US2328989A - Gaseous electric discharge device - Google Patents

Description

P 1943- w. H. MARTIN V ,32

GASEOUS ELECTRIC DISCHARGE DEVICE Filed Oct. 4, 1941 INVENTOR y W. H. MA R T/N momflwul AT TORNEY Patented Sept. 7, 1943 *1 Claim. Grammy I This invention relates to gaseous electric discharge devices and more particularly to cathode glow discharge devices. a

An object of the invention is to facilitate the discharge in electricdischarg devices employing a cold cathode.

Another objectof the invention isto facilitate the control of the discharge between electrodes in electric gas discharge devices employing a cold cathode.

In accordance with one feature of the invendevice. i U In accordance with another feature of the invention a grid is provided to control the escape of thermionically emitted electrons from the filament to the space around the anode.

The invention will be understood from the folthe 'centento allow= space for' the anode B to pass 7 the'rebetween. 1

The anode 8 is in the form of a linear red. one end of which is embedded in the press andconnected to a suitable lead wire. The rodanode is surrounded at all portions except at its upper end 'by an insulating sleeve I! which may be of glass.

The auxiliary cathode or filament l may be of thoria free. tungsten and is sealed in the side wall of the vessel I preferably between theanode 1 tion an auxiliary thermionic emitting cathode or p H filament is employed to initiate the discharge bes l tween the main electrodes of thejglow discharge lowing description when read in connection with the accompanying drawing, in which:

Fig. Us a perspective view of one embodiment of the invention with a portion of the device broken away to show the internal structure;

Fig. 2 is a modification of the arrangement shown in Fig. 1; s

Fig. 3 isa schematic diagram of the device of Fig. 1 together with a schematic diagram of an operating circuit therefor;and a Fig. 4 is a schematic diagram of the device of Fig. 2 together with a schematic diagram of a circuit arrangement therefor.

Referring now to the drawing, the device shown in Fig. 1 comprises an enclosing vessel 1, two semi-circular electrodes 5 and 6 constituting a cathode, an anode 8 and an auxiliary cathode H1. The upper surface of the cathode 5, 6 is coated with a suitable electron emissive material, such as strontium and barium oxides. The cathode is of relatively large area compared to the anode 8. The vessel I has a filling of gas, for example, pure argon at a pressure of 1.5 centimeters. A mixture of neon and 1 per cent of argon at a pressure of between 1 to 3 centimeters may be used. Other suitable gases may also be used. Th semi-circular electrodes 5and 6, constituting the cathode, are supported from the press I by members 3 and 4, respectively. The members 5v and 6 may be connected together, preferably within the vessel, by a connection, such as the wire 40.

Either of the support members 3 and 4 may serve as a lead wire for the cathode. The straight edges of said electrodes 5 and '6 are spaced apart in parallel relation and are slightly grooved at Bandthe cathode 5,6. In Fig. 2 a modified form of the device of Fig. 1 isv illustrated, a grid 25 being provided to control the escape of thermionically emittedelectrons from the filament 10 to the space around the anode. The grid is shown in the form of a metallic cup with a central aperture, but it may be of mesh material. It is supported in the side wall of the vessel around the filament ID by a lead wire 26 embedded in the side wall of the vessel.

The operation of the devices of Figs. 1 and 2 will be discussed in connection with the circuit arrangements of the devices shown in Figs. 3 and 4. 7

Figs. 3 and 4 show schematic circuit arrangements for the devices of Figs. 1 and 2, respectively, with a source of current Eb connected to the cathode and the anode. The anode to cathode spacing is such that no breakdown will occur where a voltage Ep is applied between the anode and the cathode. 7

Referring now to Fig. 3, by momentarily closing the key 20, current from the battery Er will rent to a value too' small to cause appreciable self-heating of the filament, while the filament electron emission is too small to supply the cur rent flowing between the main electrodes 5, 6 and 8. Hence, a. glow discharge with a high cathode fall is set up between the anode 8 and the filament l0,. which discharge momentarily transfers to the activatedcathode 5, 6. As diagrammatically indicated in Fig. 3, the filament is operated several volts positive with respect to the cathode to encourage this transfer. A resistance 3| may be used in the anode circuit to limit the voltage applied to the anode. After the main discharge has been initiated it can be stopped by.

opening the key 30, or in any other well-known manner.

Referring now to Fig. 4, by momentarily operating the key 23, current from battery E1 will be connected across the filament l0 through the resistance 2!. This-will likewise cause the fila- 'ment to heat to thermionic emission, so that electrons between the cold cathode and the anode will be acceleratedand willionize the filament toe-node space. The grid 25 serves to control the escape of thermionically emitted electrons from the filament, Ill to the space around lines.

isdesired, for example, in subscribers telephone They may be used, however, as rectifiers or regulators.

Although specific embodiments of this invention have been shown and described, it will be understood, of course, that various modifications may be made therein without departing from the scope andspirit of the invention as defined in the appended claim.

What is claimed is:

A gaseous electric discharge device comprising a cathode having an electron emissive coating,

the anode. The grid 25 is prevented from operat-j ing as a cathode by a high resistance 35, The variable resistance 35 in the. grid circuit isfor the purpose of regulating the voltagefilc applied.

to the grid.

It is apparent that this form 01' device'permits the starting of the discharge by the low voltage,

high current control member l9. The devices of Figs. 1 and 2 are particularly suitable for use Where a current operatedrelay anla-n'ode in cooperative relationship with said cathode, an auxiliary filamentary cathode intermediate said cathode and anode for initiating the dischargebetween said cathode and anode, and an electrode surrounding said auxiliary cathode for controlling the escape of electrons from the auxiliary filament to the space around the anode.

WILLIAM iH.: MARTIN.

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