US2534548A

US2534548A - High-power water-cooled electron discharge device

Info

Publication number: US2534548A
Application number: US68346A
Authority: US
Inventors: Clifford E Fay; Douglas A S Hale
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1948-12-30
Filing date: 1948-12-30
Publication date: 1950-12-19
Anticipated expiration: 1967-12-19

Description

Dec. 19, 1950 Filed Dec. 3o, 1948 C. E. FAY ET Al. 2,534,548

HIGH-POWER WATER-COOLED ELEcTRoN DISCHARGE DEVICE 4 sheets-sheet 1 ATTORNEY Dec. 19, 1950 I c. E. FAY ETAL HIGH-POWER WATER-COOLED ELECTRON DISCHARGE DEVICE.

4 Sheets-Sheet 5 Filed Deo. 50, 1948 l l f /NVE/VTORS C. E. FAV D.A.$. HALE. 5:/ l C Y ATTORNEY Dec; 19, 1950 c, E. FAY ET AL 2,534,548

yHIGH-POWER WATER-COOLED ELECTRON DISCHARGEv DEVICE Filed Dec. 30, 1,9 48 4 Sheets-Sheet 4 /Nl/ENTORS C' E' FAV By D.A.$.HALE

A TTO/QNE V Fig. 5 is a sectional view of the filament platforms illustrating the method of mounting;

Fig. 6 is a sectional view of a portion of the terminal base plate illustrating the method of mounting the ilament vterminals and showing the mounting tool used;

Fig. '1 is a detail view of the grid showing the shield disc at the base of the winding;

Fig. 8 is a view mainly in section of another filament terminal; and

Fig. 9 is a sectional view of a base plate and terminal assembly illustrative of another embodiment of this invention'.

Referring to the drawing,` 4the cup-shaped anode |0, having a pumping tubulation 6 at its base, is connected to the terminal base plate which may be of Monel, through a metal cylinder |2, a metal flange I3, and a seal assembly. This assembly comprises the metal flanges |4, |5, metal cylindersl, |1'and aninsulating, e. g. glass, cylinder I8. The cylinders i6 and |1 may be of a nickel-iron-cobalt alloy metal known commercially as Kovarj `which readily seals to the glass cylinder I8 and has approximately the Same thermal coeflicient ofl expansion as the glass. By coating the Kovar with a thin layer f gold prior to sealing the glass to it, the radio frequencyresistance in thevKovar -"seal is cons iderablyy reduced so -that such a seal can be utilized where currentsof high density and high frequency are to be handled. AThe flanges I4 and I are preferably-ofv cold rolled steel and may be secured to vtheir respective cylinders I6 and I1 by copper brazing.

l The terminal base plate is provided with a plurality of. circularly placed countersunk apertures A2l through which extend the terminal assemblies 22. A central countersunk aperture 23 is also provided for a central cap 24. Each terminal assembly 22 comprises a lead 25 which is attached as by silver brazing to a metal cup 26 which is sealed to theglass cylinder 21. The glass cylinder 21 is in turn connected to the terminal base plate Hthrough a metal cylinder 28" 'in a manner to be described in detail later. "lead 25, the cup 26, and the cylinder 28 may all be The of copper. The central cap 24 comprises a glass dome 29 and a metal cylinder 30 which is attached in countersunk aperture -23 to the base plate in the same manner as the terminal assemblies 22.

The filament assembly includes three superfimposed apertured platforms best seen in Fig. 3.

The base platform closest to the terminal base iplate is an apertured cup 3| attached to the A .terminal vleads 25 -as by screws extending through apertures 32. A ring platform 33 is connected to .the cup 3| as by screws 34 through

appropriate apertures

35 and 36 toward the center of the cup and ring respectively.v The ring 33 supports a lplurality of hooks -31 with parallel drilled aper- .tures 38 at the end of each as best seen in Fig. 5.

A triangular platform 4| also supports a plurality of hooks 42 with parallel drilled apertures 43 at the end of each and is secured to the remaining three terminal leads 25A. The leads 25A are `slightly longer than the other terminal 25 to 'which the cup 3| is attached thereby providing insulating space between` Athe platforms. The leads 25Apass through clearing slots 45 in the ,cup 3| and are-thereby insulated from it. The

platform 4| is spacedfbetvveen the cup 32 and the ring 33 and is separated from them. The ,lhooks 42 pass through -clearing slots 44 in the 4 ring 33 and are slightly longer than the hooks 31 so that the two groups of hooks are in parallel alternate relation in a circular boundary as best seen in Fig. 5.

The compact platform assembly thus constructed provides a low inductance connection to the filament strands and an equalization oi the inductance to any one strand on one platform, because of the symmetry of the construction. Further the inductances to the indicated strands on both platforms are approximately equal because of the close positioning of the two platforms. The platforms themselves are also devoid of insulating material, the various parts of the assembly being separated by insulating space.

A sleeve member 5| extends through the apertured platforms 3|, 33 and 4| and is secured to the cup platform 3| as by screws 52 extending through

appropriate apertures

53 and 54 in a. flange 55 on the sleeve and in the cup respectively. The sleeve 5| thus extends through the platforms and the terminal base plate into the central cap 24. i

The filament strands 56 are attached at one end to the

hooks

31 and 42 in the parallel drilled

apertures

38 and 43 and may be secured by arc welding. At the other end, the strands 56 pass through the parallel drilled apertures 51, in the hooks 53 of a spider-shaped base support 53. The base support comprises a conducting ring 63 which forms a common connection for the lament strands and insulating members 64 which insulate the filament from a central standard or rod 65. Each of the lament strands therefore forms one-half of a series loop connected to the other half through the conducting ring 63. Series lloops are thus achieved without having to bend the strands which bendingor changing of the Strands from a single straight path might cause them to embrittle and break when subject to the temperature stresses produced in the device in operation. In the embodiment of the invention shown, there are eight loops of wire in parallel and thus eight positive and eight negative leads. The eight positive leads are connected to three of the terminals through one platform and the eight negative leads to the other three terminals through the other platform. Each Wire for the filament heating circuit is attached to the respective group of three alternate terminals so that one platform is one sidev of thel heating circuit and the other platform is the other side.

The central standard 65 may be composed of two separate parts 66 and 61 coupled together by a sleeve 68, this multiple construction providing a higher heat impedance. Or, alternatively, -the central rod may be a solid rod of molybdenum. A heat deilecting shield 1I is mounted on the standard 65 close to the hooks on the platforms. The standard extends slidably into the sleeve 5| through bearing rings 12 at both the top and the bottom of the sleeve. These bearing rings 12 allow the standard to slide endways during the heating and cooling of the filament. These bearings may be of sapphire, a material that has been 'found to provide a satisfactory bearing condition in vacuum and under heat. A shoe 13 is carried by the standard B5 at the end in the central cap 24 and has bearing yagainst it the free end of a helical spring 14`. The'other end of the spring 14 is anchored at 15 to the sleeve flange 55 through the platform cup 3|. The central standard 65 is thus kept'under compression, the yforce being applied through the standard to i the outer 'end or the aiment supportwhlch: is

which arefabricated: in suchV a manner thatI-a rib-8| extends the whole length ofiy the rod, as bestseen in Fig; '7. The rods 80 are arranged ina circle, the ribs pointing outward radially; and are attached, as by'arc welding, to a ring 82I which in turn isl securedl directly toe-terminall base plate ||-by screws-83. Onto-theseribs the'lateral wires 84 ofthe grid helixare-secured. The rods s 80;"the ring 02 andY the wires -94 -maybe of molybdenum. A shield 85, which mayI also be-' sheetV molybdenum, is provided to protect the seal between the metall cylinder |1 andthe glass cylinder |8 against electron bombardment from the' filament and hot filament leads. The restof the glass seal assembly isA shielded bythe reentrant anode I; The shield |35L is secured by f the screws that hold the grid itself in position. A grid shield86 is attached to the ends of the rods 80 adjacent to the spider-shaped base support 59 as by wel-ding and is provided with slots 81 into which the hooks 58 can extend.; the grid;

helix 84 is also bentoutwardly its last fewturns to clear the hooks, as bestseen in Fig. 2.

' Heating of the grid, andl the resultant thermionic emission of" electrons lfrom the grid, is

avoided because the improved structure aids in the dissipation of heat from the grid; The heating results Yfrorn bombardment of the grid rrby electrons and from heatradiated by the lament being absorbed by the'grid; The grid loses heat by radiation, mainly through the anode, and by conduction to its support, the terminal base plate by which the grid is directly supported. In the device disclosed, the loss/of heat through conduction is greatly increased,the rods 80serving not only to support the helix and to supply the radio frequency current, to the structure, but also to conduct heat from the grid to the ring 82v and the terminal plate H.. Radiation to the anode |0 may be .assisted by roughening the surfacel of the anode to,v reduce itsreectivity,

In the embodiment of they invention shown, the electron discharge device is water cooled'. Connecting cylinder 9| is attached to the cylin drical sectionv|2 and to an end nut member 92 which has a collar section 93 vattached as by soldering to a collar member 94.` A baffle 95 is attached as by soldering to the collary member 94- and extends between the anode I0 and the cylindrical-members I2 and9|. Waterentersby wayof the central port 96 in the collar section 93, goes up between the baflle 95 and the anode l0, then returns between the baille 95 andthe cylindrical membersv |12: andz 9| and exitsthrough a number of ports 91 in the nut 92. A screw thread 98 on the nut 92 provides a meansof securing the device to thewater system. s

In'the manuiactureof 'the device, a special tool |0|, shownin Fig. 6, isused forsecuringy the terminal assemblies 22 tothe terminal base plate v||. An internal thread |00 is provided in the metal cylinder 28, as best seen in-Fig. 6', andA is adapted to t the threaded end l-02-of the tool 0|. The` cylinder 28 is placed in the aperture My inthe base plate; andalconical washer-of solder Y'|03 is placed 'over the projecting sleeve |04 of the cylinder 28; The terminal leady 251er. 25A fits into a hollowed-out--portion |115A in the tool |0|. yA tapered nut |06- is pushed down over the tool |0| and a screw nut |01 isy run down to contact it, the upper end |08 of the tool |0| beingV threaded to engage the screw nut |01. The conicalsurface of the tapered nut |06 then; engages the sleeve portion |04. By holding the tool |-0| fixed and turning the screw nut |01 pressure is applied tov the sleeve portion |04. tending to open it bell-wise. The washer of solder` |03A is compressed in the space between the sleeveportion |04, now. belled out, and the countersinlr of the aperture2l. This operation is repeated for all the terminals, in this embodiment of the invention.v there are six, and forthecontrol cap 24, though there a separate tool'k is used ttinginside a larger diameter thread and not having' a hollowed-out portion, there being no lead to avoid..

Thev whole assembly is then brazed, the braz.- ing being done in a neutral or reducing atmosphere, using a high frequency coil to heat the plate up to the melting point of solder. An additional ring of solder wire is placed around each cylindrical portion 28 on the face opposite the countersink and serves to form a smooth llet at the point of jointure.

Thel usual procedure of winding the. lateral wires on the support rods and then welding them may result in an inaccurate out-of-round grid and the `making of one, weld may break those previously made. A special technique should be used whereby the lateral wire 8.4 isweldedateach support as itis wound; thus the prior welds areI- not affected. Grids made in this manner are veryA symmetrical and no trouble is experi enced with them due to weld collapsing.

In assembling the lament, each iilalnent strand 5,6 is rst passed through the aperture 38 orV 43 on the hook 3,1 or 42, respectively. Arc welding may be used for securing the strands, to the hook and they are welded one at a time. At the outer end, the strands pass through the aperturesl in the hooks 58. The strands are secured to these hooks-by placing a small amount of'solder, such as a mixture ofy cobalt and molyb' denum, nely divided and made into a paste, on each protruding wire` andsimultaneously heating all the hooks by high frequency coils, thereby melting theY solder and securing the filament strands; In this way, uniform and equal tension is assured in thelament strands.

Fig. 8 shows another-form of terminal assembly which may be used. The lead H3 and cap |4 aremade in one piece of cold rolled steel and are attached as by copper brazing to a cupshaped member ||5'of Kovan The edge |53 of the cup-shaped member ||5 is gold plated and then joined to glass cylinder seal |6. The other end of the glass cylinder seal ||6is similarly joined tol a cylindrical member ||1 of Kovar" which also has its edge |20 gold plated. The other edge of the member ||1 is joined to a shoe member ||8 which may be of cold rolled steel. Theterminal assembly is then attached to the terminalbase plate in the same manner as the previously described terminal assembly. However, before turning the screw nut |01 on the tool |0| to apply pressure to the sleeve portion |04 to open it up bell-wise, a number of'slots made endwise in the sleeve portion 10s to reduce the pressure needed. When using a copper sleeve portion, it will easily open without the aid of the slots. While-"Kovar"` may be used-for themetai portions of the seal because of its superior strength and the ease of making such a seal, the material is nevertheless of very high resistivity so that there is considerable loss where radio frequency currents iiow in the material and this loss can be great enough to cause the seal to develop excessive temperature. in order to reduce this effect, after annealing the seal portion', the Kovar can be plated with a material of lower resistivity such as copper. However, at the point where the glass welds the metal, the copper plating would be oxidized in the sealing operation. Therefore, it is necessary to use they gold plating there to provide the desired lower resistivity.-

As explained above the filament lead induct.-v ance in the embodiment of the invention shown in Figs.. 1 to 8 is low due to the plurality of leads arranged in a circle approximating solid sleeve. Fig. 9 shows another illustrative embodiment of a terminal base plate assembly according to this invention in which the filament leadl inductance is diminished even further by the use of Solid sleeve terminals. |The terminal base plate |22 is provided with a central aperture |23 through which extend the terminal cylinder iZflA and the terminal cap |25. The terminal |24 is attached to the terminal base plate |22 through metal cylinder |25, glass cylinder |21', metal cylinder |28, and metal connecting ring |23. Terminal |25 is in turn supported by the base plate |22 through the terminal |25; to which it is connected by metal ring |3I, glass ring l32, and metal ring |33. An apertured platform |34 is connected to the terminal |26 and an apertured platform |35 to terminal |25 through a connecting ring |36. Hooks l2 and 3l are connected to platforms |34 and |35, respectively. The sleeve 5| is carried by the connecting ring 13 and extends into terminal cap |25. The grid and filament structure are the same as with the plurality of terminals shown in the other embodiment. The terminal glass-to-metal seals may be Kovar seals of the type previously described.

While specific detailed constructions illustrative of this invention have been set i'orth'above, it is of course understood that various modifica-` tions may be incorporated in the device and the manner of assembly without departing from the scope and spirit of this invention.'

What is claimed is:

l. An electron discharge device comprising a terminal plate, a first electrode electrically attached to said plate, a plurality of terminals mounted on said plate and insulated therefrom, a plurality of apertured platforms supported by said terminals, each of said platforms being directly attached to said terminals at`a plurality of points, said points being on the circumference of circles formed by said terminals, a central standard extending through said platforms, attaching means supported by said standard, a second electrode comp-rising a plurality of strands supported between said platforms and said attaching means, and spring means tensioningr said filament strands.

2. An electron discharge device comprising a terminal plate, a plurality of terminals mounted on said plate and insulated therefrom, a plurality of apertured platforms secured to said terminals, each of said platforms being secured to said terminals at more than one point, said points being on the circumference of circles formed by said terminals, a connector comprising a conducting ring and hooks of conducting material attached to said ring, acentral standard attached to said connector and insulatedtherefrom and extending through said platforms.-

a plurality of filament strands connected to said hooks and said platforms, and a spring cooperat-vv ing with said standard for tensioning said fila-y ment strands.

3. An electron discharge device comprising av tioned within said boundary, a first apertured;

platform secured to certain of said terminals, a second apertured platform adjacent to but` separate from said first platform and secured. to certain other of said terminals, a sleeve carried by said second platform extending through the aperture therein, through the aperture in said first platform, and into said cap, a central standard projecting through said sleeve, a support. on the end of said standard, said support com-. prising a conducting ring insulated from said` standard and hooks of conducting material attached to said ring, a plurality of parallel filament strands connected to said hooks and said platforms, a helical grid surrounding said filament strands and electrically connected to said terminal plate, and a tension spring member surrounding said Isleeve and bearing against said standard.

4. An electron discharge device comprisinganl anode, a terminal plate, a terminal extending through said plate and insulated therefrom, a plurality of parallel filament strands within said device attached to said terminal, a ring attached to said plate, a plurality of rods extending from said ring, each of said rods having a longitudinal rib, and a grid attached to the ribs and extending along the length of said rods adjacent vsaid plate, said grid surrounding said filament strands. 5. An electron discharge device comprising a terminal plate, an anode, a plurality of terminals mounted on said plate and insulated therefrom, a plurality of apertured platforms secured to said terminals, a` central standard extending through said apertures, anchor means attached to said standard, a plurality of filament strands connected to said platforms and said anchor means, a ring attached to said plate, a plurality of rods extending from said ring, a grid attached to said rods and extending along Vthe entire length of said rods, said grid surrounding said filament strands, and a grid shield attached'to said rods adjacent said anchor means whereby said filament strands are entirely enclosed with-` in said grid and shield.

6. An electron discharge device in accordance with claim 5 wherein said rods each have a longitudinal rib and said grid is attached to the ribs.

'7. An electron discharge device in accordance with claim 5 wherein said anchor means comprises a rigid distributor spider and said grid shield is provided with peripheral cut-out portions intogwhich the arms of said spider fit.

8. An electron discharge device comprising a metallic terminal plate having terminals therein and insulated therefrom, a first apertured platform secured to certain of said terminals, a second apertured platform adjacent to but separate from said first platform and secured to certain other of said terminals, a plurality of hooks attached to each of said platforms, a sleeve carried ,by said second platform and lextending means through the aperture. therein and through the aperture-.in said first platform, a central standard )projecting through 'said sleeve, a rigid distribut'cr spiderf on the 'end" of said standard, said spider comprising a 'ring of conducting materialA and hooks of conducting vmaterial attached to said ring., aplurality of parallel filament strandsl connected to said spider hooks and said platform hooks, a ring attached to said plate, a plurality of rods extending from said ring, a grid helix attached to said rods and enclosing said strands, a grid shield attached to the end of said rods and having bifurcated portions therein into which the arms of said spider t, and a tension spring member surrounding said sleeve and bearing against said standard for tensioning said filament strands.

9.` In an electron discharge device, an apertured terminal base plate, said aperture being countersunk, and a hollow terminal assembly, said assembly comprising a first metallic cylinder member extending through said aperture, a glass cylindrical member attached to said first metallic cylindrical member, a second metallic cylindrical member attached to said glass member and a terminal lead attached to said second metallic cylindrical member and extending through said aperture into said device, said first metallic cylindrical member having an internal thread and a belled-out portion fitting into said countersunk aperture.

10. In an electron discharge device, a hollow terminal assembly in accordance with claim 9 in which said first metallic member comprises a steel shoe and a cylinder of a nickel-cobalt-iron alloy and said second metallic cylindrical member is of a nickel-cobalt-iron alloy and said lead is made of steel, said metallic members and said leads being copper plated and said metallic members being gold plated adjacent said glass cylindrical member.

1l. An electron discharge device comprising a metallic terminal plate having concentric terminal sleeve cylinders thereon, a first platform secured to one of said terminal sleeves, a second platform adjacent to but separate from said first platform and secured to another of said terminal sleeves, a sleeve portion carried by said second platform, a central standard projecting through said sleeve portion, a rigid spider distributor on the end of said standard, a plurality of parallel filament strands connected to said spider and said platform, a tension spring member surrounding said sleeve portion and bearing against said standard, a ring attached to said plate concentric with and of larger diameter than said terminal sleeve cylinders, a plurality of rods extending from said ring, and a grid helix attached to said rods extending along their entire length and encompassing said filament strands.

12. An electron discharge device comprising a metallic terminal plate having two concentric terminal cylinder sleeves therein, a first apertured platform secured to one of said terminal sleeves, a second apertured platform adjacent to but separate from said rst platform and secured to the other of said terminal sleeves, a sleeve por-v tion carried by said second platform extending through the aperture therein through the aperture in said first platform and into said concentric terminal sleeves, a central standard projecting through said sleeve portion, a rigid spider distributor on the end; of said standard, said Spider comprising a conducting ring insulated from said standard, and hooks of conductive matemi attached-tc saieringapiurality of paranei fllament. strands connected...to said hooks and saidplatforvrna a helical gridsurroundingfsald filament strands'and electrically connected. .to

3 said ter-minal plate, and' a tension springv 'meltii tral standard extending through said platforms,

attaching means supported by said standard, a plurality of filament strands supported between said platforms and said attaching means, spring means cooperating with said standard and one of said platforms for tensioning said lament strands, a ring of conducting material attached to said plate and concentric with and of larger radius than said circles, a plurality of rods extending from said ring, and a grid helix attached to said rods and extending along the length of said rods adjacent said plate, said grid helix encompassing said filament strands.

14. An electron discharge device comprising a metallic terminal plate, a plurality of terminals mounted on said plate and insulated therefrom, a pair of apertured platforms adjacent each other but separate from each other, mounted by said terminals. each of said platforms being directly attached to said terminals at a plurality of points, said points being on the circumferences of concentric circles formed by said terminals, a plurality of hooks attached to each of said platforms, a sleeve carried by one of said platforms and extending through the aperture therein and through the aperture in said other platform, a central standard projecting through said sleeve, a rigid distributor spider at one end of said standard and insulated therefrom, said spider comprising a ring of conducting material and hooks of conducting material attached to said ring, a plurality of parallel lament strands connected to said platform hooks and said spider hooks, a ring attached to said plate, a plurality of rods extending from said ring, a grid helix attached to said rods and enclosing said strands, a gridA shield attached to the end of said rods and having bifurcated portions therein into which the arms of said spider fit, and a tension spring member surrounding said Sleeve and bearing against said standard for tensioning said filament strands.

' CLIFFORD E. FAY.

DOUGLAS A. S. HALE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date .f 683,274 Hampson Sept. 24, 1901 310,431 Pfluger et al Jan. 23, 1906 1,124,504 Mueller Jan. l12, 1915 1,944,190 Mouromtseff Jan. 23, 1934 2,107,945 Hull et al Feb. 8, 1938 2,169,790 Cattoi Aug. 15, 1939 2,227,039 Smith et al. Dec. 31, 1940 (Other references on followingpage) Number UNITED STATES PATENTS Name Date 'Kellems Apr. 7, 1942 Chevigny Apr. 27, 1943 VCrawford Apr. 23, 1946 Dailey Apr. 15, 1947 Werner Jan. 13, 1948 Chevigny et a1 Apr. 6, 1948 Stevens Sept. 14, 1948 l2 FOREIGN PATENTS Number 4 4Ccmntry Date 103,252 Australia Feb. 24, 1938 OTHER REFERENCES Three New U1t1a-Hgh-Frequency Triodes, by K. C. Dewalt in Sept. 1941 issue of the Proceedings of the Institute of RadioEngneers, pp. 475 through 480.