Abstract: A high-performance, unipotential-type electron gun is disclosed. The gun according to the invention comprises a series of apertured electrodes having electrical potentials thereon for establishing electrostatic fields therebetween. The electrodes, which are aligned in spaced relation on an axis, are in the order named, lower end means including a cathode for generating a source of electrons from which an electron beam is formed, apertured plate control and grid electrodes for forming, in conjunction with a cathode and the control electrode, a first cross-over constriction in the beam. The beam exhibits upon divergence from the cross-over constriction a relatively steep cross-over emergence angle. The gun includes a three-element focus lens means for producing a finely focused electron beam.