US2073715A

US2073715A - Gaseous electric discharge device

Info

Publication number: US2073715A
Application number: US710419A
Authority: US
Inventors: Harry A Stone; Schaefer Frank
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-02-09
Filing date: 1934-02-09
Publication date: 1937-03-16
Anticipated expiration: 1954-03-16

Description

March 16, 1937- H. A. STONE ET AL 2,

} GASEOUS ELECTRIC DISCHARGE DEVICE Filed Feb. 9, 1934 ope,

ATTORNEYS Patented Mar. 16,. 1937- GASEOUS ELECTRIC nrscnanec onvrcn Harry A. Stone and Frank Schaeler, Detroit, Mich.

Application February 9, 1934, Serial No.'710,4l9

20 Claims. (Cl. 176122) This invention relates to improvements in to the release of gases normally occluded by the gaseous electric discharge devices and more parmetallic electrodes and to the fact that the positicularly to a means for protecting and preservtiveions are not positively prohibited from find-= ing the cathodes thereof. ing the exterior surface of the cathode. Fur- In the process of making gaseous discharge ther, if the voltage between the cathode and lamps it is important to expel all gases normally anode becomes abnormally high, the bombardoccluded in the metallic electrodes and likewise ment of the cathode by the positive ions causes to expel all gases which cling to the tube itself. abnormal heating of the cathode, which, in turn This is done by heating the electrodes to a cherry increases the saturation current. The undue red under an electron bombarding process while heating from these or any other causes wears 10 repeatedly subjecting the tube to the suction of away the cathode and has a very deleterious effect a vacuum pump. The temperatures to which the on the life of the tube. It is, therefore, another cathodes are thus subjected are greater than object of the invention to provide a means for 18 those employed during normal operation in order residence immediately adjacent the cathode for that undue further expulsion of gases by the elecabsorbing the gases expelled by the cathode durtrodes will not later occur. Due to the abnormal ing normal operation to prevent undue heating heating and also due to the fact that the tubes and sputtering with the resultant disintegration are always subjected to this process while lying of the electrode and which will thus force the on a work-bench or table, it is necessary to suppositive ions to find the interior of the cathode 2 port the electrodes in spaced relation from the for electron liberation. This support thus acts tube as otherwise the electrode may contact the as a mechanical shield against the positive ions glass, a sin partial fusion and lat r breakage. to the extent that it largely removes the cause of It is therefore an object of this invention to proexternal cathode bombardment, permitting the vide an improved support for the electrode which a positive ions to find the interior thereof and. it

will effectively support and heat insulate the also acts as a chemical scavenger for extraneous 25 electrode from the glass tube. gases.

It is well understood that it is impossible to Disintegration of the cathode as indicated compl ly e p all gases from a metallic elecabove becomes noticeable to an observer because trade even by bombardment under abnormal of the metallic deposit on the interior of the glass temperatures. Also, while the rare gases may tube. This deposit of pure metal has the capacm be obtained in highly purified condition, they ity to absorb or occlude the rare gas and has been contact glass surfaces and lubricated stop cocks known to absorb such sizable amounts of the gas during introduction and thereby become more or as to prevent further operation of the tube. It 5 less contaminated. The presence of such foreign is therefore a further object to provide a cathode gases alters the desired color, requires greater support having the inherent properties of clean- 3% current and may become suflicient in quantity to ing up foreign gases as described above and to preclude operation. It is therefore another object extend this support forwardly of the cathode by of this invention to provide means in the tube an appreciable amount to preclude a deposition 4 which, as here illustrated, is inherent in the ype of the metal on the interior of the tube for a m of electrode support aforementioned, to clean up long period of time. or scavenge all residual foreign gases in the elec- In such devices where mercury vapor is emtrode and tube. played with a rare gas to produce a blue light it During the operation of a gaseous discharge is sometimes difficult to obtain prompt vaporiza- 5 tube the cathode is given a sufficient potential to tion of the' mercury. It is therefore another obdischarge electrons which break down or lonize ject of this invention to provide a cathode supmolecules of the gases by collision. The electrons port as described above, containing a material, thus freed travel with the original or primary such as sodium or potassium, which will combine electrons toward the anode while a greater quanwith the mercury to form an amalgam thereby tum of the positive ions seek the cathode to libretaining'a supply of mercury adjacent the hot- 5@ I erate additional electrons. The positive ions can, test region in the tube for prompt vaporization i under certain conditions, combine with electrons upon re-activation.

at the surface of the cathode and thus form a In carrying our invention into efiect we emlayer of gas thereon extending to the exterior ploy a silicate compound of the alkali or alkasurface of the cathode. This is due very largely line earth groups, preferably in a finely divided 5a condition, as for instance, glass wool, as a. sup port for the electrode, the wool being adapted to fuse by an amount sufiicient to render a quantity of free alkali, as sodium or potassium or 5 barium or strontium, available for use as a scavanger or "getter of foreign gases and as a means for forming an amalgam where mercury is used.

Other objects and advantages either directly described or implied will become hereinafter more fully apparent as reference is had to the accompanying drawing, wherein our invention is illustrated by way of example and in which- Figure 1 is an elevation of a U-shaped gaseous electric discharge tube, partially broken away to clearly illustrate our invention;

Fig. 2 is an enlarged vertical sectional view of one end of the tube illustrated in Figure 1 with an electrode and our improved support therein, and

2 Fig. 3 is a transverse section taken along the line 3-3 of Figure 2.

More particularly, I indicates a hollow glass tube having an electrode 2 sealed in each end thereof. The tube is adapted to be filled with a rare gas, such as neon, argon and the like either with or without an amount of mercury. Each electrode is composed of an energizing lead wire 3 and a tubular bell-shaped electrode proper 4, usually made of copper. Each electrode is surrounded or wrapped with a finely divided silicate compound 5, preferably glass wool. The wool covers a substantial area of the outer surface of the electrode 4 and extends slightly out-- p wardly thereof as indicated at 6.

Upon heating the electrode by current from the lead wire 3 there is a slight fusion of the glass wool with the electrode, releasing an appreciable amount of alkali or alkaline earth metal so that a quantity of free sodium, potassium, barium or strontium, etc., is available at the electrode for absorption of any occluded gas released by the electrode and also for scavenging any foreign gas within the tube. The wool, by encircling the open end of the electrode also acts as a mechanical screen for forcing the positive ions to the interior of the cathode for further electron liberation.

The slight fusion of the wool does not interfere with the electrode supporting function of the wool. In fact, from this standpoint, there is only a, sumcient amount of fusion to assure that the wool will not lose its proper position.

The wool is so fragile that flakes from it become scattered throughout the tube. Upon attaining suflicient heat to decompose, the alkali or alkaline earth metals in these flakes properly serve as a scavenging or getter for foreign gases all along the length of the tube. In any case, the presence of the flakes is not detrimental in any way. It will thus be seen that the provision of this wool serves several distinct functions: it forms an electrode support, a cathode screen, a foreign gas scavenger, an amalgamator and an eifective mitigator of sputtering.

Our invention may be modified. without departing from our invention, and we therefore desire to be extended protection as defined by the scope of the appended claims.

What we claim is:-

1. In a gaseous electric discharge device, a

sealed tube having electrodes therein, and a supporting means of glass wool for maintaining each of said electrodes in spaced relation with said tube, said supporting means completely encircling the electrode and covering in contacting relation a substantial portion of the length of the active end thereof.

2. In a gaseous electric discharge device, a sealed tube having electrodes therein, and glass wool for maintaining each of said electrodes in spaced relation with said tube, the glass wool completely encircling each electrode and covering a substantial portion of the length thereof and extending an appreciable distance beyond the active end of the electrode.

3.'In a gaseous electric discharge device, a sealed tube having electrodes therein, and a fibrous silicate compound of alkali or alkaline earth metals disposed between said electrodes and between each of said electrodes and said tube.

4. In a gaseous electric. discharge device, a sealed tube having .electrodes therein, and a fibrous silicate compound of alkali or alkaline earth metals between said electrodes.

5. In .a gaseous electric discharge device, a sealed tube having electrodes therein, and a fibrous silicate compound of alkali or alkaline earth metals supporting and in contact with the active end of each of said electrodes in said tube.

6. In a gaseous electric discharge device, a sealed tube having electrodes therein, and a vitreous fiber adjacent and in contact with the active end of each of said electrodes as a supporting means therefor.

7. In a gaseous electric discharge device, a sealed tube having electrodes therein, a supporting means comprising a material in a finely divided condition between the active end of each of said electrodes and said tube, said supporting means being adapted to fuse with the electrode by a slight amount thereby creatinga bond between said means and said electrode.

8. In a gaseous electric discharge device, a sealed tube having electrodes therein, and a fibrous gas scavenging material immediately adlament the active end of each of said electrodes adapted to absorb the released gases normally occluded in said electrodes.

9. In a gaseous electric discharge device, a sealed tube having electrodes therein, and a. fibrous gas scavenging material completely encircling and in contact with the active end portion of each of said electrodes adapted to scavenge the released gases normally occluded in 4 said electrodes. I

10. In a gaseous electric discharge device, a sealed tube having electrodes therein, .and a finely divided fusible material in said tube adjacent and in contact with the active end of I each of said electrodes for slight fusion by the heat therefrom, said material upon slight fusion being adapted to release a gas scavenging element adapted to entrap and retain foreign gases present in said tube.

11. In a gaseous electric discharge device, a sealed tube having electrodes therein, and a finely divided slightly fusible material encircling and contacting the active end of each of said electrodes, said material upon fusing by a limited amount under heating and by its electrodes being adapted to release a gas absorbing element adapted to entrap and retain gases normally occluded by said electrode.

12. In a gaseous electric discharge device, a sealed tube having electrodes therein, and a fibrous compound of silicate and alkali or alkaline earth metals in said tube adjacent and in contact with the active end of each of said electrodes, said compound being adapted to partially fuse under the heat from said electrode, said compound upon fusion being adapted to release said alkali or alkaline earth metals, said alkali or alkaline earth metals being adapted to act as a scavenger for foreign gases after such release.

13. In a gaseous electric discharge device containing an amount of mercury, a sealed tube having electrodes therein, and glass wool means adjacent and in contact with the active end of one of said electrodes for entrapping a quantity of the mercury during inoperation of said tube whereby vaporization thereof occurs immediately upon reheating of said electrodes.

14. In a gaseous electric discharge device containing an amount of mercury, a sealed tube having electrodes therein, and a material containing an alkali or alkaline earth metal immediately adjacent and in contact with the active ends of said electrodes for partial fusion, and release of said alkali or alkaline earth metal by the heat thereof, said alkali or alkaline earth metal upon release being adapted to form an amalgam with a portion of said mercury during inoperation of said tube whereby an amount of said mercury will promptly evaporate upon subsequent re-heating of said electrodes.

15. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, and a support. for each of said electrodes comprising a fibrous slightly fusible material containing an alkali or alkaline earth metal, said support encircling each of said electrodes and covering in contacting relation a substantial portion of the outer surface of the active end thereof, said support upon slight fusion being adapted to release a quantity of said alkali or alkaline earth metal, said alkali or alkaline earth metal upon release being adapted to serve as a getter for foreign gases in said tube.

16. In a gaseous discharge device including an electron discharge cathode positioned to be bombarded by positive ions travelling thereto for further electron liberation, a screen of glass wool for said cathode encircling the emission end thereof, said screen extending along a portion of the length of said cathode and comprising a means for forcing the said positive ions to enter the interior of said cathode for neutralization.

17. In a gaseous electric discharge device including an electron discharge cathode positioned to be bombarded by positive ions travelling there to for further electron liberation, a screen of glass wool for said cathode encircling the emisslon end thereof and to extend forwardly thereof by an appreciable amount, said screen extending along a portion of the length of said cathode and comprising a means for forcing said positive ions toward the center of said cathode for neutralization.

18. In a gaseous discharge device, a sealed tube, an electron discharge cathode positioned in said tube to be bombarded by positive ions travelling thereto for neutralization, means for supporting said cathode in spaced relation with said tube, said means being composed of a silicate compound wool-like structure containing an alkali or alkaline earth metal encircling said cathode at the open end thereof, said wool comprising a screen for forcing said positive ions toward the center of said cathode for neutralization, said wool being adapted to partially fuse under the heat from said cathode and upon such fusion to release an amount of said alkali or alkaline earth metal, said alkali or alkaline earth metal being adapted to act as a scavenger of any foreign gases in said tube.

19. The combination as set forth in claim 18 wherein said means extends forwardly of the open end of said cathode by an appreciable amount.

20. In a gaseous discharge tube having an envelope enclosing a gas filling, an electrode disposed within said envelope and having a cylindrical outer surface concentrically spaced from said envelope, and a wrapping of glass wool covering the exterior surface of the active end portion of said electrode and substantially filling the space between the electrode and envelope, said wrapping of glass wool extending inwardly of the envelope beyond the active end of the electrode.

HARRY A. STONE.

FRANK SCHAEFER.