Abstract
Numerical simulation including the space charge effect was carried out to determine the basic parameters for a newly designed 100 kW (40 kV, 2.5 A) Pierce-type electron gun. It is required that the electron beam of 2.5 A could pass through the aperture hole without colliding with the electrode and lens assembly. Three models of electrode assembly, were examined, A) with a cone-shaped Wehnelt B) with a spherical Wehnelt, and C) same as B except a larger anode hole. The space charge limited current exceeds 2.5 A for model B and C. However, electron beams in model B collide with the anode inlet irrespective of the operating conditions. The model C was found to satisfy the requirement under an adequate operating condition of electromagnetic lens.
