US2609517A

US2609517A - Ultrahigh frequency electron tube

Info

Publication number: US2609517A
Application number: US165256A
Authority: US
Inventors: Jack A Mccullough
Original assignee: Eitel Mccullough Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1950-05-31
Filing date: 1950-05-31
Publication date: 1952-09-02
Anticipated expiration: 1969-09-02

Description

p 1952 J. A. M CULLOUGH ULTRAHIGH'FREQUENCY ELECTRON TUBE 2 swans-41mm 1 Filed May :51, 1950 VINVENTOR. :14 CA A. Ms CULLOUGH MG ZL 7 A'TToeA/E structure it is thus possible to design high power tubes in the ultra-high frequency range.

The side walls of the envelope have insulator sections 6 of a suitable insulating material such as glass or ceramic sealed between suitable metallic rings, which rings are'aligned in pairs to provide a pair of cathode terminal rings '1 at the lower ends of the walls, a pair of anode terminal rings 8 at the upper ends of the walls, and a pair of grid terminal rings 9 intermediate the ends. The several rings have offsets so that the side walls diverge toward the upper portion of ture of my tube construction is that the inner and outer side walls may be separately fabricated assimple .cylindersprior to assembling the envelope so that the various glass-to-metal seals incorporated in the side walls may be readily madein. an ordinary glass lathe.v

After the side walls have been completely fabricated the inner wall is inserted within the outer wall, whereupon these parts are ready for further assembly of. the envelope. The several ring shaped electrode assemblies, including anode 2, cathode 3 and grid arealso separately fab: ricated as complete units and are so designed that they may be inserted between the side walls, which provides a simple and'effective procedure for making the tube.

Cathode 3 may embody any conventional type of electron emitter material, such as thoriated tungsten or a coating of barium and strontium oxides, the oxide type of cathode being wellv suited for my tube construction and therefore preferred. The ring-shaped cathode is conveniently formed as a circular channel stamped from a metal such as nickel, which channel presents a fiat face for-receiving the oxide coating toprovide the active surface of the cathode facing the grid. The cathode is supportedby a ring-shaped header l0, also formed as a circular channel stamped from suitable sheet metal, having a centerrib l l to which the cathode piece is connected,

and also having outwardly and downwardly exv tending supporting flanges I6. The cathode as sembly includes a heater which preferably com-. prises a flat spiral coil l2 embedded ina suitable insulating material is located in the channelshaped cathode. One end of the heater wireis connected to the cathode mount and the other end is brought out by a lead It sealed through the hcader.

The completed cathode assembly is insertedbetween the sidewalls so that downwardly extending flanges I6 of the header register with the lower pair'of terminal rings 1. This cathode assembly which forms the bottom wall of the envelope is then fixed in position by fused metallic bonds, as by brazes I! along the registering edges of flanges l6 and end rings I. i

.The flatring-shaped grid is fabricated in any suitable manner, as by wires stretched across a pair of retainingrings [8. The grid is supported 4 along both of its peripheral edges by circular metal flanges l9 having upturned lips or fingers engaging the intermediate pair of terminal rings il. This grid assembly is insertable between the walls from the top of the envelope. The grid-tocathode spacing isestablished by apair of concentric spacer rings 2! of suitable insulating material such as glass or ceramic, a material having a low coefficient of thermal expansion such as quartz, being preferred. These spacer rings are interposed between the grid and cathode, preferably between the supporting flanges l9 and I6 which.v flanges are shaped with circular flats or ledges to provide seats for holding the spacer rings concentric. The spacers 2! are placed in position and then the grid assembly is inserted and lowered down against the spacers.

,Such arrangement not only facilitates asa sembly of the tube but aiso provides an excellent meansfor establishing very close and accurate spacings between the electrodes. For example, the parts may be very accurately dimensioned, as by' precision grinding the spacer rings to size, to set the electrode spacing within a fractionofa thousandth of an inch. Such precision is especially important in ultra-high frequency tubes where the electrodespacings are very small, particularly at the grid-to cathode spacing which is most critical in tubes of this kind.

After the grid assembly has been brought down firmly against the spacers 2| the grid flanges l9 may be fixed to terminal rings 9 as by spot weldmg I prefer, however, to maintain connection between these parts by frictional contact for reasons later discussed.

Ring-shaped anode 2 is preferably of the external anode type machined of a suitable metal such as copper for good heat conduction. Its inner portion terminates at a fiat face providing erably includes the exhaust tubulation 23 com-j municating with the interior of the envelope through passage 26, the tubulation being pinched off at tip 2'5 after evacuation of the envelope.

The completed anode assembly is mounted by insertion between the side Walls and forms the top wall of the envelope. The grid-to-anode spacing, while usually wider and not as critical as compared to the grid-.to-cathode spacing. is nevertheless preferably established by a second pair of internal'concentric spacer rings 21 of in Spacers 2 1 are inserted after the grid assembly and then the anode assembly is lowered down against the spacers. When firmly seated the anode assembly is fixed by fused metallic bonds such as brazes 28 along the registering edges of flanges 22 and end rings 8. The grid assembly is thus positively locked in place between the anode and cathode without requiring fixed con nections at grid terminal rings 9. All of the electrode spacings are thus established and financed 31i ructure? .na ieli masr cur n,

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While'amany of the improvements described are particularly applicable to the annular type of tubelitiis understoodthat certain features su'ch astthestru'cturefor establishingfand maintaining close electrode spacingsmar/The incorporated in' 'other types'of-tubes'suchaatubes of'ithe'cnionventionaljpylindricalwrtubularfihape.

""I- claim:

1. An electron tube comprising an envelope having a circular side wall, a metallic terminal ring on the side Wall, an electrode fixed adjacent an end of the envelope, an electrode extending transversely of the envelope axis and slidably 1th afliskelike :eisealingcsurfaces engagin ztheirtermmali ringr and:

gainstgtneq internosefd;spaccrsfll. The

d at ea wraa'senressextetcanardethercathodeaiz ring shapecl electroderrfixe of i-insulatingamateria anorlagpairs ofigmetal-lic terminakrringsflon insulatin materialrwithinz'the;emtelopezhetween thefelectrddes tozesta'blislr thezspac-ing M rtha-slick ableiielectrode f-rormsaidsfixedeelectrode.

L11. zi'An qzelbtmn; tubezncomprismgaanezannmar 'enveloperhaving: concentriciirmer andccuteniside wallssxmetallimterminaltringsrzpndtheesidermaifls; 'diacent or thecenvelopeaaaingsshapeda lect'mdeeextexid-v ing transversely of the envelope axisgsamd slid'ahly engaging xthenterminalirings;aandnspacernrings 'awithinnthecenveiopeiabetweemthezelectrodesitorestablislrzthesspacingsof the; s'lidableaelectndde; fromcsaidzzfixedee'lectrode;

a electron tnbeicompri'singram armirlareenwelopev inaszirzgv concentric innertriandrznuternside wallsaringeshaped electrodes haningiopposedzaciti-veusurfaces:supportedgahetweerrcthezcsideawalis spacer: 'ringsimf insulating vmaterial withirrz'ithe :envelopaeandrintenposedibetweeneizhecelectmdes,

italsideawalls, metall-ice supportingifiangescom he cathodegconnecteditma- 'pairwnofszsaid criminal ringswmetallicrsupportin flangesron: he connectedz-toa\secondmair; of :said terminal-rings, metallic supporting:fiangeszmettheianodeconnected toza ;thi-rd ispain;of .saidwterminalr ,aa nail'sofaconcentricespacer.ringszofcinsulatingcma terialwvithinacth "envelope betweenasaidratlangesiof the: grideandecathodc; the,rconnectionsicbetmeen the; grid 58 111 1 mines-flanges: and: saidcsecond: 118111 of terminalzrriri snbeing firictiona ...contacts,7r and prin ?means rpressing agridatowardczthe c thode. 1 Ameiectron"tube;comprisingsaanisa'nnulansmq re 196 havinge-izconcentricinnemand onterzeside allsiii l :shapedrelectrodes?havingcopposedeace tive surfaces including a cathode and anodeapairs 'ofametallic ;terminal.-.z rings.ron :thecends-rfof -said walls, metallic:supporting'flanges'sonzthezrca-thode registerinamiththe terminal :ringsratronezend; 6! the? envelope, metallicrsupporting:flangeszonithe anode z-registeringi-with vthe:terminal: ringsratrzthe other rend 10i athe Jenve'lope, sand insed: metallic bonds rauniting 'rsaidxiflanges'iwvithi-ctherrrespective terminal-Tings. 1

1"?mm electron tube comprisina an annularenvelope 'having concentric inner and o'uter side walls, ring-shaped electrodes having opposed active surfaces including a cathode and grid and anode, pairs of metallic terminal rings on the ends of said walls, metallic supporting flanges on the ,Siid

cathode-registering with the terminal rings at one end of' the envelope, metallic supporting flanges on the anode registering with the terminal rings at thev other end of the envelope, fused metallic bonds uniting said flanges with :the respective terminal rings, another pair of terminalrings on said walls intermediate the ends thereof, and metallic. supporting flanges on the grid connected to said last mentioned pair of terminal rings.

8. 'An electron tube comprising an annular envelopehaving concentric inner and outer side walls, ring-shaped electrodes having opposed active surfaces including a" cathode and. grid and anode, pairs of metallic terminal rings on the ends ofsaidwalls, metallic supporting flanges on the cathode registering with the terminal rings at one end of. the envelope, metallic supporting flanges on the anode registering with the terminal rings at the other end of the envelope, fused metallic bonds uniting said flanges with the respective terminalrings, another pair of terminal rings onsaid walls intermediate the ends thereof, metallic supporting flanges on the grid connected tor-said last mentioned pair of terminal rings, and spacer rings of insulating material within the envelope and interposed between the electrodes.

9. An electron tube comprisingan envelope having concentric inner and outerside walls, pairs of metallic terminal rings on the upper and lower ends of said walls, another pair of metallic terminal rings on said walls intermediate the ends thereof; a ring-shaped cathode electrode assembly insertable between said walls and having metallic supporting flanges connected to the lower pair of terminal rings; a ring-shaped grid electrode assembly. insertable'between said walls and having metallic supporting flanges connected to the intermediate pair of terminal rings; and a ring-shaped anode electrode assembly insertable between said walls and having metallic supporting flanges connected to the upper pair of ter-' minal rings.

I 10. An electrontube comprising an envelope having concentric inner and outer side walls, pairs ofmetallic terminal rings on the upper and lower ends of said walls, another pair of metallic terminal rings on said walls intermediate the ends thereof; a ring-shaped cathode electrode assembly insertable between said walls and having me tallic: supporting flanges connected to the lower pair of terminal rings; a ring-shaped grid electrode assembly insertable between said walls and having metallic'supporting flanges connected to the intermediate pair of terminal rings; a ringshaped anode electrode assembly insertable between said walls and having metallic supporting flanges connected to the upper pair of terminal rings; and concentric spacer rings of insulating material interposed betweenthe grid and cathode assemblies.

- 11. An electron tube comprising an envelope having concentric inner and outer side walls, pairs of metallic terminal rings on the upper and lower ends of said walls, another pair of metallic terminal rings on said walls intermediate the ends thereof; a ring-shaped cathode electrode assembly insertable between said walls and having me tallic supporting flanges connected to' the lower pair of terminal rings; a ring-shaped grid electrode assembly insertablebetween said walls and having metallic supporting flanges connected to the intermediate pair of terminal rings; a ringshaped anode electrode assembly insertable between'said' walls and having metallic supporting flanges connected to the upper pair-of terminal rings; and concentric spacer rings of insulating material interposed between the grid and cathode assemblies the connections between the flanges of the grid assembly and said intermediate pair ofterminal rings being frictional contacts.

12. An electron tube comprising an envelope having concentric inner and outer side walls, pairs of metallic terminal rings on the upper and lower ends of said walls, another pair of metallic terminal rings on said walls intermediate the ends thereof; a ring-shaped cathode electrode assembly insertable between said walls and having metallic'supporting flanges 5 connected to the lower pair of terminal rings; a ring-shaped grid el'ectrode' assembly insertable between said walls and having metallic supporting'flanges connected to the intermediate pair of terminal rings; a ringshaped anode electrode assembly insertable be tween said walls and having metallic supporting flanges connected to the upper pair of terminal rings; concentric spacer rings of insulating material interposed between the grid and cathode assemblies;-the connections between the flanges of the grid assembly and said intermediate pair of terminal rings being frictional contacts, and spring means pressing the grid assembly toward the cathode assembly.

13. An electron tube comprising an envelope having concentric inner and outer side walls, pairs of metallic terminal rings on the upper and lower ends of said walls, another pair of metallic terminal rings on said walls intermediate the ends thereof; a ring-shaped cathode electrode assembly insertable between said walls and having metallic supporting flanges connected to the lower pair of terminal rings; a ring-shaped grid electrode assembly insertable between said walls and having metallic supporting flanges connected to the intermediate pair of terminal rings; a ringshaped anode electrode assembly insertable between said walls and having metallic supporting flanges connected to the upper pair of terminal rings; concentric spacer rings of insulating material interposed between the grid and cathode assemblies;'the connections betweenthe flanges of the grid assembly and said intermediatepair of terminal rings being frictional contacts, and the connections between the flanges of the cathode and anode assemblies and said end pairs of terminal rings being fused metallic bonds.

. JACK A. 'MCCULLOUGH.

REFERENCES orrnn The following references are of record in the file of this patent: V o

UNITED STATES PATENTS Number Name Date 2,025,461 Leonard, Jr. Dec. 24,1935 2,409,855 Hillyer, Jr. et a l. Oct. 22,1946 2,459,277 Halstead et al Jan.'18,-1949 2,459,859 Weston Jan. 25, 1949 2,471,037 Law May 24, 1949 2,496,003

' Eaves Jan. 31,1950