US2374546A - Manufacture of electron discharge devices - Google Patents

Description

; April 24, 1945.

J. P. LAICO MANUFACTURE OF ELECTRON DISCHARGE DEVIC ES Filed Jan. 21', 1941 INVENTOR J R LA/CO 0mm auw Patented Apr. 24, 1945 Joseph P; Laico, Brooklyn, N. 1, -assignor, togBell Telephone Laboratories, :Incorporated, .New

York,N.=Y.,a corporationof New York t y -Application January 21, 1941,"SerialNo. sis-4101' (o1. zso-a'zrs) 5 Claims. This invention relates to the manufacture of .electron discharge devices, and more particularly i tomethods of manufacturing electron. beam dis- .;charge devices such,-for.exan1ple, as beam devices of the velocity, variation type.

. ,Electron beam discharge, devices of the type to which .this invention pertains usually ,comprise two or more electrodes in energy transferrin -relationlwithrthe electron beam. Theattainment, of desiredoperatingcharacteristics, efii- ;cient operation, and operation at. ultra-high. frenquencies requires thattheseelectrodes bemount- .edin exact predeterminedrelation. and extreme- .ly close to one: another.- ,lFor example, in some velocity variation devices, the requisite spacing :bGtWBB'I'LBIBCtIOdGS defining the input and. output gaps isextremely small and the allowable tolerances-are, but a few tenthousandths of anzinch and,.in cases-where these electrodesarev apertured, for exampleannular, the electrodes must be in exact alignment. Such. electrodesxmaybe mounted in spaced relationbyinsulating members, for example ofvitreouswmaterial, to-or in --which they aresealed.

The exact spacing of suchelectrodes mounted 1:.

,in this mannerheretofore has-beenextremely ,dificult'to obtain .due to the factthat exact .de-

termination ofthe spacing by viewing has been impossible and due to theifurther fact that-the working of the vitreous-materialand thecontraction and expansion thereof during-the mal:-

ingot-the seals-thereto has notbeen accurately controllable to: enable the realization within vextremely close limits of the ultimately desired space relationof the electrodes. l

One. object of this inventionis to facilitate the manufacture of electron discharge devices .in-

cluding a plurality of closely spaced electrodes. .More specifically, one object of i this invention is.-.,to facilitate the'mounting of a plurality of electrodesin an electron discharge device in exactralig-nment and -in accurate and extremely close space relation.

In accordance withone feature-of thisinvention, the several electrodes are provided with annular :mounting or supporting portions and tubular vitreous .members are hermetically sealedin coaxial relation to opposite faces of the mounting portions. The electrodes to,-be =-mou-nted .in..-adjacent relation are then fitted upon a tool-or guidewith thetubularvitreous members ,of the two in abutting relation, the tool locating the twoelectrodes in ,exact coax iallyarid allowing relative longitudinal movemembers are then heated to seal them together,

the necessary working of the vitreous material being accomplished Qhy relative longitudinal movement ofthe electrode. "The tool is so constructedthat the electrodes arelocated accurate- "lyin'th'e exact space relation desired, when the vitreous material cools andithe seal is formed.

The invention and the foregoing and other features thereof will be understood more clearly and fullyfrom' theffollowing detailed description with reference to the accompanying drawing in which:

"Fig; 1 is a view in elevationofanelectronbeam discharge device of the .velocity variation type constructed accordance with this invention, a portion of the device being shown in section to. illustrate'the'form andrelation of certain of the electrodes nore clearly;

' Fli 2. isfa detail view insection of a portion .of the discharge "devicev illustrated ,in Fig. 1,

showing the variousfelectrode andinsulator assemblies. to .be mounted, prior to the sealing together thereof; M

.Fi B is aidetail view insectionnf oneof the electrodes and a toolused inconjunction therewith duringthe. sealing of the insulating, membersthereto; H

Fig. 4' is, another ,detail view mainly insection illustrating the mounting of another. of theelectrodes during the sealing of. the insulatingmembers thereto;

Fig, .5, is still another detail view in-section il lustrating the mannen otpositioning several of the electrode and insulator assemblies during the Ijoining thereof;

, Figs. 6 and, 7.. are, fragmentary views. in, section illustrating other electrode assemblies constructed inaccordance with this, invention; and l i Fig. 8 is a viewhin section illustrating-another way of positioning electrode and insulatorunits duringthe joining thereof.

Referring ,now',.to the drawing the electron beam discharge device comprises an evacuated enclosing vessel having an, elongated cylindrical portion lll, an .anode or target electrode .ll

mounted near one end of the cylindrical portion In and ,anelectron. gunJZ, which, may be of the construction disclosed in Patent. 2,303,166, grantvedNovemberzr, 1942,, to Joseph P, Laico, mounted opposite the other-end of the cylindrical. portionlll,

Mounted between thelelectron gun, l2 and the shock: or ,target electrode H are.a plurality .of

coaxial electrodes .l3 to ll, inclusive, ,each of ,ment of-the electrodes. The abutting vitreous 56 which. inC udQSanafi m y a- -l c ppe tral frusto-conical portions 20, and the electrode l includes a central, annular inwardly curved portion 2!. The electrodes l3 and. M are spaced to define an input or control gap 22 and the electrodes l6 and I! are spaced to define an out-.

put gap 23.

The operating characteristics of thedevice are I dependent in a large measure upon thesegaps' For example, efli cient operation and electrical "positioning or guide member or tool, for example symmetry of the electrodes with respect to the beam whereby uniform transfer of energy between I the electrode and the beam may be realized re- ,quire that the electrodes bein exact coaxial relation. Furthermore, particularly at ultra-high frequencies, gaps of extremely short length and great accuracy, for example with tolerances-of the order of five ten thousandths of an inch, are required. Both the requisite exact coaxiality .and

accurate-close spacing are attained facilely in devices'constructed in accordance with this invention. v

As illustrated lar portion [8 of each of the electrodes l3 to H, inclusive, has hermetically sealed to opposite 'faces thereof lengths ofcylindrical, e. g., vitreous, tubing 24a and 2411 which are coaxial with one another and the electrode to which they are sealed. The sealing between the annular porin Fig. 2., in manufacturing de; vices in. accordance with this invention, the annutions I 8 and the vitreous tubing s and 241) may be effected as illustrated in Figs. 3 and 4.

As shown in the former figure, thefi'usto-co'nical,

member 20- of' the electrode l4 or it is fitted on ya metallic o-r insulating guide 25 which is mounted 'slidably on a rod 26 coaxial therewith and which may be supported between chucks, not shown. The electrode maybe clamped to the guide 25by a collar 21having an inner frustoconical wall conforming to the frusto-co-nical member 211 and which is detachably locked to the guide 25 by a hairpin shaped wire 28 having outwardly bent ends as shown. The vitreous tubings 24a and 2417 are positioned by the chucks, in coaxial relation with the rod 26 so that when the tubing, is hermetically sealed to the annular portion 18 by the application of. heat thereto in known ways, the coaxiality of the electrode and 28 is withdrawn and the guide 2 5 and collar 21 are removed as is also the guide 26; p

The seals between the electrode 15 and the lengths of tubings 24a andZl'b associated therewith may be made in thesame manner, as shown 29 and'detachably locked thereto by one or more spring wires Mlhaving-bent-over ends as shown.

.4. is completed the annularportion [8 of the electrode l5 extends hormal to the longitudinal axis in Fig. '4. The electrode I5 is mounted on a guide of the unit. After the seals'be'tween thisportion l8 and the insulating tubes 24a and Nb have been tioning member or tool have been constructed as described above, the units are joined to one another in a manner which assures the attainment of both exact coaxiality of the electrodes and accurate spacing thereof. These ends may be realized through the use of a of tungsten or stainless steel, which, as illustrated in Fig. 5, includes an end portion 32 having a surface which conforms accurately to the central portion 2! of the electrode, l5, a frustoconical portion 33 which fits accurately within the portion 20 of the electrode H1 (or IS), an end portion 34 accuratelyfitted within the cylindrical portion [9 of the electrode l3 (or IT) and an intermediate portion 35 forming a seatagainst which the electrode I 3 (or IT) abuts. The posiis .slidably mounted upon a rod 36. I

In joining the units, the electrodes Hi and IT together with the associated insulating tubes ma 'be'mounted upon the insulating member or tool with the tube 241) of the former inend-to-end relation with the tube 24a of the latter. The

facing ends of the two lengths of tubing are then heated, as by flames played thereon. to render them plastic, and these lengths are then sealed is possible; as is apparent, to allow the necessary working of the vitreous material at the plastic ends without altering the coaxial relation of the two units being joined. After the vitreous material has been worked properly, the electrode I6 is positioned so that the frusto-conical portion 20 thereof is firmly fitted upon the port on 33 of the tool andthe electrode I1 is moved toward the between the abutting tubings 24a and Nb forms.

'The portions 33 and 35 are so dimensioned that when the electrode ll abuts the seat therefor. the spacing between the electrodes l6 and IT is exactly that desired for the gap 23. I A seal is then made in a similar mannerbetween thetub ng 24b associated with the electrode l6 and the tubing 24a associated with the electrode l5,the portions 32 and 33' of the tool being so dimensioned'that when the electrode members 2i and 20 respectively are in firmlengagem'ent therewith, the electrodes are in exactly th'e'space relation desired in thecompleted device. 7 After the three electrode-insulator units have been joined as described, the tool and rod 36 are withdrawn. A similar assembly is formed in like manner of the electrodes 13 and "arid the. insulating tubings' associated therewith. The

the two'assemblies are mounted in coaxial relation," and the tubing 24a associated with the elec trode I4 is joined to the tubing 2% associated with the electrode iii. The two assemblies may bei located, longitudinally 'gduring .the making of .the: final seahby an 'externalyspaocrz :engagingthe x annularportionsl I 8 of the aelectrodes r I4 and; I5.

*ItaWill be. apparentdthat im the assembly Tthus formed, all of r the. electrodesrare inexact coaxial ;re1ation: andthe spacingsybetweemadjacent 291E- trodes tare .accurately; fixed so, that. a; device 10f i which this assembl forms ,ag'part will have: the

shown, for example, in Figs. 6 and 7. As shown in Fig. 6, the endmost electrodes of the assembly include central frusto-conical portions 31, the

central electrode includes an annular central portion 38 and the intermediate electrodes include centrally apertured dished portions 39. As shown, several of the electrodes may be provided with an annular corrugation 40 to allow expansion and contraction thereof during the fabrication and operation of ithe device and thereby to prevent the setting up of deleterious stresses at the seals between the annular disc portions l8 of the electrodes and the tubular portion III of the enclosing vessel and also to minimize variations in the space relation of the electrodes.

In the construction illustratelsl in Fig. '7, the central electrode is an annular disc 4| and the other electrodes are provided with coaxial central cylindridal portions as shown.

In cases where the electrodes are of such configuration that the longitudinal spacing thereof cannot be fixed by a guide or tool of the general construction shown in Fig. 5, apparatus of the construction shown in Fig. 8 may be employed during the joining of two electrode-insulator units to one another. In the construction illustrated in this figure, the electrodes comprise central frustoconical portions- 42 in end-to-end relation and annular portions I8 sealed to vitreous tubings 24a and 24b in. the manner described heretofore. The two electrodes, together with the insulating tubing associated therewith, are mounted in coaxial relation by a cylindrical guide 43 having openings in its wall through which spacers 44 extend, the spacers being dimensioned accurate- 'ly so that when the electrode portions 42 abut thereagainst, these portions will be in exactly the space relation desired in the discharge device. The spacers 44 are carried by resilient sulpporlts 45 fitting in internal grooves in the guide 43. The guide 43 is slidably fitted upon a rod 46 which is insertable between the supports 45 and when thus inserted separates the spacers 44 so that they project from the guide 43. After the tubings 24a and 241) are sealed to one another, during which operation the electrode pore tions 42 are located accurately with respect to one another by virtue of the abutment thereof against the spacers 44, the rod 46 is withdrawn, the spacers 44 are forced within the guide 43 by pressing the supports 45 toward each other, and the guide 43 is withdrawn. In the assembly thus formed, it is apparent that the two electrodes are mounted in exact coaxiality and are accurately spaced the distance desired.

Although specific methods and apparatus have been described, it will be understood that they are but illustrative and that various modifications may be made therein without departing from 75 the; scope andaspirit of this. :inventiomasodeflned l in theaappended'claims. What is claimedzis: M l

In the manufacture of l welectron discharge 1 devices includinga tubular 1 insulating member 1 and a: plurality "ofaelectrodes wwithin.said; member and having conductive .portions uhermetically sealed to-said. member the method which com- ,prises, sealing a. tubular, lengths ,of; insulating rma- .terial to. opposite? faces-ofi each iofrsaid conductive portions, mountingseveral, of; the assembliesathus formed in alignment, axially movable with respect to one another and with tubular lengths of successive of the assembliesin abutting relation, and

hermetically sealing the abutting tubular lengths to one another.

2. The method of constructing a unitary assembly for electron discharge devices including a tubular insulating member and a plurality of electrodes Within said tubular member and having conductive portions sealed thereto, which method comprises sealing coaxial tubular lengths of insulating material to opposite faces of each of said conductive portions and in coaxial relation therewith, mounting several of the assemblies thus formed in coaxial relation, longitudinally movable with respect to one another and with the tubular lengths of successive assemblies in abutting relation, locating said assemblies so that the electrodes included therein are in fixed, coaxial space relation, and hermetically sealing the abutting tubular lengths to one another.

3. In the manufacture of an electron discharge device including a tubular insulating member and a plurality of electrodes within said tubular member and having annular disc portions hermetically sealed to said member, the method of assembly which comprises sealing tubular lengths of insulating material in coaxial relation to opposite faces of each of said disc portions, mounting several of the assemblies thus formed in relative longitudinally movable relation upon a guide having portions for locating the assemblies in coaxial relation and for determining the spacing between the electrodes in said assemblies, with tubular lengths of successive assemblies in abutting relation, softening the ends of said abutting tubular lengths, shifting adjacent assemblies longitudinally to engage the electrodes thereof with said spacing determining portions, sealing abutting tubular lengths to one another, and withdrawing said guide.

4. The method of manufacturing an electron Hg discharge device including a tubular insulating portionand a pair of electrodes within said portion, each of said electrodes having a central portion and an outer annular disc portion hermetically sealed to said insulating portion, which method comprises sealing tubular lengths of insulating material in coaxial relation to opposite faces of each of said disc portions, mounting the assemblies thus formed upon a guide having coaxial portions adapted to fit said central portions of said electrodes and having thereon locating means for positioning the electrodes in predetermined relation, said assemblies being mounted on said guide so as to be relatively movable longitudinally and with one tubular length of one assembly in juxtaposed relation with one tubular length of the other assembly, heating the juxtaposed ends of said tubular lengths to render them plastic, sliding said assemblies longitudinally on said guide until the electrodes therein abut said locating means, hermetically sealing said juxtaposed ends to ether, and withdrawing said guide.

5. In the manufacture of an electron discharge device including a tubular vitreous member and a pair of spaced electrodes within said member, each of said-electrodes having a central apertured portion and an annular supporting portion hermetically sealed to said vitreous 'member, the

method which comprises sealing tubular lengths of vitreous material to one iace of each of said annular portions, mounting the assemblies thus formed in coaxial and longitudinally movable relation upon a guide having portions adapted to fit within said aperturedportionsof said elec-- To another, and withdrawing said guide.

JOSEPH P. LAIco.

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