US2879428A

US2879428A - Electron tube

Info

Publication number: US2879428A
Application number: US524676A
Authority: US
Inventors: Paul D Williams
Original assignee: Eitel Mccullough Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1955-07-27
Filing date: 1955-07-27
Publication date: 1959-03-24
Anticipated expiration: 1976-03-24

Description

Mmh 24, 1959 P. D. WILLIAMS ELECTRON TUBE Filed July 27. 1955 ATTORNEY United States Patent O ELEcTRoN TUBE Paul D. Williams, Menlo Park, Calif., assignor toEitel- McCullough, Inc., San Bruno, Calif., a corporation of California Application `urly 27, 1955, Serial No. 524,676

5 Claims. (Cl. 313-247) to the adjacent ceramic section in a manner which willl accommodate the distortion'caused by the unequal coeticients of expansion ofthe anode and .theadjacent ceramic section. f

',Another object of the invention is to provide yin conjunction with the improved connecting arrangement a simplified arrangement for shielding the cerramicsection adjacent the anode from electron bombardment.

A further object of the invention is to provide a simplified arrangement for supporting both the cathode and its heater on one of the metal rings envelope.

The invention possesses other objects and featurts ofy advantage, some of which, with the foregoing, will beset forth in the following description of lthe invention. It is to be understood that the invention is not limited to the disclosed species, as variant embodiments thereof are contemplated and maybe adopted within ythe scope of the claims.

Referring to the drawing, thesingle gure is a vertical which makeup the tube The electron tube includes an external copper anode 6 positioned in end-to-end relationship with the longer ceramic ring 2, so that the walls of the anode complete the envelope structure. If desired, the anode may be surrounded by a conventional cooler of the type having fins radiating outwardly from the anode. The lower rim of the anode is supported on the upper rim of the ceramic ring 2 and is secured in place by the connecting ring unit 8. Ring unit 8 consists of a lower ring 9 and an upper ring 10, the lower ring having a flat portion 11 which is brazed to the upper metalized end of the ceramic ring 2. The upper connecting ring 10 has a at portion 12 which is brazed to the side of anode 6. YThe outer ends of rings 9 and 10 are arc welded to form the metallic bond 14 and thus form an air-tight connection between the anode and ceramic ring 2. It will be noted that rings 9 and 10 are separated intermediate their inner and outer ends to form an annular space 16. The rings 9 and 10 are preferably made from thin deformable mate rial such as copper having a thickness of .010, and the upper ring 10 .is curved intermediate its ends in order to accommodate distortion of the connecting unit 8 caused by radial movement of the side wall of the anode relative to the ceramic ring 2 due to the unequal coetcients of expansion of the anode and ceramic ring.

The preferred method of assembling the improved electron tube is irst to assemble all of the parts with the exception of anode 6. -At this stage, the lower connecting ring 9 has been bonded to the vceramic ring 2, and the upper connecting ring 10 has been bonded to the anode 6. Next the anode is placed in position on the ring 2 and the outer ends of connecting rings 9 and 10 are then bonded at 14 to complete the tube envelope. The final step is to evacuate the tube and pinch olf the exhaust tubulation 18 in the usual manner. If desired, a cup-shaped cap may be inverted over the outer end of tubulation 18 and brazed to the upper end of anode 6 in order to protect the tubulation from damage. It will be understood that when the anode 6 is secured in position prior to the exhaust step, the annular space 16 in the connecting unit 8 is lled with air. If this condition were allowed to exist, the trapped air could slowly leak sectional view of a diode embodying the improvements of the invention..

`In terms of broad inclusion, the improved electron tube structure comprises aV plurality ofceramicrings and flat metal rings arranged alternately in a stack with the ends ofthe ceramic rings being `metalized and metalbouded to the adjacent metal rings. ,An external anode forms al section of the Atube envelope adjacent one of the ceramic rings and is joined to, theadjacent ceramic ring by a deformable air-tightV connection,I -with La. shielding ring extendingfrom the connection partway along Athe 1'n` side of the ceramic ring. A cathode land heater therefor are ,positioned in the tube envelope and are A,supported by the iiat metal rings, the cathode and one of the heater supports being joined to a single one of the flat-rings.

,In greater detail and referring. 4to the drawing, the

evacuated tube envelope is of generally cylindrical shape having a side wall structure comprising two ceramic rings p 1 and ,2 and two flat metal rings'3 and 4 'arra1rged" all` ternately -in a stack. The ceramic is preferably a high refractory body such as alumina, and the ends of the ceramic ringsrare .metalizedwby a. suitablel metaliaing pro cedure such asthe 'molybdenummanganese 'powder sintering process. The lat metal rings 3 and '4 are relativelyl thin, having a thickness of about .010"and are of a materialhaving good electrical conductivity such as copper. The ceramic ringsV and the metal rings are brazed together, using high temperature' such ascopper-silver or the-like.

brazing `alloys between the lower rim of anode 6 and the at portion 11 of connecting ring 9 to destroy the tube vacuum. AIn order to prevent this condition, the annular space 16 is vented vto the interior of the tube by means of one or more notches 19 in the rim of anode 6 so that the annular space 16 will be exhausted during evacuation of the tube.

In order to protect the ceramic ring 2 from .electron bombardment adjacent its upper end, a shielding ring 20 f isprovided, the upper end of ring 20 being flanged outwardly to ,reston the hat portion 11 of connecting ring-9 and to space the ring 20 'inwardly'fromthe ceramic ring 2l It will be noted that the internal diameter of. anode 6 is greater than the internal diameter ofv connecting ring 9 in order to provide ample seating for the upper flanged end of shielding ring 20, which is held in place by brazing to the flat portion 11 of ring 9.

The tube includes a cathode 22, preferably of the oxide coated type and having the appearance of antinverted cup. A cathode skirt 23 is attached to the bottom of cathode 22 and in turn is mounted on a cylindrical cathode support 24. Cathode support 24 has an outturned ilanged portion 25 on its lower end Vwhich -is seated on an inward extension of the metal vring 4 and cathode. The heater iilament 27 is mounted on two supports, namely, the coaxial center support 28 and the outside support 29. The center support 28 is connected to Patented Mar. 24, 1959' the "lowermost'metl lring-3 `bymeans of the upwardly directed funnel portion 31 or-v ring 3,- thel center-support 28 being brazed to the neck of funnel portion 31. The outside heater support 29 is conveniently mounted on metalv ring i4 whiclif supports thefcathode, and* for-*this purpose ring 4 is pr'ovid'edwithfan upwardly extending.`

tubular`boss33,`to which the support 29 is firmly spot weldedz The metal-rings'3 and 4 are designed to serve not only as supports for cathode 22 and heater 27 but also as terminals for these members, and for this latter purpose each of -the rings 3 and 4 is provided with a pluarality of

tabs

35 and 36, respectively, extending outwardly from thetube envelope and spaced equally .around the circumference of `the envelope. In the preferred embodiment of the disclosed tube, six'tabs are provided on each'of the rings 3 and 4, but any other suitable number of tabs may be employed It will be understood that the single drawing figure is a vertical section of the tube taken-on -a lplane passing between adjacent tabs so that the tabs appear-solid'ratherf than in' section. The tabs 35and -36' are" aligned with each other longitudinally of the-tubefsotha-t' the tube mayk be inserted axially into a socket having two rings of inwardly directed tabs corresponding totheoutwardly directed tabs 3S and 36. After Athe tube has been inserted axially into such a socket, it may be rotated'until

tabs

35 and 36 overlap the socket tabs. It is customary in the describedtype of socketing to provide the tube socket with a spring which acts to resist insertion of the tube into the socket and thus holds the

tube tabs

35 and 36 in firm engage ment with the corresponding socket tabs. Although the described socketing arrangement is preferred, it will be understood that other types of socket ttings could be connected torings 3 and 4 in place of

tabs

35 and 36.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. An electron tube comprising a generally cylindrical envelope having a plurality of ceramic rings and fiat metal rings mounted alternately in a stack in axially abut` ting relation, said ceramic rings having metalized ends and metallic bonds uniting said ceramic and metal rings together, a cathode mounted concentrically within said tube envelope, a generally cylindrical support for said cathode extending upwardly from one of said metal rings internally of said envelope, the lower end of said cathode support having an outwardly extending tlange to provide a substantial base in contact with said one metal ring, a heater inside said cathode, and a support for said heater connected to said one metal ring internally of said cathode support, said one metal ring having a tubular central boss to provide 'substantial contactarea with the lower end of said heater support.

2. An electron tube comprising a generally cylindrical envelope' having a "plurality of ceramic ringsA and flat metalrings'mounted alternately in a stack, the ends of' said `ceramic "rings having' vmetal coatings thereon and metallic 'bonds uniting said ceramic and metal rings together, an electrode'and' a heater `for the electrode in said envelope,su'pports to said electrode and heater extending from said metal rings, an anode having a generally cylindrical wall portion forming a section of the envelope, said anode wall positioned adjacent one of said ceramic'rings in end-to-end relationship therewith, a metal ring unit joining said anode /wall and the adjacent ceramic ring, said metal ring unit comprising two metal connecting rings, a rst one of said connecting rings having a tlatl -portion seated on the end of said one ceramic ring adjacent said anode, a metallic bond between said flat portion of the rst connecting ring and the end of said one ceramic ring, the end of said anode wall seated on'said flat portion'of the rst connectingring, a second one of said connecting rings having its inner end portion joined to said anode, said rst and second connectingrringsextending outwardly of said envelope and a 'metallic bond joining the outer ends of said connecting-mingstogether, said connecting rings being spaced from each other between their outer joined ends and their inner at portions forming an annular space, and said anode wall having a passageway therethrough connecting said annularV space with the interior of the envelope.

3. An electron tube comprising a generally cylindrical envelope'fhaving;a plurality .of ceramicv rings and atv envelope `and joining said anode and the adjacent ceramic ring-together;fsaid'connectingl ring comprising a ilat portion seated on the end of the ceramic ring adjacent the anode; said ila't-r portion offtheconnecting ring extending inwardly of said 'anodewalL and a shielding ring secured to saidinwardly extending portion of the connecting ring, said'v shielding 'ring extending coaxially along the inner wall 'of said one ceramic ring and spaced inwardly therefrom.

4.`An electrontube comprising a generally cylindrical envelope'having 'a plurality of ceramic -rings and at metal rings lmounted alternately in a stack, the ends of said ceramic l'rings'having -metal' coatings thereon and metalliclbondsfuniting said ceramic and metal rings together,'"an"electrode and a heater for the electrode in said envelope,supports to vsaid electrode and yheater extending from said metal rings, an anode having a generally cylindrical wall portion forming a section of said e11- velope,'said"an'ode wall positioned adjacent one of said ceramic rings 'in end-to-end relationship therewith, a connectin'gringl unit joining'said anode and the adjacent ceramic ring'tog'ether and'forming an annular space around the outside of saidI anode wall, said anode wall having a passageway 'therethrough 'connecting said annular space with the'inside" of the tube envelope, said connecting ring comprising a ilat'portion positioned between the end of the anode wall and the end of the adjacent ceramic ring, said 'dat portion of the connecting ring extending inwardly of the ano'de wall, and a shielding ring connected to said inwardly extending portion of the connecting ring, said shielding ring extending coaxially along the inner wall of theadjacent vceramic ring and spaced inwardly therefrom.

5.l An 'electron tube having an'envelope comprising a ceramic i'ingg'anV anode in the rform of a metal ring coaxial 'withisa'id 'fce'ralmic 'ring adjacent one end of said ceramicring'and 1a "flexible metal' connecting ring unit joining'saidf'end of said ceramic ring to the adjacent end of's'aid metal'ring'jone end 'of said connecting ring unit being sealed'tosai'd ceramic ring,` the other end of said connecting ring unit 'being sealed to said metal ring, the intermediate portionof said connecting ring unit extending outwardly'of said envelope to provide an annular space, saidmetal ring and said ceramic ring being supported on each other against axial movement toward each other, one of said ringshaving a passageway through the wall thereof connecting'said annular space formed by said connecting-ringfunit with `the interior of said envelope.

References Cited in the tile of this patent UNITED STATES PATENTS 2,419,578* Litton Apr. 29,' 1947 2,644,907 Drieschman et al July 7, 1953 n2,721,290 Dorgelo Oct. l18, 1955 2,722,624 Doolittle r Nov. 1, 1955