GB723987A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

723,987. Discharge apparatus. ELECTRIC & MUSICAL INDUSTRIES, Ltd. Dec. 23, 1952 [Dec. 28, 1951], No 30262/51. Class 39 (1). An electron discharge device including an electron gun is provided with a member composed of or coated with a material capable of absorbing gases in its solid state, such as thorium, zirconium, titanium, halnium, vanadium, niolium or tantalum; the member is so arranged that in operation it is heated preferably by the cathode or the cathode heater, so that a temperature gradient is set up along its length. An indirectly heated cathode 1, Fig. 1, may be surrounded by a cathode screen electrode 4 which may be of nickel coated on one or both surfaces with getter material; with the cathode at 800‹C. the area of the electrode 4 indicated at 5 will attain a temperature range of 200‹-600‹C., a suitable range for a thorium getter. If zirconium is used as the getter a higher temperature is necessary, and a range of 400‹-800‹C. may be obtained by surrounding the electrode 4 with a heat shield, Fig. 2 (not shown). In another arrangement, Fig. 3, for use with cathodes of a diameter less than 5 mm. a heater 7 may be arranged between the cathode 2 and the cathode screen 4, which is surrounded by a heat shield 6. Flanges 9, 8 may be provided on the cathode and screen electrode respectively to prevent loss of heat. With large cathodes a similar arrangement may be used, the cathode being provided with an additional internal heater, one of the two heaters being switched off when the cathode reaches its working temperature. In a further modification, Fig. 5, a rod 10 of thorium or zirconium is attached to the centre of the cathode to getter positive ions; for a cathode -10 mm. in diameter the rod may have a diameter of 0.5 mm. and a length of 2 mm., its temperature varying from 800‹C. at the cathode end to 400‹C. at the free end. The constructions shown are suitable for use in klystrons.