The source requirements for a high-throughput projection electron-beam stepper are radically different than those for more typical focused beam systems. The SCALPEL(R), proof-of-concept stepper requires a uniform, 1 mm(2) parallel beam at the mask plane with a convergence angle of 0.5 mad and a beam current on the order of 10 mu A. These requirements translate to an axial brightness of similar to 1000 A/cm(2) sr which is many orders of magnitude less than a typical direct-write electron-beam system. Another characteristic of a radiation source is emittance, the product of beam size, and angular extent. Unlike axial brightness, this property is not conserved throughout the optical column but is reduced by the presence of apertures. The required emittance of the SCALPEL system is similar to 700 mu m mrad at the mask and wafer plane. For comparison, a typical direct-write system might have an emittance of similar to 1 mu m mad at the wafer plane. In principle, the gun emittance requirement can be met with any combination of source size and angular extent. In practice, limitations imposed by spherical aberration in the illumination lenses mean that designs for projection systems need to maximize the source size. In this article we present data from a designed to meet the requirements of the SCALPEL(R) proof-of-concept system. This gun has been built and tested at 100 kV. The tests were carried out on a test stand that examines the beam far-field intensity distribution by means of a yttrium aluminum garnet (YAG) scintillation crystal. Angular intensity uniformity is measured directly by examining the YAG with a calibrated video camera/ frame grabber/486PC system. Source size is determined by looking at the penumbral beam rise from the gun aperture edge in the same system. Results to date show the gun producing a virtual source size of >50 mu m diameter and a uniform beam of angular extent >12 mrad, which corresponds to an emittance >600 mu m mad. The gun is normally run with temperature-limited emission from the (100) lanthanum hexaboride cathode, and it achieves a beam current stability of a few percent per hour. Beam currents of 1-50 mu A and larger can be set by changing cathode temperature. Because of the low brightness required by the stepper, normal cathode temperature is about 1250 K.