US2408817A - Electron discharge apparatus - Google Patents

Description

Oct. 8, 1946.

D. L. SNOW ELECTRON DISCHARGE APPARATUS Filed Nov. 29, 1943 VENTOR vDon/m0 L. S/VoW 7 ATTORNEY Patented Oct. 8, 1946 ELECTRON DISCHARGE APPARATUS Donald L. Snow, Hempstead, N. Y., assignor to Sperry Gyroscope Company, Inc., a corporation of New York Application November 29, 1943, Serial No. 512,222

9 Claims. 1

This invention relates to electron discharge apparatus and is particularly concerned with improvements in electron discharge apparatus of the hollow resonator type and methods of making the same.

Hollow resonator devices wherein an electron beam is passed in energy exchanging relation with the resonator field are known in various structural embodiments. The present invention represents mainly improvements in structure and assembly over such earlier devices, for providing an efficiently organized and operating combination of correlated parts.

It is, therefore, a major object of the invention to provide electron discharge apparatus of the hollow resonator type having novel construction and compact efficient arrangement of its component parts.

A further object of the invention is to provide electron discharge apparatus of the hollow resonator type wherein the parts producing and acting on the electron-stream are aligned in a novel manner.

A further object of the invention is to provide a novel unitary sub-assembly for a hollow resonator electron discharge device, wherein a cathode, a hollow resonator and an electronic reflector are novelly mounted in predetermined relation; and to provide a novel method of assembling the same.

A further object of the invention is to provide a novel compact sub-assembly wherein the parts of a hollow resonator device eifective upon the electron stream are permanently associated in a unitary mounting.

A further object of the invention is to provide hollow resonator apparatus arranged within an envelope and embodying novel thermally respon sive frequency control structure associated with the resonator.

Further objects of the invention will presently appear as the description proceeds in connection with the appended claims and the annexed drawing, wherein:

Fig. l is an elevation, partly in section along line l-l of Fig. 3, of a hollow resonator type electron discharge device according to a preferred embodiment of the invention;

Fig. 2 is an elevation, partly in section, of the device of Fig. 1 but as viewed at an angle of about ninety degrees from the direction viewed in Fig. 1;

Fig. 3 is a section along line 33 of Fig. 1 providing a top view of the cathode, resonator, reflector unit in the assembly;

Fig. 4 is a fragmentary elevation of a sub-assembly including a somewhat different resonator arrangement than that of Figs. 1-3; and

Fig. 5 is a substantially perspective View illus trating details of the cathode, resonator, reflector sub-assembly unit of Fig. l, and manner of making the same.

Referring first to Figs. 13, the assembled high frequency device of the invention comprises a cylindrical metal envelope l I and a base assembly [2. Base l2 has a bottom wall l3 made of some moldable insulation material such as a phenolic condensation product, and an upstanding metal collar 14 is secured to wall l3.

Envelope H and collar l4 are formed with integral radial flanges I5 and I6 which extend in coextensive contact with opposite sides of a relatively rigid metal plate I1. Preferably flanges l5 and 16 are permanently secured, as by welding or soldering, to plate IT. The seal between flange l5 and plate I! is preferably vacuum tight so as to maintain a vacuum within envelope H. The seal between flange l6 and plate I! is preferably at least air tight to keep out dust and moisture.

A suitable thick stifiening plate 3 is secured as by welding to the upper surface of plate I1 so as to be disposed within envelope II. If desired, plate l8 may be integral with plate l1. Any desired number of sealed conductor mounts, for the device of Fig. 1, preferably five, are carried by plate l8. Some of these conductor mounts are indicated at l9 and 2l2 l.

Mount l9 comprises a short thin metal tube 25 extendin through suitable apertures in plates I1 and IS with its upper end flanged over the top surface of plate l8 as at 28. Tube 25 is suitably welded or similarly secured to plate l8 so as to provide a vacuum tight connection therewith. A short rigid conductor rod 21 imbedded in a glass or like insulating seal 28 axially within tube 25 has its upper end disposed within envelope II and its lower end suitably fastened to a hollow metal prong 29 rigidly supported on insulation wall l3 of the base.

Each of mounts 2l-24 are of substantially identical structure with mount l9. As for those specifically illustrated, mount 2| supports a conductor rod 3| fastened to prong 32, mount 23 supports a conductor rod 33 fastened to prong 34, and mount 24 supports a conductor rod 35 fastened to prong 36. Thus all the conductors necessary for introducing required electrical energy for operation of the elements within envelope l i enter the envelope through vacuum tight insulatiOl'l seals.

Plates i! and iii are centrally apertured for mounting a thin malleable exhaust tube 31 which has its upper end sealed vacuum tight to plate l8 and is pinched off and closed at its lower end at 38 to complete sealin of envelope ll after exhaust. Wall I3 is formed with a suitable molded depression 39 for accommodating exhaust tube 31.

All of the elements for producing and directly acting upon an electron beam within envelope l I are preferably preassembled, prior to mounting in the device, in a permanent sub-assembly in which proper alignment is obtained and maintained as will later be explained.

The sub-assembly comprises a cathode or electron emitter unit 4| for producing an electron stream, an electron stream focusing or modulating electrode 42 surrounding the stream, a cylindrical hollow resonator unit 43 through which the electron stream is passed, and a reflector unit 44 for repelling and returning electrons of the stream into resonator unit 43.

Resonator 43 has its bottom wall fixedly mounted as by soldering within a suitable aperture in a rigid metal platform 45 extending parallel to plate l8. As shown in Fig. 1, resonator 43 is formed with a flexible annular top wall portion 46 surrounding a relatively rigid central region 41 which is centrally apertured at 48. Aperture 48 is aligned with a similar apeiture 49 at the upper end of a reentrant conical hollow pole integral with the resonator bottom wall. Wall portion 46 of the resonator is preferably an nnularly crimped metal member which may be secured to or integral with the resonator side walls.

The circumference of platform 45 is formed with three equally spaced edge notches or recesses 52 permitting free passage of three parallel equally circumferentially spaced longitudinal support rods 53. Rods 53 are parallel to the longitudinal axis of the device and are made of insulating material. Preferably, rods 53 are bodies of glass or some other hardenable thermoplastic substance as will appear.

Glass rods 53 are rigidly and permanently mounted in parallel relation by means of three equally spaced stiff radial wires 54 which have their bent inner ends fixed by welding or soldering to platform 45 and have their outer ends imbedded. within associated rods 53.

Cathode unit 4| is rigidly and permanently mounted in alignment with apertures 48, 49 by means of three equally spaced stiff radial wires 55 which have their inner ends fixed by welding or soldering to a flange 56 on the cathode unit and have their outer ends imbedded within associated glass rods 53.

Focusing electrode 42 is rigidly andpermanently mounted in alignment with cathode 4| by means of three equally spaced stiff radial wires 51 which have their inner ends fixed by welding or soldering to electrode 42 and have their outer ends imbedded within associated glass rods 53.

Reflector unit 44 comprises a metal block having its lower reflecting surface 58 aligned with resonator aperture 48, and reflector unit 44 is rigidly and permanently mounted to so align surface 58 with the electron stream by means of three equally spaced stiff radial wires 59 which have their inner ends fixed by soldering or welding to reflector block 44 and have their outer ends imbedded within associated glass rods 53.

Fig. 2 illustrates the manner in which platform 45 is rigidly supported upon plate IS. A plurality of circumferentially spaced short posts 6! are formed at their lower ends with threaded extensions 62 interfitting with suitable tapped holes in plate IS. The upper end of each post 6| is formed with a reduced threaded extension 63 which extends freely through an aperture 64 in platform 45 within a tapped central bore 65 in the lower end of an elongated post 66. Any suitable number of posts 6| and 66 may be thus provided although only two are illustrated. Posts 6| may first be mounted rigid with plate l8. Platform 45 is then seated upon the tops of posts 6|, with extensions 63 projecting therethrough, and posts 66 are then mounted nut-like on extensions 63 to securely clamp platform 45 between the posts.

The upper ends of posts 66 are formed with reduced threaded extensions 61 which project freely upward through suitable apertures in a rigid bridge 68 generally parallel to platform 45. Bridge 68 is securely fastened to posts 66 as by nuts 69.

Plate l8, platform 45, bridge 68 and posts 6! and 66 thereby provide a strong rigid frame for supporting the elements of the device within envelope II, and for withstanding strains incident to operation of the frequency control mechanism to be described.

Bridge 68 is formed with a large aperture ll axially of the device. A plate 12 of electrical insulating material is securely mounted over aperture H by a sheet metal rim strip 13 which is welded or similarly fastened to bridge 68.

Plate 12 is also centrally apertured for mounting thereupon a shouldered metal terminal block 14 formed with a central bore into which extends the upper end of a relatively rigid electrically conductive strut or rod 15 of Duralumin or some other metal or alloy having a high coefficient of thermal expanison. Strut 15 is secured against axial movement within block 14, as by screw I6. Block 14 in turn is secured against displacement relative to plate 12, as by its illustrated interfitting engagement with the aperture in plate 12, and by peening or otherwise flanging its lower end at I1 over the adjacent lower surface of plate The lower end of strut 15 extends through the base of an inverted U-shaped bracket 18, and a suitable fastening element 19 anchors strut 15 to bracket 18. The opposite downwardly extending legs of bracket 18 are formed with shouldered terminals 8| inter-fitting with the upper ends of the corresponding upstanding legs of second U-shaped bracket 82. The bas of bracket 82 is apertured and formed with an integral downwardly extending hollow boss 83 which is rigidly secured, as by soldering, to the resonator wall region 41 about exit aperture 48.

Strut l5is coaxial with resonator 43 and located on the longitudinal centerline of the device. The purpose of the above described shape of brackets 78 and 62 is to obtain a solid connection between the lower end of strut 15 and the resonator wall region 41 without disturbing reflector unit 44 which is also located axially on that centerline. Reflector unit 44 extends within boss 83 for proper location relative to resonator aperture 48, but the parts are so dimensioned as to prevent contact between reflector 44 and bracket 82 during all conditions of operation.

Strut T5 is energized by current passing therethrough. Conductor rod 33 is welded or soldered to the lower end of a relatively stiff conductor 84 which has its radially bent upper end soldered or welded to block 14. A loose glass or like insulating sleeve 85 supported by conductor 84 insulates it electrically against the electrically grounded frame parts such as platform 45. The lower end of strut l5 completes an electric circuit by grounding on the frame.

Cathode unit 4| is energized chiefly by a lead 86 from conductor rod 21, and a lead 81 supporting a glass insulating sleeve 88 is welded or soldered at opposite ends to conductor rod 3| and a conductor 89 rigid with reflector block 44. Other elements within envelope l I are similarly suitably energized.

Ultra high frequency energy, in the neighborhood of 3x10 cycles per second and higher, is extracted from resonator 43 by means of a concentric transmission line section having a hollow outer conductor 9! and a coaxial inner conductor 92 supported and sealed therein by insulating beads of glass or polystyrene in a known manner. Outer conductor 9| passes through suitable apertures in plates ll, 18 and base wall l3. A short metal collar 93 upstanding from plate l8 surrounds outer conductor 9! and this joint is vacuum sealed to maintain the interior of envelope ll vacuum tight.

As illustrated in Fig. 1, a conductive loop 94 interconnects the line conductors at their inner ends and projects through a suitable aperture in the bottom wall of resonator 43 for coupling with the ultra high frequency field within the resonator. The projecting lower end of the transmission line is externally available for connection to any utilization apparatus.

Figs. 4 and 5 illustrate an embodiment of the invention wherein a different type of resonator is mounted on platform 45. Here a relatively small diameter cylindrical resonator 95 has its bottom wall fixed as by soldering in a suitable central aperture in platform 45. The bottom wall of resonator 95 is formed with a hollow reentrant pole 96 having an aperture 91 aligned with a similar aperture 98 in the upper resonator wall 99. A bracket 82 is secured, as in Fig. 1, to the upper resonator wall about the exit aperture.

As illustrated in Fig. 4, the upper and side walls of resonator 95 are radially extended for an appreciable distance, and circumferentially joined. The purpose of this construction is to provide an upper resonator wall of suflicient area to safely provide adequate flexibility when the spacing between apertures 91 and 98 is varied during resonator tuning. Since this specific reso-. nator structure is not part of the present invention, further description is unnecessary.

In the embodiment of Figs. 4 and 5, platform 45 is secured to glass rods 53 by three equally spaced stiff radial wires l8! which have their outer ends imbedded in rods 53 and are soldered or welded along the bottom surface of platform 45 as illustrated. The cathode, focusing electrode and reflector are secured in the sub-assembly exactly as in Figs. 1-3.

In operation, in both embodiments of the invention, a stream of electrons is projected by cathode 4| through resonator 43 (or 95) and is returned into the resonator by reflector 44 which is maintained at a suitable potential. The electron stream excites and maintains a high frequency field within resonator 43. Accepted theories of electron velocity modulation of the stream by interaction with the field to obtain this operation in such devices are explained in United States Letters Patent No. 2,250,511 to which reference is made for further detail.

Also in both embodiments, frequency control is accomplished by regulation of the temperature of strut 15. Since strut 15 is anchored at its upper end to the rigid .element supporting frame and connected at its lower end to the flexible resonator upper wall portion, elongation or contraction of strut 15 in response to temperature changes caused by variation of the electric current passed therealong results in displacement of aperture 48 respectively toward or away from aperture 49, thereby respectively proportionately decreasing or increasing the frequency of resonator 43. Control of the current passing along strut I5 is of course obtained by adjustment of a suitable external variable power source (not shown).

A very important feature of my invention is the sub-assembly of parts which produce or act directly on the electron stream. This is of particular importance where the resonator is small and has small electron permeable regions or apertures, as where ultra high frequencies are contemplated. Difliculty has been experienced during assembly of such devices in obtaining proper and reliable alignment of the cathode, resonator and reflector. I

The present invention overcomes the above difficulties. As illustrated, the various elements of the sub-assembly comprising cathode unit 4|, focusing electrode 42, platform 45 with the resonator (43 or secured thereupon and refiector unit 44 are all mounted in desired alignment and related position by suitable jigs or fixtures designated at I82. Preferably bracket 82 is fixed to the resonator upper wall prior to this operation, which is of course performed only after the various sets of stiff radial wires above described have been soldered or welded to the elements.

Jigs or fixtures I02 are so designed that the free ends of the stiff radial wires are free, so that glass rods 53, heated until suitably plastic, may be forced onto the wires to imbed the ends of the latter therein. Rods 53 are allowed to remain impaled on the wire ends until cooled. When cooled, rods 53 become hard and rigid permanent insulation support and spacer members which maintain the elements in exactly the relation they were preset by jigs I02. No further alignment or adjustment operations are needed, and the whole assembly may be incorporated into the device by mounting platform 45 on posts GI and making the necessary electrical connections.

If desired, apertures 48, 49 or 91, 98 may be provided with suitable wire mesh or like grids, although such are not essential where the apertures are small.

The above described construction provides a sturdy, compact hollow resonator device wherein the resonator and control elements are all mounted upon a strong rigid frame within the envelope, and which is assembled with a minimum of effort. The arrangements for precisely and permanently aligning the various elements producing or directly acting on the electron beam is especially important for hollow resonator devices embodying resonators of small volume and electron permeable areas of small size.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. High frequency electron discharge apparatus comprising a support, a platform carried by said support,a hollow resonator mountedon said platform, a rigid body of electrical insulating material secured to said platform and electron emitter and deflecting electrode assemblies secured to said body and disposed on opposite sides of said resonator in alignment therewith.

2. The apparatus defined in claim 1, including an electron stream control electrode adjacent said emitter assembly also secured to said body.

3. High frequency apparatus comprising a platform, a hollow resonator mounted on said platform and having electron permeabl regions, a plurality of laterally extending supports secured to said platform, a cathode mounted at one side of said resonator for supplying a stream of electrons for passage through said regions, a plurality of laterally extending supports secured to said cathode, an electrode mounted at the other side of said resonator for reflecting said electron stream into said resonator, a plurality of laterally extending supports secured to said reflector electrode, and a plurality of rigid electrical insulating bodies peripherally spaced about said platform and secured to said lateral supports and fixedly maintaining said cathode, resonator and reflector electrode in desired alignment.

4. The apparatus defined in claim 3, including a. focusing electrod adjacent said cathode for controlling said electron stream, and a plurality of laterally extending supports secured to said focusing electrode and to said rigid bodies.

5. High frequency apparatus comprising an electron emitter assembly, a hollow resonator assembly and an electron repelling electrode assembly all mounted in predetermined alignment, a plurality of circumferentially spaced bodies of rigid electrical insulating material, and lateral supports projecting from said assemblies and secured to said bodies and individually attaching said assemblies to said bodies.

6. High frequency electron discharge apparatus comprising a base, a frame rigid with said base, a

support on said frame, and means carried by said support substantially permanently mounting a cathode assembly, a hollow resonator assembly and a reflector assembly in alignment.

'7. High frequency apparatus comprising a support, a hollow resonator having a portion movabl for varying the frequency of said resonator mounted on said support, a cathode structure mounted on said support in alignment with said resonator, a frame structure secured to said support, and a thermally responsive frequency control member having a rigid electrically insulated connection to said frame at one end and a rigid connection to said movable portion at its other end.

8. High frequency apparatus comprising a base, an envelope rigid with said base, a plurality of posts upstanding from said base within said envelope, a support mounted on said posts, a hollow resonator mounted on said support, a cathode structure mounted on said support in alignment with said resonator, a bridge extending across the ends of said posts remote from said base, an electrical insulating member fixed to said bridge, and an electrically conductive frequency control member secured at opposite ends to said insulating member and said resonator.

9. High frequency apparatus comprising a base, an envelope enclosing a space adjacent said base, a plurality of post members projecting from said base into said space, a support mounted on said post members, a hollow resonator having electron permeable regions mounted on said support, means fixed to said support for producing an electron stream for passage through said regions, a bridge extending across th ends of said post members remote from said base, an electrical insulating member fixed to said bridge, and an electrically conductive frequency control rod secured at opposite ends to said insulating member and said resonator.

DONALD L. SNOW.

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