is presented. Features include a nearly constant minimum FWHM of 180 &mgr; with beam currents of 1−400 &mgr;A at focal distances from 1/2 to 1 1/2 m. The gun is especially designed to operate under adverse vacuum conditions with background pressures as high as 10−4Torr with accelerating potentials of 10 to 60 keV. In addition tn can be remotely focused and positioned from outside the vacuum chamber in which the gun is used.