An electron accelerator includes a vacuum chamber having an electron beam exit window. An electron generator is positioned within the vacuum chamber for generating electrons. A housing surrounds the electron generator and has a first series of openings formed in the housing between the electron generator and the exit window for allowing electrons to accelerate from the electron generator out the exit window in an electron beam when a voltage potential is applied between the housing and the exit window. The housing also has a second series and third series of openings formed in the housing on opposite sides of the electron generator for causing electrons to be uniformly distributed across the electron beam by flattening electrical field lines between the electron generator and the exit window.