Resonant cavity magnetron having built-in magnetic pole shoes with an electrically conductive metal coating to prevent flash-over to the cathode

摘要

1,017,045. Magnetrons; cathode materials. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. Sept. 15, 1964 [Sept. 18, 1963], No. 37635/64. Heading H1D. A resonant-cavity magnetron comprising two coaxial, axially spaced substantially frustoconical pole shoes 4 each having an axial bore to accommodate the ends of a central cathode assembly has the surface of the bore of each pole shoe formed, at least in part, by a coating 10 of a high melting point metal having a thickness of at least three tenths of a millimetre. As shown, the magnetron includes a cathode consisting of a molybdenum body 5, 6 with a central body 7 of porous tungsten impregnated with barium aluminate, end rings 8 and the ends of body 5, 6 being coated by sintering with a zirconium layer 9, and anode vanes 2, copper members 3 forming end-space boundaries and a copper outer wall 1. The high melting point metal 10 resists sputtering in the event of arcing between iron pole shoes 4 and the cathode assembly and may be molybdenum, platinum or tungsten, the coating 10 being formed by the application of a foil by rolling or by the application of a layer by sintering or by Schoop's treatment or (Fig. 2, not shown) each pole shoe may have a metal ring soldered to it.