US1971940A - Gaseous electric discharge device - Google Patents

Description

Aug. 28, 1934. M. PlRANl GASEOUS ELECTRIC DISCHARGE DEVICE Filed July 7, 1931 INVENTOR WZwweZZy fiuwu BY ATTORNEY Patented Aug. 28, 1934 UNITED STATES GASEOUS ELECTRIC DISCHARGE DEVICE Marcello Pirani, Berlin-Wilmersdorf, Germany, assignor to General Electric Company, a corporation of New York Application July 7, 1931, Serial No. 549,271 In Germany July 26, 1930 7 Claims. (Cl. 176124) The present invention relates to gaseous electric discharge devices generally and more particularly the invention relates to means for starting into operation hot cathode, positive column discharge devices of the arc and. glow discharge type similar to that described in co-pending application Serial Number 377,044, filed July 9, 1929, being the invention of Marcello Pirani and Hans Ewest.

It is well known in the art that auxiliary electrodes placed in the region of the main discharge supporting electrodes facilitate the staring of gaseous electric discharge devices. Hitherto it has been the practice in the art to establish a glow discharge between the auxiliary electrode and its respective main discharge supporting electrode to establish the positive column discharge in such devices. The object of the present invention is to establish quickly and certainly the positive column discharge in gaseous electric discharge devices of the type referred to above.

The invention attains its object through the use of auxiliary electrodes which consist of grouped wires presenting a multiplicity of points and containing or being coated with an electron emitting material. Said auxiliary electrodes are connected in the circuit in such manner that the electric discharge between them and their respective main electrodes is a multiplicity of short intense arc discharges which concentrate on the points of the auxiliary electrodes and on spots of the main electrodes.

The intense arc discharges formed in accordance with this invention between the auxiliary electrode and the main electrode cause a prolific emission of electrons and ions as the are discharges concentrated on the points of the wires of the auxiliary electrodes and on spots of the main electrodes rapidly heat these restricted areas to a high intensity. Because of this heavy emission of ions and electrons the main or positive column discharge path is heavily and quickly ionized and therefore the positive column discharge between the main electrodes is established quickly and certainly.

In the drawing accompanying and forming part of this specification an embodiment of the invention is shown in side elevation, the ends of the tube being in section to show the particular arrangement of the electrodes.

Referring to the drawing the electric discharge device comprises a container 1 having therein any suitable gaseous atmosphere well known in the art. Electrode leads 3 and 3' of the main discharge supporting electrodes 4 and 4 are sealed into the stems of electrode chambers 2 and 2', said electrodes 4 and 4' are maintained at a glowing temperature during the operation of the device by the operating current of said device. Leads 3 and 3' are connected to the terminals 5 and 5 of an alternating current source, or said leads 3 and 3' may be connected to the secondary coil of a transformer if desired. Main electrode 4 is a solid, cylindrical body consisting of a sintered mixture of a difiicultly fusible metal such as tungsten, and an electron emissive material, such as the oxides of alkali metals, or earth alkali metals. Main electrode 4' consists of like materials and is a hollow, closed cylindrical body having an opening 7 in the direction of the positive column discharge path. The auxiliary electrode ,6, comprising a brush of fine metal wires coated with electron emissive material such as that described above, is adjacent the main electrode 4 and is so spaced with relation thereto that a multiplicity of short, intense arc discharges is easily established between said electrodes 4 and 6. The auxiliary electrode 6', comprising a group of fine wires coated with a material similar to that of electrode 6, is placed in the interior of hollow electrode 4' with the spread part thereof in the direction of the opening 7 in the back of said hollow electrode 4'. Said opening 7 permits the ions and electrons emitted by said electrode 6 and the interior of main electrode 4 under the influence of the arc discharges between said electrodes 4 and 6' to diffuse over into the positive column discharge path. Auxiliary electrode 6 is connected to current lead 3' of main electrode 4' by lead 8 having a high resistance 9 therein and similarly auxiliary electrode 6' is connected to lead 3 of main electrode 4 by lead 8' having therein a high resistance 9. A choke coil 10 is connected into lead 3 to serve as a ballast resistance for the electric discharge device as is well known in the art.

When current is first applied to the circuit described heretofore a glow discharge first takes place between the main electrode 4 and the auxiliary electrode 6 and a similar discharge takes place between the main electrode 4' and the auxiliary electrode 6'. As the points of the auxiliary electrodes 6 and 6' and the surface of main electrodes 4 and 4' become heated short, intense arc discharges take place which concentrate on the points of the auxiliary electrodes and on spots of the main electrodes. These restricted areas on the main electrodes and the auxiliary electrodes are thus heated to a high intensity so that they emit a heavy stream of electrons and ions which diffuse over into the positive column discharge path to heavily and quickly ionize said path. When the discharge path is sufliciently ionized the positive column discharge is established as the resistance of the ionized positive column discharge path is then less than that of the resistances 9 and 9'.

While I have shown and described a particular embodiment of my invention it will be understood, of course, that numerous modifications, substitutions, and changes may be made in the form and details of the device without departure from the broad spirit and scope of the invention, for example, the electron emitting electrodes may be of any suitable shape and may be heated by any of the methods well known in the art as by a wrapped around heating filament; the auxiliary electrodes may be supported in other ways in the region of the main electrodes; if the device is to operateon direct current a single auxiliary electrode adjacent the cathode is sufficient.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric discharge device comprising a container, a gaseous atmosphere therein, a plurality of starting and operating electrodes sealed therein, at least two of said electrodes supporting the positive column discharge in said device and at least one of said electrodes being an auxiliary electrode and having a multiplicity of arc supporting points, the electric discharge between said first named electrode and the auxiliary electrode being an arc discharge.

2. An electric discharge device comprising a container, a gaseous atmosphere therein, a plurality of starting and operating electrodes sealed therein, at least one of said electrodes being a main discharge supporting electrode and being electron emitting when heated and at least one of said electrodes being an auxiliary electrode and having a multiplicity of are supporting points parallel to a face of said main electrode, the electric discharge between spots on said first named electrode and the points of the auxiliary electrode being a multiplicity of arc discharges to rapidly increase the temperature of spots on said electron emitting electrode to their operating temperature.

3. The method of starting a gasous electric discharge device having main discharge supporting electrodes which are electron emitting when heated which consists in establishing a multiplicity of arc discharges at at least one of said electron emitting electrodes to cause it to initiate an electric discharge in the gas between the main electrodes.

4. An electric discharge device comprising a container, a gaseous atmosphere therein, a plurality of starting and operating electrodes sealed therein, one of said electrodes being a hollow, main discharge supporting electrode and having an aperture in one wall thereof, another of said electrodes being an auxiliary electrode mounted in said hollow electrode and having a multiplicity of arc supporting points, the electric discharge between said main discharge supporting electrode and said auxiliary electrode being an are discharge.

5. An electric discharge device comprising a container, a gaseous atmosphere therein, a plurality of starting and operating electrodes sealed therein, one of said electrodes being a hollow, main discharge supporting electrode, electron emitting when heated and having an aperture in one wall thereof, another of said electrodes being an auxiliary electrode mounted in said hollow electrode and having a multiplicity of arc supporting points, the electric discharge between said main discharge supporting electrode and said auxiliary electrode being an arc discharge.

6. An electric discharge device comprising a container, a gaseous atmosphere therein, a plurality of starting and operating electrodes sealed therein, one of said electrodes being a main discharge supporting electrode, another of said electrodes being an auxiliary electrode and having a multiplicity of are discharge supporting points, both of said electrodes being electron emitting when heated, the electric discharge between said auxiliary electrode and said main electrode being a multiplicity of arc discharges to rapidly raise spots on said main electrode and the points on said auxiliary electrode to an electron emitting temperature.

7. An electric discharge device comprising a container, a gaseous atmosphere therein, a plurality of electrodes sealed therein, one of said electrodes being a main discharge supporting electrode, another of said electrodes being an auxiliary electrode comprising a multiplicity of discharge supporting points, the discharge between said auxiliary electrode and said main electrode being an auxiliary discharge to facilitate the establishment of the main discharge in said device.

MARCELLO PIRANI.

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