GB1191224A - Construction and cooling arrangement for electrodes in an electron discharge device - Google Patents

Abstract

1,191,224. Thermionic valves. GENERAL ELECTRIC CO. 20 Aug., 1968 [28 Sept., 1967], No. 39770/68. Heading H1D. A high frequency electron discharge device has a planar anode, an opposed circular cathode 2 with grooves 22 formed in the surface, a control electrode 4 comprising a metal ring 20 encircling the cathode, a number of bars 21 supported by ring 20 and extending into the cathode grooves and a number of grid wires 23 extending across ring 20 parallel to the bars 21, and an annular insulator 16 for accurately supporting both the cathode 2 and a second metal ring 12 secured to ring 20, the ring 12 acting as a heat sink and being slidable on the insulator 16. The control electrode 4, which may also have a number of thicker wires 24 extending transversely of grid wires 23 and secured to ring 20, is constructed of high thermal conductivity metal to ensure good heat dissipation from the centre of the grid. Grid ring 12 is spaced from the anode by a ceramic cylinder (11), Fig. 1 (not shown), and two annular metal rings 13, one secured to ring 12 and the other to cylinder 11, and which are secured together at 15 by a vacuum-tight joint, with a thin metal shim 14 separating their free ends, allows relative sliding movement between rings 13, such that grid ring 12 is free to expand along the top surface of insulator 16. The lower surface of insulator 16 is sealed to a resilient ring 18 which is also sealed to ring 12 to complete the vacuum-tight joint. In a modification, Figs. 3-6 (not shown), grid bars 21 and grid rings 20, 12 have a laminated structure with conduits passing therethrough to allow the circulation of a coolant, e.g. air, inert gas or water. A number of tapped holes 25 may be provided in grid ring 12 to facilitate connection to an external circuit, e.g. part of a cavity resonator, which increases the heat sink capacity.