GB671700A - Improvements in and relating to electric discharge devices - Google Patents

Abstract

671,700. Discharge apparatus. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 14, 1949 [Dec. 27, 1948], No. 32113/49. Class 39 (i). A discharge device comprises liquid caesium or rubidium and a cathode supported from a ceramic member which forms part of the metal envelope and is adapted to be maintained at a temperature above that of the liquid metal by radiation from the cathode. The cathode comprises nickel vanes, coated with nickel mesh 10, Fig. 1, and supported on a nickel tube 9 which is sealed to the anode container 1 through collar 12, alumina or magnesium silicate insulator 11, brazed sleeves 14, 15 and header 7. The seal between metal and ceramic may be made in accordance with Specification 656,724, [Group XXXVI]. The cathode tungsten heater 23 is wound on a ceramic sleeve 22 on a rod 16 and is welded at one end to the rod and at the other to a stud 24 in the tube plug 25. The terminal rod 16 is sealed to the tube 9 through a sleeve 20, glass cylinder 19 and cap 17 made of an alloy of iron, nickel and cobalt and strengthened by metal plug 18. The cathode is surrounded by a heat shield 30 perforated for the discharge and lined with metal foil. A perforated ceramic disc supported by the tube 9 may space the lower end of the cathode from the anode. The lower header 2 holds the caesium container 3 which during operation has the lowest temperature of any part. Series-connected cooling- jackets are joined by the cylinder 31, with a welded spiral baffle 32, and members 33, 34 with spiral baffles 35, 36. The jacket formed by member 34 is extended over the insulator 11 by bellows 39, sleeves 38, 41 and insulating sleeve 40. Circulation of the silicone oil is effected by baffles 42, and is supplied through conduit 37 and returned to the radiator 45, and tank 46 by pump 47. Starting may be facilitated by a heater 50 spirally wound on the jacket 31. The caesium receptacle 3 is maintained at a temperature of 150-190‹ C. to produce a pressure of 9.2-54 microns. The cathode temperature for the monatomic caesium layer thereon is preferably 750‹ C.; temperature of the insulator 11 and anode and discharge currents are also specified. In a further form, the anode container comprises nickel-iron cylinders 51, 52, Fig. 3, sealed together through a ceramic member 58, and to an iron header 53 which supports the cathode 54 and carries the caesium receptacle 64. Splashing of the caesium is limited by tube 65. A copper anode 59 carries a contact stud 62 supporting cooling fins 63. The cathode 54 comprises mesh covered vanes in a container 60 open only at the end facing the anode. A housing 70 contains glass wool the density of which varies with the desired rate of cooling of the various tube parts.