US2020727A

US2020727A - Gaseous electric discharge device

Info

Publication number: US2020727A
Application number: US597376A
Authority: US
Inventors: Gaidies Georg; Reger Martin
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1931-03-14
Filing date: 1932-03-07
Publication date: 1935-11-12
Anticipated expiration: 1952-11-12

Description

Nov. 12, 1935. s. GAIDIES ETAL 2,020,727

GASEOUS ELECTRIC DISCHARGE DEVICE I Filed March '7, 1932 INVENTORS MW WW ATTORNEY Patented Nov. 12, 1935 UNITE STATES PATENT OFFICE 2,020,727 GASEOUS ELECTRIC DISCHARGE DEVICE Application March '1, 1932, Serial No. 597,376 In Germany March 14, 1931 4; Claims. (01. 176-126) The present invention relates to gaseous electric discharge devices generally and more particularly the invention relates to electrode structures for such devices.

It has long been a practice in the art to use cold, sheet-metal electrodes in electric discharge devices, particularly those used for illumination, which have a gaseous atmosphere comprising gases, or vapors or a gas-vapor mixture. Such electrodes are not capable of passing large currents for long operating periods without disintegrating, such disintegration shortens the useful life and lowers the efficiency of said electrodes. As the rate of disintegration increases 5 with the strength of the current it has been necessary, heretofore, to use electrodes of large area even with a comparatively weak current, such as 100 milliamperes, to avoid a rapid disintegration of the electrode. material.

3 The object of the present invention is to reduce the rate of disintegration of cold, sheet-metal electrodes useful in electric discharge devices. A further object of the invention is to provide a cold, sheet-metal electrode which is more efli- 5 cient and which is capable of passing greater currents for longer periods of operation than those now known in the art. Still further objects and advantages attaching to the invention and to its use and operation will be apparent to those skilled in the art from the following particular description.

The main cause of disintegration of this type of electrode is the large cathode drop. This cathode drop may be greatly reduced by providl ing in the container of an electric discharge device an electron emitting material, such as an alkali or an alkali earth, which activates the operating surfaces of the electrode to substantial y reduce the cathode drop and therewith the rate ill of disintegration of the sheet metal electrode. The presence of this activating material in the container of a gaseous electric discharge device is beneficial to the gaseous atmosphere since itacts as a getter, uniting with any impurities 45 therein. According to this invention the new and novel cold, sheet-metal electrode for electric discharge devices is provided with a chamber having a recessed, contracted opening, or a plurality of recessed, contracted openings in the di- 50 rection of the discharge path, and the activating, electron-emitting material is placed in said chamber. A steady and permanent supply of activating material in an electrode having such a structure is assured since the sputtering and 55 dissipation of the electron-emitting material is controlled and reduced to a minimum. Having this structure the electrode is more eflicient than previous cold, sheet-metal electrodes of the same size, has a longer useful operating life and is capable of passing greater currents for longer 5 operating periods.

In the drawing accompanying and forming part of this specification three embodiments of the new and novel electrode are shown, in which Fig. l is a side elevational view of an electric l0 discharge device the container thereof being broken away in the region of the electrode, an embodiment of the new and novel electrode bein shown in cross section,

Fig. 2 is a sectional view oi another embodil5 ment of the invention and Fig. 3 is a similar view of still another embodiment of the new and novel electrode.

Like numbers denote like parts in all the figures.

Referring to Fig. 1 of the drawing l is the container of an electric discharge device filled with gases, or vapors, or a gas-vapor mixture such as neon, nitrogen, mercury, or a mixture of argon and mercury. The new and novel cold, sheetmetal electrode is sealed and supported therein by lead 6. Said electrode comprises a chamber 2, having an open-ended, cone shaped part 5 recessed therein. The inner wall of said chamber 2 is coated with an electron emitting material such as caseium, sodium, potassium, barium, etc. or, when desired, the activated oxides of these materials. The inner wall of said chamber 2 supports the electric discharge in said electric discharge device when the device is first placed into operation, and due to the sputtering of the coating oi the electron-emitting material on the inner walls 01 said chamber 2 a small portion of the particles of said sputtered material passes through the opening 4 in said part 5 and deposits onthe outer wall of said part 5 so that said outer wall is activated and also supports the electric discharge. Thus even the small, minute portion of the sputtered particles of electron-emitting material that pass through the opening 4 are used on the outer wall of said part 5 and aid in the current conduction process. Having this structure the electrode has a long operaclng life since the sputtering and dissipation of the activating material is controlled by the recessed, contracted opening 4.

In the embodiment shown in Fig. 2 the open, cone shaped part 5 protrudes from the chamber 2, the end of greater diameter being in the direction of the discharge path. The inner wall of said part 5 as well as the inner wall of said chamber 2 is coated with electron-emitting material similar to that disclosed in the discussion of Fig. 1. Having this structure said part 5 facilitates the starting of the electric discharge in an electric discharge device in which it is used. Openings ment of the invention than with that shown in Fig. 1 since a greater activated discharge supporting surface is available.

In the embodiment of the electrode shown in Fig. 3 a number of circular recesses 8 are provided in said chamber 2 in the direction of the discharge path. Each of said recesses 8 has a slit 9 at the bottom thereof, and each of said recesses 8 is a. discharge supporting surface. A small portion of the sputtered particles from the coating 3 of electron-emitting material in said chamber 2 pass through said slits 9 and stick to the surface of recessed parts 8 to maintain these discharge supporting surfaces in an activated condition; Stronger currents may be used in connection with this embodiment of the invention than in that shown in Fig. 2 since a greater area of activated, discharge supporting surface is available.

In the above described electrode structure the sputtering and dissipation. of the electronemitting, activating material is controlled by the recessed openings in said electrodes so that said material lasts a long time and the discharge supporting surfaces of the electrodes are maintained in an advantageous condition to the end that greater operating currents may be used on a device equipped with cold, sheet-metal electrodes than was practical hitherto.

While we have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its use and operation may be made by those skilled in the art without departing from the broad spirit and scope of the invention.

What we claim as new and desire to secure 1 by Letters Patent of the Unitedstates is:-

1. An electric discharge device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being a hollow electrode having a truncated conical 1c part protruding therefrom and opening into the interior thereof, the end of greater diameter being in the direction of the discharge path, the inner walls of said conical part and of said electrode being coated with electron-emitting material.

2. An electric discharge device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being a hollow electrode having a plurality of circular recesses of decreasing diameter opening into the interior thereof, the part of greater diameter of said recesses being in the direction of the discharge path, the inner walls of said electrode being coated with an electron-emitting material.

3. An electric discharge device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being a hollow electrode having a contracted, tapering portion opening into the interior thereof, the larger end of said contracted, tapering portion being in the direction of. the discharge path, the smaller end of said tapering portion being appreciably smaller in diameter thanthe part of said electrode into which said tapering portion opens, the inner walls of said electrode being coated with electron emitting material.

4. An electric discharge device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being an elongated, hollow electrode, the wall thereof facing the discharge path being a re-entrant truncated cone opening into the interior of said electrode, the end of greater diameter of said cone being in the direction of the discharge path, and a coating of electron emitting material on the inner walls of said electrode.

GEORG GAIDIES. MARTIN REGER.