GB650935A - Improvement in electron discharge device - Google Patents

Abstract

650,935. Magnetrons. SYLVANIA ELECTRIC PRODUCTS, Inc. Sept. 23, 1946, No. 28467. Convention date, Sept. 29, 1945. [Class 39 (i)] [Also in Group XL (b)] A magnetron comprises two interdigitated anode members 10, 11, Fig. 1, surrounding a cathode 6, a cavity resonator connected across the anode members, preferably via discs 4, 5 sealed through the envelope, and the device is of fixed or adjustable asymmetric construction to enable the establishment of a mode of oscillation within the cavity in which a stationary electric field varies through one or more maxima and minima in accordance with the angular position at a constant radius around the axis of the anode, the asymmetry being other than that due to an output coupling loop. To provide the asymmetry, (a) the cathode may be positioned eccentrically within the anode, Fig. 9 (not shown); (b) one anode finger may be longer or thinner than the others, Figs. 10, 11 (not shown), or two diametrically opposite fingers are larger than the others; or (c) the asymmetry may be in the external cavity resonator, e.g. by removing one or both tuning screws 43, Fig. 13, on the cavity diameter perpendicular to the radius passing through the output coupling loop. The cathode 6 is indirectly heated having a heater 7 supported between ceramic members 8, 9, and the cathode leads 14, 15 may be of a chromium-nickeliron alloy suitable for sealing to glass. Flanges 24, 25 confine the discharge. The anode members 10, 11 are connected to discs 4, 5 via flanges 10a on the former and flanges 12 and fingers 13 on the latter, the parts being soldered together. The magnetic field is produced by a permanent or electro-magnet 37. Five, seven, or nine tuning screws 43, Fig. 13, may be used and may have blocks at their inner ends to contact the upper and lower ends of the resonator conductively or insulatingly. The mode of oscillation is discussed in detail and is distinguished from the known # mode and other radial modes. In the discussion of the known # mode it is stated that the device may operate at a harmonic of its resonant freequency in which case the glass envelope parts are at voltage nodes. Specifications 449,920, 465,650 and 550,081 are referred to.