US2945159A - Magnetron device - Google Patents

Description

2 Sheets-Sheet 1 INVENTOR.

MAGNETRON DEVICE July 12, 1960 R. M. scANzANl Filed March 25, 1957 ROBERT M. SCANZ AN July 12, 1960 R. M. scANzANl MAGNETRON DEVICE 2 Shee'ts-'Sheeifl 2 Filed March 25, 1957 INVENToR.

IZOBEIZT M. SCANZAN\ AT1-02N EY MAGNETRON DEVICE Robert M. Scanzani, Beverly, Mass., assgnor to Bomac Laboratories Inc., Beverly, Mass., a corporation of Massachusetts Filed Mar. 25, .1957, Ser. No. 648,240

2 Claims. (Cl. SI5-B951) The present invention relates generally to electron discharge `devices of the magnetron type and Aspecically, to novel structure for positioning and adjusting the cathode electrode.

Magnetrons primarily comprise'a multicavity anode electrode with a cathode electrode concentrically disposed therein. In the manufacture of such devices the positioning of the cathode is extremely critical and the tolerances allowed are very small. Packaged magnetrons provide a cathode structure which extends axially through a component of the magnetic circuit forming a part of the envelope and is supported at a distance from the anode-cathode interaction space. (Following assembly of the cathode component to the tube envelope, further adjustment is impossible. Hence careful control with appropriate jigging is necessary to assure accurate alignment.

The present invention, therefore, has for its principal object the provision of a novel cathode positioning and adjusting mechanism Ifor magnetrons to facilitate alteration of anode-cathode spacings in a finished tube.

Another object is to provide a novel electrode positioning and adjusting mechanism for magnetrons which permits both lateral and axial displacement of the cathode in a finished tube.

'I'he objects enumerated are attained vby means of a housing member surrounding the cathode assembly supporting structure. A bearing race member is positioned within the housing yand threadably engages the cathode electrode tubular extension. A plurality of hall bearings are spaced within the housing member and engage the bearing race member. Threaded studs having a tapered center portion are positioned Within hubs circumferentially `disposed around the housing member with the tapered portion engaging the ball bearings. Ax-ial movement of the studs will result in lateral displacement of the cathode electrode. Further, rotation of the bearing race member will result in axial displacement of the electrode. A diaphragm member cooperates with the cathode support structure to permit axial movement without loss of the vacuum condition of the tube.

Other objects, features land advantages will ibecome apparent after consideration of the following detailed specification and the appended drawings, in which:

Fig. 1 is a perspective view partly in section of the ernbodiment;

Fig. 2 is a view-taken along the line 2-2 in IFig. 1;l

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l2,945,159 latented July 12, 1960 ice rial form with a body member 3 the envelope of the embodiment. Tubular member 4 secured to pole piece 1 provides means for evacuation of the envelope and a dielectric tip-olf seal 5 encloses the end thereof to preserve the vacuum condition. Iln a tunable magnetron member 4 would be utilized to position the tuning mechanism and a separate tubulation could be provided for evacuation. Multicavity anode 6 having a central opening therethrough is positioned within cylinder 3, as shown. The output coupling means 7 may be secured to the outer surface of cylinder 3 and communicates with a slot 35 in the multicavity anode 6.

A support cylinder 8 is sealed to the wall of recess 9 in the outer face of pole piece 2. In the method of assembling the embodiment the envelope comprising pole pieces 1 and 2 and cylinder 3 together with member 4 and cylinder 8 may be fabricated as a separate sub-assembly. This prevents contamination of the electrodes during the metal brazing or welding process. The overall cathode structure together with the positioning and adjusting mechanism of the invention may be completely subassembled and then joined to the cylinder 8 by means of a glass seal 10 to complete the tube prior to exhaustt Cathode electrode 1-1 concentrically positioned within the central opening in anode 6 is mounted upon an elongated hollow tubular extension 12 which extends axially through the passageway defined in pole piece 2. A heat radiator 13 may be provided adjacent to the cathode and this component extends partly into pole piece `r1. VThe cathode 11 may be of the indirectly heated type with the heater concentrically disposed within the cathode and a conductor `14 axially ldisposed within extension 12. Conductor 14 is supported by a dielectric insulator 15 and the outer end 16 is connected to the heater supply. The adjusting mechanism is shown generally at 17 and is secured to sleeve 18 which is in turn joined by glass seal 10 to cylinder V8. Y c

Referring now to lFigs. 2, 3 and 4 the teachings ofthe present Vinvention will be described. Cylindrical housing member 19 having a central opening is provided with a shoulder 20 to which sleeve 18 is secured. Aplurality of hub. portions '21 are spaced around the outer surface thereof with each hub havin-g a passageway V22 extending parallel to the axis of the tubular extension 12. Another passageway 23 perpendicular to the tube axis is also provided. Passageway -22 is threaded as at 24 at one end to receive the threaded portion 25 of adjusting stud 26. The center portion 27 of stud 26 is tapered as shown and bears against ball bearing 28 which is inserted through passageway 23 prior to the introduction of the stud in the hub passageway 22.

`Coaxially disposed within housing member 19 and secured to cathode tubular extension 12 as shown is a sleeve 29 having a threaded outer surface 30. Bearing race member 31 is threaded on sleeve 29 and is provided with slots 32 to receive a tool for rotation of member 31. A groove 33 provides means for engaging the =ball bearings 28.

Diaphragm 34 of a metal such as Monel is secured between the inner end of member '19 and tubular extension 12 to retain the vacuum condition of the tube as the cathode is positioned or adjusted in the manner now to be described.

After assembly of the magnetron device including mounting of the cathode sub-assembly and completion of seal 10, the exhausting and tip-ott process steps are periformed. The device is then electrically tested and the cathode may be adjusted for maximum eiciency. The lateral adjustment yis provided by means of axial movement of studs 26 Within hubs 21. 'Ihe movement of tapered portion 27 results in displacement of bearings 28 to thereby adjust the cathode laterally. Another precision adjustment is provided -by the invention in-thatmember-lnllmayV be rotated by insertion of asu-itable tool such as a-spanner wrench inholes V32,. Since bearings-@Safe positionedY within- `groove 33 and are' locked Within^ passagevvay 23 movement of member 31 results in axial: displacement of the'cathode. Y

j There is; thus disclosed at simple and -eicient vpositioning and adjusting mechanism whichpermits very precise adjustmentof anode-cathode spacings inmagnetron devicesafter assembly at the production-tacilityt Further, after operation when changes in performance may occur it is possible, by adjustment-of thecathode, to bring many of these devices within the-realmo-f operativev tubes when prior art tubes would normally be replaced.l Neither of these advantages may be found in existing magnetron devises.

What is' claimed is :g

l. A magnetron tube comprising aV mult-icavity anode member having a central opening, magnetic pole pieces positioned at opposite ends of said anode member, cathode supporting meanssecured to one of said pole pieces, acathode electrode extending axially through said pole piece and supporting means With its inner end concentrically positioned within said central opening, means forl positioningl and adjusting said cathode Yelectrode vmounted on Ysaid supporting means, said `adjustingmeans compris'- ing--a cylindrical housing member having aY plurality of radial hubs circumferentially disposed thereon, `each hub having an axially movable threaded stud having a tapered intermediate portion, a rotatable member threada-bly secured to said cathode electrode in the regionl adjacent to said cylindrical housing member, `a plurality of ball bearing members positioned within said cylindrical housing incontact with said rotatable member and the tapered portion of each of said threaded studs, said cathode electrode being displaced axially by rotation of said rotatable member and laterally by axial movement of said threaded studs.

2. A- magnetronk tube comprising a multicavity anode member having a central opening, magnetic pole pieces positioned -at opposite ends of said anode member, at least one of said pole pieces having an axial passageway, a support cylinder secured to the outer face of said pole piece, a cathode electrode having a tubular extension extending through said axial passageway with its inner end concentrically disposed within said anode central opening, cathode supporting structure insulatingly sealed to said support cylinder, means for 'adjusting'and positioning said cathode electrode mounted on said cathode supporting structure, said means comprising a cylindrical housing member having a plurality 'of hub portions along the outer peripheral Wall, each hub portion housing a threaded stud positioned to move parallelto the tube axis, said threaded studs having a tapered non-threaded intermediate portion, a sleeve secured" to said cathode electrode tubular extension in the region adjacent to said housing member, a bearing race member threadably secured to said sleeve, `an annularV groove'. defined along the outer peripheral'wall of'saidbearing race member, a'ball'bearingmember positionedwithin*eachhub portion in contact withy said tapered portion of said studs and said bearing member groove, said cathode electrode being displaced axially fby rotationV 'of said bearing race member and laterally by axialmovement of said threaded studs;

References cited in the fue ofth'is patent UNITED 'STATES P'rfinrrrsV

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