Abstract: A broad-beam high energy electron accelerator has an electron injection section arranged for increased current density with greater uniformity and higher transmission through the foil exit window. A plurality of cathode rods are disposed in a transverse plane and spaced at about 2.4 cm, and a reflector plate behind the cathode rods is biased negative relative thereto. A planar control grid is disposed distal of said cathode rods and a screen grid is disposed parallel to and distal of the control grid. Field-shaping wires are disposed in a plane parallel to the plane of the cathode rods and between the same and the reflector plate, with the respective field-shaping wires being disposed parallel to said rods and midway between them. The same positive bias (e.g., 11 kV) is applied to both the control grid and the field-shaping wires.