An arc-discharge-based electron source is described, which is designed for forming a pulsed wideaperture electron beam in the forevacuum pressure range (4-15 Pa). At an accelerating voltage of 12 kV, a current of 80 A was extracted from the emitting surface with an area of 80 cm(2) in the submillisecond range of pulse durations. The current density distribution over the beam cross section is close to a Gaussian function, and the surface-averaged beam energy density in a pulse reached 10 J/cm(2).