US1838458A

US1838458A - Electrical apparatus

Info

Publication number: US1838458A
Application number: US654645A
Authority: US
Inventors: Charles G Smith
Original assignee: Raytheon Co
Current assignee: Raytheon Co
Priority date: 1923-07-30
Filing date: 1923-07-30
Publication date: 1931-12-29
Anticipated expiration: 1948-12-29

Description

i C. G. SMITH ELECTRICAL APPARATUS Dec. 29, 1931 Original Filed July 50 1925 LOAD Patented Dec. 29, 1931 Bantu STAT S PAT Q F ciaasiisse, SMITH, or mnnronn, iviAssA oriusETrs,.-AssIGi\ oR, BY inEsnE AssieN arenas, T0 RAYTHEON me, or CAMBRIDGE, 'miissaennsnrrs, a CORPORATION or MASSACHUSETTS ELECTRICAL APPARATUS Application filed July 30,1923, s m No. 654,645. Renewed October 21, 1930.

The present invention relates to-electrical apparatus and more particularly to types'of electrical apparatus involving electrical conduction through a gaseous-medium;

It will be appreciated by those skilled in the art that one ofthe chief disadvantages of the usual forms of gaseous conduction-apparatus, Which involve the ionization of anelectrically stressed gaseous inediuinflies in the fact that continued. operation oflt he apparatus causes the discharge tobecoiiie-irregular and erratic. This erratic operation arises'partly from the formation of a layer of ionized. gas adjacent the Walls of the containing receptacle, the action of this ionized gas bein to electrically charge the receptacleat various points, thus giving rise to non uniform and varying potential gradients throughout the gaseous region. Furthermore, continued discharge in the region adjacent theTWalls of the recptacle causes the Walls-to become blackened or covered with a layer of conducting material, the formation of which tends not only to aggravate the erratic operation of the device; but also after long continued use, to often render the device practically inoperative.

The object of the present invention is to provide improvements in gaseous conduction devices of this general nature whereby regular and uniform operation of the apparatus may be secured.

In the usual constructions of gaseous discharge apparatus it has been found that the undesirable electrical charging of the receptacle arises from the fact that electrostatic lines of force which may be enabled to pass near the Walls of the receptacle ordinarily lie Within a gaseous region of'considerable magnitude. lines of force in a large gaseous'regioncauses ionization of the gas, from Which follow the charging of the receptacle and the consequent disadvantagesoutlined above. With the above object in View, however, I have discovered, that by restricting the gaseous re gion through which such lines of force may pass, gaseous ionization in this region may be substantially eliminated. Accordingly, one feature of the present invention contem- The presence of. electrostatic "ent invention, I 7

Although the features of the present in- 9 plates the provision of an electrical appa ratus'h ving electrodes so maintained-in a gas filled receptacle that the-gaseous regionsadjacent the Walls of the receptacle are of such restricted dimensions that ionizationis impossible. To this end, the Width of such restricted gaseous regions should be comparable to the means free path of electrons in thegas, that is so short that electrons traveling directly across such regions produce insufficient ionization to initiate substantial conduction. The mean free path of electrons, as herein connoted, is the average distance traveled by electrons Without ionizing impact with gas molecules (or atoms); I It is believed that by the restriction of the gaseous region adjacent the walls of the receptm'zle,- the operation of the present in vention depends largely upon theprinciples disclosed in theco-pending patent of Smith, No. 1,545,207, granted July '7, 1925, Which describes a novel type'of insu1atingappa ratus in which two electrodes are spaced so close together in a gas that gaseous ionization andconsequent conduction are impossible. A gaseous region of such retricted magnitude'may be said to present a practically infinite electrical resistance. therefore believed that the same principle holds in'the present invention in which the electrostati'c lines of force are constrained to pass through restricted gaseous regions.

It is I,

;]Other features of the invention consist of certain novel features of construction,

vantages "of which will be apparent to those skilledain the art from the. following 'description.

" The accompanying drawing illustrates the preferred form of a gaseous conduction tube embodying the several features of the pres vention are applicable to substantially any 1 type of gaseous conduction apparatus, the illustrated embodiment of the invention employs the type of apparatus described in the c'o-pending patent of Smith, No. 1,617,179,

granted Feb. 8, 1927. This application discloses a novel type of rectifying device comprising two electrodes spacedapartin a gas, one of the electrodes being provided with a hollow space in which is permitted the forma- I assemblies are conveniently supported upon a reentrant stem of the insulating receptacle and are preferably so constructed that the anode assembly is entirely surrounded by the cathode assembly, thereby preventing the discharge from affecting in any way the external partof the receptacle. However, the stem upon which the electrode assemblies are mounted is maintained in the region of a fairly intense electric field. According to the present invention, therefore, the electrodes are so mounted upon the stem that any electrostatic lines of force whichpass adjacent the stem are constrained to lie within a gaseous region of such restricted magnitude that ionization is prevented.

Referring particularly to the drawing, the preferred construction comprises a receptacle 2 consisting ofan external bulb 5 and a reentrant cylindrical stem 7, both being preferably of glass. The stem 7 is provided with 'a'partition 8 of the form shown to divide the stem into two parts, the upperpart cominunicating with the rarefied gaseous medium enclosed by the external bulb -5. The actual manufacture of the apparatus is carried out by mounting both electrode assemblies on the stem and thereafter sealing the stem to the external bulb portion after which the tube is exhausted in the usual manner. The tube may then be filled with any gas at reduced pressure but it is preferred to'use an inert monatomic gas such as helium. The anode assembly comprises the anode proper 10 consisting preferably of a carbon button, a support 12 for the button, an internal cylinder 1 1 and an external guard cylinder 18. The two cylinders are connected by an annular supporting member 20 having a flanged surface which is adapted to rest upon the upper part of the stem. To this end, it isdesirable-that the uppersurface of the stem should be accurately ground. In order to hold the anode assembly rigid, the upper end of the guard cylinder 18 is spun over the edge of'the carbon button 10, as indicated in the drawing. The supporting member 20 has a depending cylindrical portion 21 which is adapted to fit snugly against the internal surface of the stem and an upstanding cylindrical portion 22 which is attached to the cathode assembly includes the cathode proper which is constructed with a base portion 30 having an upstanding sleeve 32 communicating with a hollow space. enclosed by the hollow cylindrical portion 3a. The base 30 and the portion 84 are preferably constructed of carbonf The base 30 rests upon a flange 36 of 'a cathode guard cylinder 38 which is of such dimensions that its internal surface is spaced from the surface of the anode guard cylinder 18 by a distance which is so short that ionization between the two guard cylinders is impossible. The two parts of the cathode are connected together and supported upon the flange 86 by a flange member 10 to which a suitable wire a1 is soldered at diametrically opposite points, the wire being adapted to pass over the hollow portion 3d of the cathode. The guard cylinder 38 is supportedupon a guard ring 42 which is in contact at its lower end with the stem 7 and which is provided with a recess l at its upper end, this recess being comparable in width to the distance separating the stem 7 and the guard cylinder 18. Also the upper end of the guard ring 42 is spaced fromthe lower end of the guard cylinder 18 by an equally short distance. I According to the invention disclosed in the co-pending Patent No. 1,617,- 179, the parts are so disposed that the surfaces of the anode 10 and the cathode base 30 are also separated by a distance which is comparable to the mean free path of electrons in the gas. The cathode assembly'is rigidly maintained on the stem by means of a cylindrical member 16 which is provided with a lead wire 16 to the other.

The simple rectifying circuit shown in connection with the apparatus includes an alter- .nating current generator 52, a transformer 54:, the tube 2, and a suitable load, all connected as indicated.

It will be seen that inasmuch as the anode assembly is entirely surrounded by the cathring 42 and may thus ode assembly, the tube cannot be injuriously affected in any way by the discharge. The close spacing between'the guard cylinders 18 and 38 renders discharge impossible except between the active surfaces of the electrodes themselves. Furthermore, the glass stem 7 is not placed under an excessive electrical stress since the path afforded for electrical conduction through the glass extends from the supporting member 20 to the lower part of the guard be made sufliciently long to prevent any injurious efi ects within the glass itself. 7 According to the present invention, the lower portion of the guard cylinder l8 and the upper part of the guard ring 42 are each separated from the material of the stem 7 by such a short distance that any electrostatic lines of force which may pass within the included region are powerless to initiate ionization.

Although the illustrated embodiment of the invention is designed to prevent undesirable discharge adjacent the surface of the reentrant stem, it is understood that the stem is to be consioered as part of the containing receptacle and that the walls of the receptacle, as that term is used herein and in the mended claims are to be considered as including the surfaces of the stem or any other parts of the receptacle adjacent which any electrostatic lines of force may pass.

This application is in part a continuation of my Patent #1,617,179, granted February a, 1927.

The invention having been described, what is claimed is:

1. A gaseous discharge rectifier comprising a sealed container having a reentrant stem, said stem having a cylindrical portion extending inwardly into said container, a cathode and anode mounted on said stem in spaced relation to each other, one of said electrodes being supported by concentric meta-l cylinders, the distance between which is substantially equal to the thickness of the cylindrical portion extending from said stem, said concentric members being mountedrespectively on the inside and outside of said projecting portion, an annular member anchored between said concentric members and serving as a stop for the edge of said projecting portion and a spring connected to said electrode and serving as a lead therefor, pulling said electrode down to maintain said concentric members firmly against said projecting portion.

2. A gaseous discharge rectifier comprising a sealed container having a reentrant stem, said stem being provided with a cylindrical portion projecting inwardly, a cathode and an anode spaced apart therein and mounted on said stem, both electrodes being supported by concentric cylindrical metallic members, said anode being supported by two the external bulb portion ofsuch members engaging the inside and outside walls respectively of said projecting portion of said stem, an annular member between said anode supporting concentric members, joining said members and serving as a stop for the edge of said projecting stem portion, and a spring connected to the anode and serving as a lead therefor, pulling said anode, and said anode supporting concentric members downwardly into firm engagement with said projecting stem portion.

3. A gaseous discharge device comprising a sealed container having a reentrant stem, said stem having a hollow portion extending inwardly into said container, two electrodes mounted on said stem in spaced relation to each other, one of said electrodes being supported by metallic members, said members being mounted respectively on the inside and outside of said hollow portion, a member fastened between said metallic members and serving as a stop for the edge of said hollow portion, and means for maintaining said last named electrode and its supporting members on said hollow portion.

4. A gaseous discharge device comprising a sealed container having a reentrant stem, said stem having a hollow portion extending inwardly into said container, two electrodes mounted on said stem in spaced relation to each other, one of said electrodes being supported by metallic members, said members being mounted respectively on the inside and outside of said hollow portion.

A gaseous discharge device comprising a sealed container having a reentrant stem, said stem having a hollow portion extending inwardly into said container, a cathode and an anode supported on said stem, said anode being supported by a supporting member on said hollow portion, a projection on said sup porting member engaging a shoulder on said hollow portion, and means for holding said anode and supporting member withsaid projection against said shoulder.

gaseous conduction device comprising a hollow cathode with an opening therein, an anode having a surface presented to the interior of the cathode through said opening, a sealed container having a reentrant stem, said stem having a hollow portion extending inwardly into said container, a supporting member for said anode engaging the outside and inside. of said hollow portion, said cathode being supported from said stem in spaced relationship to said anode.

CHARLES G. SMITH.