High emittance electron source having high illumination uniformity

摘要

Direct and indirect electron bombardment provide a sufficiently high degree of temperature uniformity across the emitting surface of a large-area electron source for an electron beam projection system such that a broad beam having illumination uniformity within 1% can be achieved. A diode gun is used to obtain extraction field uniformity and maintain uniformity of illumination. Power requirements and power dissipation in beam periphery truncating apertures is reduced by roughening the surface of a monocrystalline cathode or depositing materials having a higher work function thereon.