US2444419A - Magnetron - Google Patents

Description

July 6, 1948.

R. J. BONDLEY MAGNETRON Filed Dec. 24, 1942 Q r I Inventor- Ralph J. Bondley,

y His Attofney Patented July 6, 1948 MAGNETRON Ralph J. Bondley, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application December 24, 1942. Serial No. 470,040 4 Claims. (01. 250-275) My invention relates to ultra high frequency electric discharge devices and more particularly to ultra high frequency electric discharge devices of the magnetron type.

With the ever increasing demand for higher frequencies and because of the desirability of using discharge devices of the magnetron type for this purpose, there has been evidenced a decided need for simplified electrode structure which permits facility in factory production and which affords improvements in the operating characteristics of devices of this type. In accordance with the teachings of my invention described hereinafter, I provide a new and improved structure for an ultra high frequency magnetron wherein the anode structure is of simple construction and arrangement and whereby the electrical operating characteristics of the magnetron are substantially improved.

It is an object of my invention to provide a new and improved ultra high frequency electric discharge device.

It is another object of my invention to provide a new and improved ultra high frequency magnetron.

It is a further object of my invention to provide new and improved anode structure for an ultra high frequency magnetron.

It is a still further object of my invention to provide a new and improved anode structure for an ultra high frequency magnetron which defines a plurality of space resonant regions or cavities, and in which the various space resoonant regions are effectively coupled by using a simple arrangement of parts.

Briefly stated, in the illustrated embodiment of my invention I provide an ultra high frequency magnetron comprising a centrally located cathode, which may be of the thermionic type, substantially surrounded by an annular anode structure. The anode structure comprises an annular metallic member or ring which supports a plurality of circumferentially spaced inwardly extending or radial vanes which may be positioned at one extremity in slots provided by the ring. The vanes have a substantially uniform thickness and are of such number and thickness relative to the diameter of the supporting ring to produce an effective concentration, at their inner extremities, of the electric component of the electromagnetic oscillations in the various space resonant regions defined by adjacent vanes, so that there is an effective interchange of energy between the space resonant regions and the oscillating or gyrating electric discharge or space charge of the device. More particularly, the thickness of the vanes is preferably equal to or greater than the distance between adjacent vanes at the ends facingthe cathode so that the electric component of the both, of the radial vanes, and preferably in the plane of the top or bottom of the annular anode structure.

For a better understanding of my invention,

. reference may be had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. Fig. 1 illustrates an embodimentof my invention as applied toan ultra high frequency magnetron construction of thetype disclosed and broadly claimed in a copending patent application Serial No. 447,903, of Elmer D. McArthur, filed June 22, 1942, and which is assigned to the assignee of the present application and is now United States Patent No. 2,412,824, issued December 17, 1946. Fig, 2 is a plan view of the anode structure.

Referring now to Fig. 1 of the accompanying drawing, my invention is there illustrated as applied to an ultra high frequency magnetron including an elongated cylindrical container, the

lateral wall of which is provided by a single me-.- tallic tube I which consists of aferromagnetic material such as cold rolled steel, or the like. The ends of the container or tube l are closed by flanged members 2 and 3 which are welded or otherwise hermetically joined to the inner surface of tube I.

Within the container and approximately at its central region I provide an anode structure 4, which is shown in plan view in Fig. 2 and which comprises a metallic annular member or ring 5 preferably constructed of copper or brass and which is provided with a plurality of annularly spaced. slots 6 into which are fitted inwardly extending radial-type vanes 'la'lh inclusive, thereby defining a plurality of space resonant regions or cavities which are energized by an oscillating or gyrating space charge established between the ends of the radial vanes and a cathode structure to be described presently.

The diameter of the ring 5, the number of radial vanes and the thickness thereof are preferably chosen so that. the thickness of the vanes is equalf to or: greaterthan the distance between the inner extremities of the vanes facing,-or immediately opposite, the cathode structure. More particularly, referring to Fig. 2, the distance t; is preferably greater than the distance d. g

In order to establish a magnetic field, I employ magnetic means which may-comprise a'pair of permanently magnetized magnetic pole pieces 8 and 9 spaced longitudinally along the axis of the discharge device, and.-.which are respectively seated upon metallic disks Ill and II of ferromagnetic material and which in turn areprovided with radially extendin passages I2 and I3 :tofiacilitate: extraction. of air or gas during the evacuation process. 'Passage l3 and the'entire --deviceafter exhaust maybe sealed? bywmeans'of i atmetallic tubulation- Id. attached to the flanged member 3.

The :anode structure: may be "-firinly ,positioned tbyizmeans' of .a.pair of. annular spacing members 1 l5r'1and l E which abut' the ring 5 :andwhich also aarein engagement-with apairof transverse sup porting disks. lltland l8 which engage suitably formed shoulders provided .by magnetic pole pieces 8 and 9. Supporting rings l9 and .adapte'dt'to'-be slippedover the pole pieces 8 and 9, 'respectively, may be welded or soldered to these members'andbasefdisks l0 and II.

'There'.is"provided centrally within the anode t s-tnuc-ture 'ila cathode, such :as a r thermionic cathodegiwhichamay. include :a efiangedt metallic icylirideriZLiLpreferabIy constructedof nickel or molybdenum, and Which;'is1 coated with: .an electron emissive material such as barium oxide. i'llhere :is also provided a'filamentaryncathode "heating element'i22--.'within cylinder'll. Theends 'ofxicylind'erfl l iarerclosedi lby; means' of..:.apertured :Itdisks 23: and 24 to receive cathode-supporting "structure, and. connecting means. for supplying energizing current to the-heating element:22.

E'Ihe cathode structure may besupported'by smeans .aof a concentric cathode construction l2WhlCh extends-J through longitudinal channels: 25

aandilfi infimagn'etic polepiecesell and'9;. respec- --tively. Referring -'t0'l the concentric: cable con- 'struction,:therevis provided a tubular metallic miterconductor. 21, -.an..:inner conductorfi-ZB Hand an interspaced tubular :insulatori:29. Externally aaccessible'" terminals fOI COHdUCtOIS- ZY and 28 -'are provided..-by lead-in wires 3!). and 3 I x which are; anchored inta g1ass.;bead-or -sea1 32. -The =.-!:seal"32-:may:. be supported by a flangedfmetallic cylinder- 33 which '15 welded or soldered: to mem- 'bep Z and'-isa1so,-of course, insealed engagement 'with seal 3 2 As a means for centering and .positioningai'the concentric cathode construction,- I' employwith- 'in thevicinity-of the po'le face of pole pieces 8 an insulator 34 which firmly engages outer: conductor il and which is also'in'cngagement with -"'the- -wall-of channel 25. LInsulator 34 maybepo- 'sition'ed longitudinally within :channel 525 ii-by means of acopper tube- '35 whichabuts v the=upper endof in'sulator :34. 'At the lower sextremr'ity; the cathode structure rmayi-becsupported and "centered by means of an 5 additional insulator 36 within channel 26,. and. is sprovldedcwith-z-ait centering: pin" 31 which extends through: there aperture in disk 24 and is turned over, thereb forming a firm lower support for the cathode.

It will be noted that the upper terminal of the cathode heatin element 22 is connected to the 5 inner conductor 28, and that the lower terminal is connected to the disk 24, thereby completing the energizing circuit for the heating elenmentzthrough cjzlinderZl, fdi'Sk 23and outer con- -ductor Z'l.

Certain features of the concentric cathode "construction and the insulating support therefor .are: disclosed and claimed in my copending patent application Serial No. 465,424, filed November 13, :1942 and now United States Patent No. 2,406,277, issued August 20, 1946, and in a copending patentapplication of George M. White, Serial.No..465. l-01,. also filed November 13, 1942 and now United States Patent No. 2,406,276, issued- Augr1st 20, 1946, both of which are assigned to the assignee of the; .present application.

'Asra'means for extracting high frequency encrgy'from the various space-resonant'regions, suitable output electrode means are provided which may take the'form ofa: loop 38comprising anextension of an inner conductor 39 constiltutingapart of a concentric transmission-line including conductor and an outer tubular conductor 40.

I provide an improved coupling structure for 1 the various space resonant regions defined by the radial vanes shown in plan View :in Fig. 2. This coupling means may comprise a single or a plurality of circular metallic conductors whichare inelectrical contact with the vanes 1, preferably .asclose to the inner extremities thereof as mechanicalexpediency will warrant. For example, 1:. provide circular-conductors 4| and-42 lyingin .;grooves-r4 3 and-44 so as to be substantially flush with the upper surface, or top surface, -of,the aanode. structure d.

:.Conductor@4 I: is-electrically connected to vanes la, 1e, 1e and lg, being in electrical contactwlth fthe- 'walls of ,grOOVGSHlQfiIld not-being in contact with'the alternate .or intermediatevvanes due to the fact that grooves 44. are of sufficient size I to permit the passage of :the conductor therethrough without contacting the intermediate vanes. Conductor 12,. on the other hand, .electrically connects vanes lb, 51d, 'lfandlh, .counotbeing in contact with the vaneslaflq'i-le and lg. 'Theplan'of coupling the vanes*1a-'-lh,,in-

elusive, mayibein accordance with that disclosed and claimedwin my copending-patent applicaitiont-Serial No. 162,123, filedDctober 15, 1942 ,55 and which is assignedzto'thezassigneelofithe. present application.

1' Conductorstl and-'42 need not be continuous,

. and! the'length' thereof, or the number of vanes to @which each of these conductors; is connected 'n1ay be chosen torestabli'slr the desired mode of l' Qp8Iati0I1.0f theqdischarge device-as a wholeso that the :operatingv frequency or [mode 'is..determinable.

lfhrdesired a similar coupling structuremay be .65: provided-.inthe bottom ofthe anode structure. 'Suchuan .,arrangement is :illustrated in Fig. 1 wherein additional coupling conductors -and All: are shown, lying in grooves or slots in the bot- -:tomsplane of the anode structured.

.1An important feature I of apparatus built. :in raccordance-rwith .;my-=invention is: the increased efliciencyrobtainable by. the proper: dimensioning of lthewradialwvane-thicknessvwith respect to the spacing therebetweenzat the region immediately 1 opposite the: cathode whereby there. is; an effective concentration of the electric field incident to the electromagnetic fields within the respective space resonant regions. In this manner there is provided eificient transmission of energy from the oscillating space discharge to the space resonant regions.

Another important advantage is the provision of the coupling means at the extremities of the radial vanes, which positioning accomplishes most efiective coupling of the various regions. One of the desirable objects of any coupling means in a device of this type, of course, is the frequency selection or the mode of operation at which it is desired to operate the device as a whole. With the coupling means at the inner extremities of the radial vane T, I have found that the frequency selection or mode of operation is highly discriminatory or predeterminable.

A further advantage of apparatus built in accordance with my invention is the simplified construction which lends itself to factory production methods and apparatus. It will be readily apparent upon inspection of the structure that the ring 5 may be readily slotted to receive the radial vanes I and that the radial vanes may be easily inserted into the slots 6 so provided. Furthermore, as concerns the machining operations of the groove 43 and 44 which receive the circular and flexible coupling conductors 4| and 42, the vanes I may be slotted or grooved prior to insertion into the grooves 6, and due to the fact that the vanes are rectilinear in configuration a relatively large number of similar vanes may be machined in one operation by placing the vanes in juxtaposition in the grooving or slotting machine.

While I have shown and described my invention as applied to a particular device, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric discharge device of the magnetron type comprising an envelope, a plurality of electrodes within said envelope including a cathode and an open-ended cylindrical anode structure surrounding said cathode, said anode structure comprising an annular ring portion and a plurality of vanes extending radially inwardly from said cylindrical portion, the inner ends of said vanes and said cathode bounding a substantially annular interelectrode space, means coupling together the cavity resonators defined by said vanes, said means comprising on each end of said anode structure a pair of annular metallic rings near the ends of said vanes facing said cathode, one of said rings in each of said pair being electrically connected to alternate vanes, the other of said rings in each said pair being electrically connected to the vanes intermediate between said alternate vanes.

2. A device as in claim 1 including within said envelope magnetic members adjacent the opposite ends of said anode structure for establishing a magnetic field in the region between said cathode and said anode structure.

3. An electric discharge device of the magnetron type comprising an envelope, a plurality of electrodes Within said envelope including a cathode and an open-ended cylindrical anode structure surrounding said cathode, said anode structure comprising an open-ended metallic cylinder and a plurality of vanes extending radially inwardly from said cylinder, said vanes having uniform thickness substantially greater than the distances between adjacent vanes at their inner extremities, the ends of said vanes and said cathode bounding an annular interelectrode space, means coupling together the cavity resonators defined by said vanes, said means comprising on each end of said anode structure a pair of concentric annular metallic rings positioned within grooves in said vanes near the ends of said vanes facing said cathode, one of said rings in each of said pair being electrically connected to alternate vanes, the other of said rings in each said pair being electrically connected to the vanes intermediate between said alternate vanes.

4. A device as in claim 3 including within said envelope magnetic members adjacent the opposite ends of said anode structure for establishing a magnetic field in the region between said cathode and said anode structure.

RALPH J. BONDLEY.

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

UNITED STATES PATENTS Number Name Date 2,063,342 Samuel Dec. 8, 1936 2,147,159 Gutton et al Feb. 14, 1939 2,187,149 Fritz Jan. 16, 1940 2,247,077 Blewett et al June 24, 1941 2,259,690 Hansen et a1 Oct. 21, 1941 2,305,781 Helbig Dec. 22, 1942 2,309,966 Litton Feb. 2, 1943 2,408,235 Spencer Sept. 24, 1946 2,417,789 Spencer Mar. 18, 1947 FOREIGN PATENTS Number Country Date 215,600 Switzerland Oct. 16, 1941 509,102 Great Britain July 11, 1939

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