Patent ID: 6094010
Filing Date: 2000-07-25
Classification: H01J

Abstract:
An electron gun comprising:a conductive chamber defining a cavity;a photocathode for emitting photoelectrons into the cavity when light is applied to said photocathode;a wave guide coupled to the cavity for guiding a micro wave into the cavity;an opening disposed in a wall of said conductive chamber for guiding the photoelectrons emitted into the cavity out from the cavity to form an electron beam; anda flow path through which coolant flows to forcibly cool said conductive chamber;wherein said conductive chamber comprises a tube having an inner circumferential surface of a tubular shape and a protrusion having a through hole defined in a central area thereof, and said protrusion comprises a rim like extension from the inner circumferential surface defined by the tube toward a center axis of said conductive chamber at a position along an axial direction of said conductive chamber;wherein said flow path enters the wall of said conductive chamber from an outer circumferential surface thereof and then returns to the outer circumferential surface, and a partial region of the flow path passes a position which is closer to the center axis of said conductive chamber than the inner circumferential surface of the tube; andwherein said flow path is folded in an inside of the protrusion at a position which is closer to the center axis of said conductive chamber than the inner circumferential surface of the tube, and then returns to the outer circumferential surface of said conductive chamber.