High emittance electron source having high illumination uniformity
AssigneeInternational Business Machines Corporation
InventorsSteven D. Golladay, Rodney A. Kendall, Carl E. Bohnenkamp
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Abstract
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.
Claims17
An electron source having high illumination uniformity including
- a monocrystalline cathode having a planar principal emitting surface,
- an anode substantially parallel to said planar emitting surface having an aperture therein, and
- means for heating said cathode by electron and photon bombardment of a surface of said cathode opposite to said planar principal emitting surface.
A method of limiting electron emission from a selected area of a monocrystalline cathode having a planar principal emitting surface exhibiting a first work function including the step of treating said selected area to increase the work function of said selected area to a second work function greater than said first work function.
Dependencies are inferred from the claim text.