JOHN VALUN
Broker in Beverly Farms, MA
License number
Massachusetts 74824
Issued Date
Oct 1, 1972
Expiration Date
Jul 9, 1981
Type
Broker
Address
Address
Beverly Farms, MA 01915
Professional information
Miniature Electron Gun With Focusing Grid Structure
US Patent:
4661741, Apr 28, 1987
Filed:
Jun 28, 1985
Appl. No.:
6/749787
Inventors:
John Valun - Beverly MA
Kenneth J. Harte - Carlisle MA
Kenneth J. Harte - Carlisle MA
Assignee:
Control Data Corporation - Minneapolis MN
International Classification:
H01J 2948, H01J 1946
US Classification:
313447
Abstract:
An electron gun includes a preferably non-metallic apertured grid with a flat upstream-facing surface closely spaced from and parallel to a flat emitting surface of a cathode. The grid aperture diverges in a downstream direction and has its peripheral wall contoured to shape the transverse cross-section of an emitted electron beam at a predetermined downstream location, preferably at the beam crossover. The peripheral wall of the grid aperture is devoid of sharp transitions, has a circular cross section to produce a circular beam crossover of minimum diameter, and has a convex segment extending from the upstream end of the aperture and joining a concave segment extending to the downstream end of the aperture. The convex first segment has a smaller radius of curvature than the second concave segment and has its center of curvature disposed substantially at the upstream facing surface. In the preferred embodiment the grid is made of a synthetic sapphire and the cathode is a thermionic cathode made of lanthanum hexaboride.