GB472543A - Improvements in or relating to electric discharge devices - Google Patents

Abstract

472,543. Discharge apparatus. UNIVERSAG TECHNISCHE AKT.-GES., and GABOR, D. March 21, 1936, No. 8528. [Class 39 (i)] In apparatus as described in Specification 455,967, having a " dark discharge " in one or more inner spaces 10, Fig. 1, separated from a plasma discharge space 11 by the perforated " plasma-filter " 3 described in Specification 442,307, the hot cathode supplying electrons to the space 10 is replaced by an arc discharge in a cathode space 9 separated from the space 10 by a perforated screen 5. To maintain a " dark discharge " in the space 10, the screen 5 is of fine-mesh metal gauze which is preferably connected by a metal casing 4 to a conductive layer on the side of the filter 3 facing the space 10 to form an equipotential surface about the space 10. The size of the apertures in the parts 3, 5 are related to the pressure of the filling of neon or mercury. The discharge is started by connecting the parts 3 ... 5 at least temporarily to the anode 6 through a high resistance 7, such as a carbon leak. The filter 3 may be of insulated gauze as described in Specification 455,009 or may consist of a metal sheet with conical projections 13, Fig. 2, about its aperture 14 and coated with insulation 15 as shown. The cathode 2 in the space 9 may be directly or indirectly heated or may be a metal pool. Constructions of units including the parts 2 ... 7 are described for use on D.C. and A.C. In one arrangement, Fig. 4, for use on A.C., indirectly heated cathodes 43, 44, Fig. 4, serving alternately as the cathode 2 and anode 6 are arranged close to the gauze 5 and project through a metal plate 41 backed with insulation 42. A partition 37 extends to the filter 3. A metal case 55 surrounds the casing 4 to prevent it from being sputtered and is connected, to act as a starting electrode, to one end of a resistance 51, the other end of which is connected to the casing 4 and the centre of which is connected to the cathode heaters. A grid in the space 10, Fig. 1, may act as ion collector and its potential may be varied to control the current in the device. In one such arrangement, Fig. 9, the cathode is a mercury or alkali pool 69 in a nickel-chromium cup 68 sealed to the glass envelope 67 filled with inert gas and the anode 75 is of nickel-chromium or ferrochrome. The control grid 77 is arranged between the parts 3, 5. The cathode spot is centred by a funnel 70.