GB1236719A - High frequency beam tubes - Google Patents

Abstract

1,236,719. Velocity-modulated tubes; attenuators. VARIAN ASSOCIATES. 22 May, 1970 [16 June, 1969], No. 25004/70. Headings H1D and H1W. In a high-frequency tube-as shown, a klystron-in which a current density modulated beam passes into a collector 13 which is insulated by blocks 21 and ring 22 from the main body of the tube, the escape from the tube of radiation which passes through the gap 27 and insulation ring 22 is prevented by a metal enclosure 26 which contacts the outer electrode of a bypass capacitor 32, and which forms part of an air-filled chamber 35 surrounding the ring 22 and housing wave-absorbing means 36 which is electrically insulative at relatively low frequencies but absorptive at the operating frequency of the tube, whereby arcing across the ring 22 due to resonance modes of oscillation in the chamber is prevented. Means 36 may be constituted by a conduit 37 of loss-free dielectric encircling the collector and containing a lossy coolant liquid-e.g. aqueous sodium dichromate -or the conduit itself may be of lossy material e.g. neoprene rubber. The coolant circulates around a vaporization cooler system which includes a condenser, the conduit 37, and the boiler 18. The collector and cooling structure is secured by screws 31 to a polepiece 8; the capacitor 32 is formed by nylon sheet wrapped around the boiler wall 16 and covered with a brass sheet 33; and the collector is provided with axially directed cooling fins 13.