US3553524A

US3553524A - Magnetron with improved vane and strap structure

Info

Publication number: US3553524A
Application number: US789131A
Authority: US
Inventors: Donald G Hill
Original assignee: Litton Precision Products Inc
Current assignee: Northrop Grumman Guidance and Electronics Co Inc
Priority date: 1969-01-06
Filing date: 1969-01-06
Publication date: 1971-01-05
Anticipated expiration: 1988-01-05
Also published as: DE1958394B2; DE1958394A1; GB1245506A; FR2027819A1; NL137275C; NL6918451A; JPS513192B1; SE345340B

Abstract

A vane and strap type magnetron is presented which includes a unique slot arrangement for receiving a thin strap. A first relatively large opening is located proximate but spaced from the vane tip. A second opening in the form of a slot-like passage is located in the vane between the first opening and vane tip to form a passage therebetween. The strap is, broadly speaking, of a relatively flat washer-like geometry and fits through the slotlike opening into a position in the large opening and in that position avoids contacting the vane. A second slot-like opening is vertically spaced from the above mentioned openings and provides a snug fit for a second horizontally spaced vane strap. The method of the invention includes an assembly procedure in which the vanes are pushed onto the straps.

Description

United States Patent Inventor Donald G. Hill Montoursville, Pa.

Appl. No. 789,131

Filed Jan. 6, 1969 Patented Jan. 5, 1971 Assignee Litton Precision Products, Inc. San Carlos, Calif. a corporation of Delaware MAGNETRON WITH IMPROVED VANE AND STRAP STRUCTURE 3,027,488 3/1962 Winsor..... 315/39.69X 3,418,523 12/1968 Schmidt 315/3965 3,423,632 1/1969 Uchimaru et a1.. 315/3969 ABSTRACT: A vane and strap type magnetron is presented which includes a unique slot arrangement for receiving a thin strap. A first relatively large opening is located proximate but 9 Claims 14 Drawing Figs spaced from the vane tip. A second opening in the form of a US. Cl 3l5/39.69, slot-like passage is located in the vane between the first open- 3 l5/39.7 5 ing and vane tip to form a passage therebetween. The strap is, Int. Cl. .1101] 25/50, broadly speaking, of a relatively flat washer-like geometry and H01 j 23/22 fits through the slot-like opening into a position in the large Field of Search 315/3951, opening and in that position avoids contacting the vane. A 39.65, 39.69, 39.75 second slot-like opening is vertically spaced from the above mentioned openings and provides a snug fit for a second References Cited horizontally spaced vane strap. The method of the invention UNITED STATES PATENTS includes an assembly procedure in which the vanes are pushed 2,837,696 6/1958 LaRue 315/39.69X Onto the Strapsa 4 11 f 22 r 7 Q l I I 4 J6 17 .19 3

PATENTEUJ m am y 3553524 sum 3 or 3 I PMM M- Arman 5r MAGNETRON WITH IMPROVED VANE AND STRAP STRUCTURE This invention relates to magnetrons and, more particularly, to an improved vane and strap Construction for magnetrons.

The magnetron is a well known electron discharge device used to generate electromagnetic fields in the microwave frequency range. Conventionally, the magnetron includes a cylindrical cathode, a cylindrical anode surrounding the cathode, and a plurality of resonant cavities formed in the anode by either slots or vanes. An electric field is established between the cathode and the anode and a magnetic field is applied perpendicular to the electric field in the interaction region, a space between the cathode and the resonant cavities in the anode. When the value of E/H is suitable, electrons emitted from the cathode interact with the electric and magnetic fields togenerate microwave energy of a frequency determined by the parameters and the resonance characteristics of the cavities.

One of the earliest problems with magnetrons was caused by moding; that is, significant cavity response occurred {at frequencies other than the frequency for which the magnetron was designed to operate. In turn, these spurious responses produced fields which caused undue heating of the cathode, in addition to putting undue limits on operating efficiency. The concept of anode strapping was devised as one solution to these problems.

Strapping as conventionally understood is the joining together of alternate anode vanes, each pair of which form a resonant cavity therebetween, thus maintaining all such cavi ties at the same electrical potential; and, thus alternate anode vanes ideallywere locked into operation in the 1r mode which had node points of the same distance apart as the distance between alternate vanes. With this constraint other spurious modes having nodal points elsewhere were removed to far higher frequencies. A full explanation of the objects and purposes of strapping the magnetron vanes is presented in U.S. Pat. 2,417,789 and in U.S. Pat. 2,550,614. In the latter patent a magnetron construction is illustrated in which a strap is placed on both the top and the bottom of the anode varies. in other instances, as illustrated in U.S. Pat. 2,649,556, additional pairs of straps are located on the top and bottom of the vanes in another conventional construction termed double strapping.

It was recognized early that the location of the straps on the vanes is a significant factor in maintaining the operation of the magnetron in the desired mode. It was realized that locating straps on the top and bottom edges of the vane was less effectual than locating the straps on the edge of the vanes which faces the cylindrical cathode or vane tip, Accordingly, another patent, U.S. Pat. 2,432,827, presents a magnetron which has a strapping arrangement wherein the straps are located in slots cut in the edge of the vane facing the cathode or vane tip. While this latter structure provided the best strap location for purposes of maintaining the magnetron in the single mode of operation, it proved to have serious drawbacks that effectively precluded its use. At least two difficulties were recognized; namely, the currents which circulated in the straps equalizing the voltage on alternate vanes generated an electromagnetic field which because of its proximity to the cylindrical cathode actually interfered with the operation and performance of the magnetron. In turn, electrons emitted by the cathode bombarded the straps causing them to become highly resistive or completely melted which in turn destroyed the function of the straps. Hence, without effective strapping the magnetron could operate in an improper mode which resulted in the drawing of too much current from the cathode and eventual destruction of the magnetron.

Accordingly, while the location of straps in slots on the top and bottom of the vanes was not as effectual it provided the best practical compromise prior to this invention, since it avoided substantially creating electromagnetic fields in proximity with the cathode and also placed the straps out of the immediate area in which they could be subjected to electron bombardment.

To obtain many of the advantages attendant to center strapping without the inherent problem of electron bombardment the hole-in-the-vane type of strapping was devised. This vane and strap construction is illustrated pictorially for one in U.S. Pat. 3,076,122. In this structure alternate vanes were provided with holes located near the center of the vane and proximate to the vane tip. In so doing that portion of the strap which protrudes through the aperture in the vane is isolated from cathode bombardment by the vane tip. Additionally, the other portions of the straps which extended between vanes is in essence located within the resonant cavity formed between the two vanes. Accordingly, electrical fields normally established in the resonant cavity are such as to inhibit the entrance of bombarding electrons, and, accordingly provide protect ion for the strap. Moreover, the removal of the straps slightly into the resonant cavities inhibited the electromagnetic fields generated by currents flowing in the straps from interfering with the cathode.

The hole-in-vane construction, however, is not without serious economic disadvantage. The methods of strapping described heretofore and illustrated in the cited Spencer patents permit simple assembly operation; that is, notches or slots are formedin the vane ends; accordingly, in assembling the anode the straps could be dropped simply in place. However, with the described hole-in-vane construction each strap had to be formed initially in the shape of a split ring. Then each of the plurality of vanes had to be slipped onto the strap manually. In those alternate straps which had openings which were eventually to be sealed or brazed to the strap, the outer diameter of the strap cfoss section, and the inner diameter of the opening are essentially the same. The passage through the vane is essentially of a right cylindrical geometry whereas the ring shaped strap is essentially circular. Accordingly, in pushing the various vanes onto the ring shaped strap one is effectively attempting to put a bent circular shaped body of circular cross section through a right cylindrical passage of essentially the same diameter as the cross section. This relationship causes the two ends of the cylindrical passage to hook onto or bind with portions of the circular strap. Such binding between the elements makes assembly exceedingly difficult: the vane must be carefully moved or jockeyed into its angular position along the strap in order to avoid undue bending or distortion in shape of the latter. As is apparent, this is a very difficult and time consuming procedure and accordingly a very expensive one.

Therefore, it is an object of the invention to provide a new vane and strap construction for a magnetron which possesses all of the electrical advantages of the center strapped vane construction and which is easily and quickly assembled; and

It is an additional object of the invention to provide a novel center strap-vane arrangement in a magnetron in which the straps are isolated from destructive electron bombardment;

It is a still further object of the invention to provide a strap and vane construction for a magnetron and method of assembly therefore which provides the advantages of a hole-invane construction but which is assembled in a more simple and expeditious manner.

Briefly stated, the invention includes in a magnetron having a vane with a vane tip facing the'cathode, a passage or aperture through said vane spaced from the vane tip; and a second slot-like passage aperture through the vane smaller in cross section than said first which forms a passage between the vane tip and said first passage.

Additionally, in accordance with the invention a thin strap having generally a washer-like shape located so that it passes through the first aperture without contacting the vane.

Further in accordance with the invention, each vane includes a second slot vertically spaced from the other aperture which extends from the vane tip facing the cathode to a predetermined distance into the vane which is of the same height as the height of the first slot. A second strap identical in construction with the first strap is positioned in this slot by inserting same from the vane edge. The depth of this second slot is greater in dimension than the annular portion of the strap. Preferably, however, a protrusion is included on this portion of the strap which protrudes radially inwardly to fill the remaining portion of this second slot.

Further in accordance with another aspect of the invention, the portion of the strap which is inserted into this second slot includes a notch along the outer periphery thereof which extends radially inwardly so that the sides of the slot engage the side surfaces of the vane to thereby permit the vane during assembly to be self-aligning. Additionally, it is preferred that the strap be as thin as possible and that the length of the slot-like passage is at least twice as great as its height. Moreover, the thickness of height of the strap is slightly smaller than the height of the slot in order to permit the strap to slide therethrough from the direction of the vane tip into the first aperture.

Advantageously, a double strap vane arrangement is assembled in accordance with another aspect of my invention by simply spacing the straps a distance apart equal to the distance between the first and second slots in each vane and pushing the vanes onto the straps whereby a portion of the strap proceeds through the slot-like opening to a final location within the larger passage connected therewith while the second strap is pushed fully into the second slot and abuts the back end thereof.

The foregoing and other advantages and features which are believed to be characteristic of the invention both as to its organization and method of operation together with further objects and advantages thereof are better understood from the following description considered in connection with the accompanying drawings in which an embodiment of the invention has been illustrated by way of example.

In the drawings:

FIG. 1 shows a top view of a portion of a magnetron which embodies the novel vane and strap construction of my invention;

FIG. 2 is a cross section of the embodiment of FIG. 1 taken along the lines A-A;

FIGS. 3a and 3b illustrate a single strap of the preferred geometry used in the preferred embodiment of the invention;

FIG. 4 shows a side view of a strap constructed in accordance with the teachings of the invention;

FIGS. 5a 5b, and Scillustrate side views of vanes constructed in accordance with the teachings of the prior art, and FIG. 5d illustrates a portion of FIG. 50; and

FIGS. 6, 7, 8a, 8b, and 9 illustrates the various steps followed in assembling by a novel method the preferred embodiment of the invention.

FIG. 1 is a top view of a portion of a conventional vane and strap magnetron modified to embody the vane and strap construction of the invention. Consideration of FIG. 1 may be taken together with the illustration of FIG. 2 which is a sectional side view taken along the lines A-A of the embodiment of FIG. 1. Seen from the top in FIG. 1 is the anode l. Anode 1 has a substantially cylindrical hollow geometry and is of electrically conductive material. Attached to and projecting inwardly from the inner cylindrical wall of the anode are an evenly spaced plurality of eight

vanes

2, 3, 4, 5,6,7, 8, and 9. The vanes are generally rectangular bodies of electrically conductive material which geometry is better illustrated in FIG. 2. Each of the vanes shown in FIG. 1 projects from the anode wall to within a predetermined distance of a cylindrical cathode 10 essentially located in the center of and having its axis concentric with the axis of the cylindrical anode. The vanes are evenly spaced about the walls of anode 1. The spaces between adjacent vanes form eight identical resonant cavities, 12, each of which is resonant at the frequency to which the magnetron is designed to generate high frequency energy. In addition, the annular space surrounding cathode 10 between the tips of vanes 2 through 9 and the surface of cathode 10 is conventionally termed the interaction region. An'exemplary output coupler 14 for coupling microwave energy out of the magnetron is illustrated in the FIG.

In the preferred construction of the invention the magnetron contains two electrically conductive straps l5 and 16, one directly above the other. However, only upper strap 16 is visible in the section of FIG. 1. Strap 16 is connected to the vanes in the conventional manner; that is, it is physically connected to sets of alternate vanes so that it electrically joins those vanes together; whereas it is insulated from and does not contact the intermediate vanes, those between the alternate vanes. For purposes of better illustrating this construction a portion of two adjacent vanes 3 and 4 are cutaway to expose the underlying portion of strap 16. Cutaway portion of vane 3 is represented by the number 19; and cutaway portion'of the adjacent vane 4 is represented by number 20 in FIG. 1. As illustrated, strap 16 is generally annular shaped washer-like member of electrically conductive material. That portion of the strap between vane 3 includes a radially inwardly projecting portion 17 which fills in a slot in the vane and a slight notch or slot 18 on its outer periphery in which the strap anchors in the vane. Strap 16 is in direct physical contact with vane 3. However, adjacent vane 4 does not physically contact with strap 16 but merely passes through a passage 22 therethrough.

The side view of FIG. 2 is a cross section of the anode portion of a magnetron illustrated in FIG. 1 taken along the lines A-A. This illustration permits a full side view of the two vanes 3 and 7 which are supported from the inner wall of cylindrical anode l. Cathode 10 is centrally positioned between the vane tips. For purposes of clarity the small portions of the vanes 4 and 5 and the edge of straps l5 and 16 which technically should be observed in this perspective have been omitted. Dotted line 19 represents the portion of the vane 3 which was cutaway in FIG. 1 in order to permit illustration of a portion of the upper strap 16.

Straps

15 and 16 are spaced apart vertically a predetermined distance and are inserted into openings formed in the anode vanes. While strap 16, as discussed, joined together the alternate vanes, strap 15 joins together the remaining or'intermediate vanes. Each vane has the two sets of openings or passages through the vane. One set is a slot-like passage 24 dimensioned so as to permit strap 16 to fit snugly therein. This vane opening is termed a contacting passage. The second opening consists of two passages; a larger passage 26, which corresponds to passage 22 in vane 4 of FIG. 1, having a cross section larger than the cross section of the strap 15 so as to permit the strap to pass therethrough without physically contacting any portion of vane 3; and a smaller slot-like passage 28 which extends from the vane tip, which faces the cathode 10, to the larger passage 26. This second set of openings is termed a noncontacting passage. Slot-like passage 28 is of a height sufficient to permit passage therethrough of strap 15 during the assembly procedure.

The vanes and straps are suitably angularly oriented and spaced so that the strap 16 fits into the contacting type passage in one vane and passes through the noncontacting type passage in the adjacent vanes without contact. Hence, the straps electrically join and are physically supported by only alternate ones of the vanes.

Moreover, the relationship between the dimensions of the slot passage in the noncontacting passage, such as slot 28, and the cross section of the strap, such as strap 15, is preferably such that the length of that portion of the passage is at least twice as great as its height while the height of the passage is slightly greater than the thickness of the strap.

A complete magnetron includes numerous other elements such as the complete container, connections for supplying voltages and currents to the anode and cathode, a filament, sockets, permanent magnets or other magnet means, magnetic pole pieces, etc. However, these additional elements are all conventional; and the inclusion of same in .this disclosure would not aid in the understanding of the invention. Accordingly, they are not presented.

The reader may make reference for those details to the multitude of available patents showing various constructions of vane and strap magnetrons and to other literature available to those acquainted with the subject of magnetrons.

FIGS. 3a and 3b a section of FIG. 1 taken along the line 8-8, show in greater detail the'physical geometry of each strap in the preferred embodiment of the invention, such as was illustrated in the preceding figures. Strap 30 is a relatively thin flat washer-like element of conductive material. A plurality of inwardly projecting portions or protrusions 32 equal in number to the number of vanes with which the strap is to electrically join and, hence, equal to one-half the number of vanes in the anode assembly are shown. These protrusions are of such dimension as to fill in the space fonned in the contacting type passages in the vanes as is shown in FIG. 2 or such as slot 45 in FIG. 4.

7 At the same angular location about strap 30 in which protrusions 32 are provided small notches or slots 34, previously described,are formed along the outer periphery. These slots tend to make the assembling together of strap and vane self-aligning that is, the back of the strap slot engages the back wall of the vane slot while the two side walls of the slot engage the side walls of the vane. This engagement tends to inhibit lateral movement between the vane and strap during the assembly procedure.

As illustrated in FIG. 3b the strap is thin;" that is, the width dimension, 36, of the cross section of the annular portion is equal to or greater than twice its height dimension or thickness, 38. Ideally the strap is made as thin as is possible.

FIG. 4 illustratesa side view of a single anode vane 40 constructed in accordance with the invention. The vane contains the two sets of openings, one above the other, for accommodating two straps in the manner illustrated and discussed with respect to FIGS. 1 and 2. The noncontacting type passages include the larger passage 42 spaced from but proximate the vane, tip 43. Passage 42 is larger in both width and height than, the corresponding dimensions of the portion of a strap, indicated by the dashed lines, which is to pass therethrough when assembled. The noncontacting type passage includes the second slot-like passage or opening 44 which provides a passage between the vane tip 43 and passage 42; thus forming a passage for insertion of the strap from the vane tip end of vane 40 through passage 44 and to a final position within passage 42. As previously noted, the length of the slot-like passage 44 is preferably at least twice as great at its height. In addition, the height of passage 44 is sufficient to permit a strap to pass therethrough in assembly.

The contacting type passage isshown as slot-like passage 45. This passage extends from vane tip 43 back into the vane to a predetermined depth less than that of passage 42, but greater than that of passage 44. The height of slot-like passage 45 is sufficient to allow the strap to be inserted and fit snugly therein.

For comparison, schematics of types of prior art methods of vane strapping are illustrated in FlGS. 5a 5b and 5c FIG. 5a illustrates in cross section a double strapping arrangement on the top and bottom edges of the vane. This includes a first pair of straps 51 and 52 and a second pair of straps 53 and 54 which are located in slots, one wider than the other located in the vane and on the top 55 and bottom 56 edges of vane 57 away from the vane tip 58 or cathode facing edge. This is the construction that is almost universally employed as a compromise. Since it is located remote from the center of the vane and vane edge 58, it is not as effective to prevent moding as the construction of FIG. 5b However, it does not have the attendant disadvantages to the construction of FIG. 5b since it is not directly exposed to electrons from the cathode and does not produce as substantial fields which interfere with the operation of the cathode.

FIG. 5b represents vane edge or center strapping, as variously termed, in which straps 61 and 62 are located in slots, one wider than the other, in the vane tip edge 63 of vane 64. Note that strap 61 is exposed to electrons coming from the cathode toward vaneedge 63.

FIG. 50 illustrates in cross section the hole-in-vane type center strapping with straps 65 and 66 extending through holes through vane 67. One hole 68 is large enough to prevent contact with strap 65 which protrudes therethrough in accordance with the conventional requirements of strapping alternate vanes. As is apparent, the metal vane protects the straps from electrons emanating at the cathode coming from the direction of the cathode facing edge or vane tip 69. Moreover, it is removed from the vane edge and consequently does not generate substantial fields which would interfere with the operation of the cathode. The disadvantage of this construction is in its cost of assembly as in hereinafter made evident.

FIG. 5d represents pictorially the difficulties encountered during the assembly of the hole-in-vane type strapping construction. An enlarged cross section of the vane around the portion of the straps which contacts the vane, such as strap 66 in FIG. 50 is illustrated. Each strap in FIG. 5c is in the shape of a split ring which is cut open and spread apart slightly, similar to a chain link, and. the vanes are pushed onto the strap, individually, then spaced, and the strap is reclosed. Thus, the passage or hole-'70 in vane 67' which corresponds to the hole in which the strap 66 of FIG. 50 protrudes is seen to be rectangular in cross section, and is substantially a right cylindrical passage. By contrast, the strap 66 in the form of a ring is of a circular geometry. Accordingly, as vane 67 is pushed onto strap 66' some binding occurs at points 7 I and 72 due to this dissimilar geometry and each vane as it is pushed onto strap 66' must be carefully and slowly jockeyed into place to avoid mechanically bending or distorting the shape of strap 66'. This problem is multiplied by the number of vanes to be assembled.

The construction of the present invention'combines the electrical advantages of the hole-in-strap type construction of FIG. 50 with the ease of assembly possible with the center strapped slot construction, such as represented by FIG. 5b as hereinafter brought out in a preferred method of assembly hereinafter set forth. Moreover, it has been found that the limited exposure of straps made possible by the intermediate passage in the strap, such as 28 in-FIG. 2, has not created any serious problems. p

In FIG. 6

straps

75 and 76 are inserted on a splined rod 77. The splines are not illustrated in this FIG. The recesses in the splined rod correspond in number to double the number of projecting portions on any one strap and equal to the number of vanes. The straps are spaced by means of

spacers

78 and 79 which rest upon the jig bottom 80 through which splined rod 77 is inserted.

Spacers

78 and 79 are moved in from the side and the lowermost strap 76 is placed and fits within a recess or slot therein. The uppermost strap 75 rests on the top surface of

spacers

78 and 79. Note that the top and bottom straps are angularly oriented about rod 77 so that the projecting portions of one strap is aligned with the space between two projecting portions of the other strap. A washer shaped member 81 fits over the top of rod 77 and holds upper strap 75 in place on top of the spacers.

In the next step shown in I FIG. 7 the

vanes

82 and 83 are pushed in from the side. That is, they maybe slid along jig bottom 80 and pushed onto

straps

75 and 76 which are spaced and sized in accordance with the teachings of the invention to fit within the slots in each vane. The vane is pushed along until the vane edge abuts the back of the slot or spline in rod 77. As is apparent from the invention, the vanes are alternated so that the narrow slot on one vane is aligned with the wide slots on each adjacent vanes and the narrow slot is aligned with a projecting portion of each strap.

It is noted that the vanes may be pushed into position concurrently or consequently or in any order, and manually or with machines adapted for this purpose, automatically. Washer 81 is removed. The

spacers

79 and 80 may be removed during or before this step, but preferably not before at least two vanes substantially displace suitably diametrically opposed from another have been pushed into place so that they may subsequently perform the functions of the spacers.

FIGS. 8a and 8b illustrate a portion of the assembly during the preceding steps and shows the relationship and configuration of the elements. FIG. 8a shows a top section of the splined rod 77', vanes 82' and 81 in place and sectioned to show of rod 77, center plug 90 is slightly wider than rod 77 and consequently exerts a force on the vane edges radially outward toward the cylindrical anode wall 84 which causes the back edge of

vanes

82 and 83 to press against the anode wall. Accordingly, the back edges are suitably prepared to be soldered to the back wall of the anode by conventional soldering and brazing procedures.

Inasmuch as the improvement relates to the manufacture or method of building the anode-vane-strap construction which is used as an element in a conventional magnetron the remaining steps which are used to complete the magnetron are other-' wise conventional or conventional choices. Accordingly, they need not be further discussed.

A further note may be added however, on the brazing procedure for the straps and vanes. Normally those slots or passages in the vanes which support and contact the straps have dimensioned tolerances which permit between them a slip-fit or snug-fit, as variously termed. Pieces or wires of copper gold brazing alloy, termed solder hooks, are placed against the juncture of the strap and vane and when heated to the appropriate brazing temperatures form a bond or weld between the vanes and straps. Alternatively a novel procedure may be used instead. Then the strap, which is preferably of monel, a copper nickel alloy, may be precoated with a thin coating of gold covered by a thin coating of copper and that the strap so coated fits snugly in the slot prior to heating. In this instance the bond or weld between the vane and strap is formed merely by heating to the appropriate brazing temperature.

It is to be understood that the above-described arrangements are intended to be illustrative of the application of the principles of the invention and are not intended to limit the invention. Since numerous equivalents suggest themselves to those skilled in the art which do not depart from the spirit and scope of the disclosed invention, it is to be expressly understood that the invention is to be broadly construed within the spirit and scope of the appended claims.

I claim:

1. In a magnetron of the vane and strap type which includes a cylindrical anode; a plurality of anode vanes spaced about and projecting radially from a cylindrical anode wall to within a predetermined distance of an axially located cylindrical cathode, with the vane tips of each of said vanes facing said cathode;and first and second vane straps spaced from one another, said first strap being in contact with alternate ones of said vanes without contacting intermediate ones of said vanes for providing an electrical connection between said alternate vanes and said second strap being in contact with intermediate ones of said vanes without contacting said alternate vanes for providing an electrical connection between said intermediate vanes:

the invention wherein said alternate vanes at a first predetermined location thereof and said intermediate vanes at a second predetermined location thereof each in- 'clude:

a first aperture therethrough located proximate the vane tip; said first aperture being larger in dimension than the corresponding dimensions of an annular portion of a vane strap;

and a second slotlike aperture of smaller height than the corresponding height of said first aperture; said second slotlike aperture extending and forming a passage between said vane tip and said first aperture for permitting said vane during assembly to be inserted over said strap to locate said strap in said first aperture;

and wherein said intermediate vanes at a first predetermined location thereof and said alternate vanes at a second predetermined location thereof each include:

a third slotlike aperture, said third slotlike aperture extending from the vane tip a predetermined distance into said vane for contacting and therewithin receiving a strap; said third slotlike aperture having approximately the same height as the height of said second aperture of said vanes;

and wherein each said first and second straps comprise a relatively thin flat continuous annular member having a thickness dimension slightly less than the height dimension of said second and third apertures;

said first strap being situated in said third slotlike aperture in said intermediate vanes for providing an electrical connection therebetween and extending through said first apertures of said alternate vanes without contact with said alternate vanes; and said second strap being situated in said third slotlike aperture in said alternate vanes for providing an electrical connection therebetween and extending through said first apertures of said intermediate vanes without contact with said intermediate vanes.

2. The invention as defined in claim I wherein each said strap includes: a plurality, equal in number to one-half the number of vanes, of projecting portions each of which protrudes radially inwardly from the inner periphery of said annular member, each of said projections located within a corresponding one of said third slotlike apertures in which said annular member is situated to fill said respective third slotlike apertures up to the vane tip.

3. The invention as defined in claim 2 wherein each said strap further includes: a plurality of shallow slots, equal in number to one-half the number of vanes, located evenly spaced along the outer periphery of said annular member, each said shallow slot having a bottom located within a corresponding one of said third slotlike apertures in which said annular member is situated and having sides in contact with the sides of the vane that includes said corresponding third slotlike apertures for enhancing alignment during assembly between said vanes and said strap.

4. A magnetron anode for a magnetron of the type containing a cylindrical anode having a plurality of spaced vanes projecting from said anode and surrounding a cylindrical cathode, with each of said vanes having a tip facing said cathode, and said anode includes at least first and second annular shaped vane straps, wherein intermediate ones of said plurality of vanes are connected by said first strap and the alternate ones of said plurality of vanes are connected by said second strap;

the invention wherein each alternate vane includes a first opening spaced from the vane tip, said first opening being larger in dimensions than corresponding dimensions of an annular portion of said first strap;

a second slotlike passage extending between said vane tip and, said first opening for permitting said vane during assembly to be inserted over said strap to locate said strap in said first opening;

wherein each intermediate vane includes a third slotlike passage extending into said vane from said vane tip for contacting and therewithin receiving said first strap; and

wherein said first strap comprises a relatively thin fiat continuous annular washer-shaped member having a plurality of equally spaced thin and flat projecting portions protruding radially inwardly from the inner periphery of said annular portion; said plurality of projecting portions in said first strap corresponding in number to one-half the number of vanes in said plurality of vanes and being located in corresponding ones of said third slotlike passage in said intermediate vanes.

aligned with said projections for enhancing alignment during assembly between said intermediatevanes and said first strap.

7. In a magnetron anode for a magnetron of the vane and strap type in which an even numbered plurality of anode vanes each having a vane tip are evenly spaced around and project radially inwardly from a cylindrical surface and in which a first strap contacts intermediate ones of said vanes without con tacting alternate ones of said vanesfor providing an electrical connection between said intermediate vanes, the invention wherein said alternate vanes each include at a first predetermined location thereof:

a first aperture therethrough located proximate the vane tip,

said first aperture being larger in dimensions'than corresponding dimensions of an annular portion of said strap;

a second slotlike aperture of smaller height than the corresponding height of said first aperture, said second slotlike aperture extending and forming a passage between said vane tip and said first aperture for permitting said vane during assembly to be inserted over said strap to locate said strap in said first aperture; and wherein said intermediate vanes each include: at a predetermined location thereof;

a third slotlike. aperture, said third slotlike aperture extending from the vane tip into said vane a predetermined distance for contacting and therewithin receiving said strap, said third slotlike apertune being of approximately the same height as said second aperture of said alternate vanes; and wherein said strap comprises;

a relatively thin flat continuous annular member, said annular member having a thickness slightly less than the height of said second and third apertures, said strap being situated in said third slotlike aperture in said intermediate vanes for providing electrical connection therebetween and extends through said first apertures of said alternate vanes without contactwith said alternate vanes.

8. The invention as defined in claim 7 wherein said second slotlike aperture is of a predetermined length and height said length thereof being at least twice as great as said height 9. The invention as defined in claim 8 wherein said strap includes a shallow slot at each of those plurality of angular locations along the outer periphery thereof within said third slotlike aperture of each of said intermediate vanes; and wherein the back end of said third slotlike aperture in each vane is positioned within a corresponding shallow slot in said strap for enhancing alignment between said vanes and strap during assembly.

Claims

1. In a magnetron of the vane and strap type which includes a cylindrical anode; a plurality of anode vanes spaced about and projecting radially from a cylindrical anode wall to within a predetermined distance of an axially located cylindrical cathode, with the vane tips of each of said vanes facing said cathode; and first and second vane straps spaced from one another, said first strap being in contact with alternate ones of said vanes without contacting intermediate ones of said vanes for providing an electrical connection between said alternate vanes and said second strap being in contact with intermediate ones of said vanes without contacting said alternate vanes for providing an electrical connection between said intermediate vanes: the invention wherein said alternate vanes at a first predetermined location thereof and said intermediate vanes at a second predetermined location thereof each include: a first aperture therethrough located proximate the vane tip; said first aperture being larger in dimension than the corresponding dimensions of an annular portion of a vane strap; and a second slotlike aperture of smaller height than the corresponding height of said first aperture; said second slotlike aperture extending and forming a passage between said vane tip and said first aperture for permitting said vane during assembly to be inserted over said strap to locate said strap in said first aperture; and wherein said intermediate vanes at a first predetermined location thereof and said alternate vanes at a second predetermined location thereof each include: a third slotlike aperture, said third slotlike aperture extending from the vane tip a predetermined distance into said vane for contacting and therewithin receiving a strap; said third slotlike aperture having approximately the same height as the height of said second aperture of said vanes; and wherein each said first and second straps comprise a relatively thin flat continuous annular member having a thickness dimension slightly less than the height dimension of said second and third apertures; said first strap being situated in said third slotlike aperture in said intermediate vanes for providing an electrical connection therebetween and extending through said first apertures of said alternate vanes without contact with said alternate vanes; and said second strap being situated in said third slotlike aperture in said alternate vanes for providing an electrical connection therebetween and extending through said first apertures of said intermediate vanes without contact with said intermediate vanes.

2. The invention as defined in claim 1 wherein each said strap includes: a plurality, equal in number to one-half the number of vanes, of projecting portions each of which protrudes radially inwardly from the inner periphery of said annular member, each of said projections located within a corresponding one of said third slotlike apertures in which said annular member is situated to fill said respective third slotlike apertures up to the vane tip.

4. A magnetron anode for a magnetron of the type containing a cylindrical anode having a plurality of spaced vanes projecting from said anode and surrounding a cylindrical cathode, with each of said vanes having a tip facing said cathode, and said anode includes at least first and second annular shaped vane straps, wherein intermediate ones of said plurality of vanes are connected by said first strap and the alternate ones of said plurality of vanes are connected by said second strap; the invention wherein each alternate vane includes a first opening spaced from the vane tip, said first opening being larger in dimensions than corresponding dimensions of an annular portion of said first strap; a second slotlike passage extending between said vane tip and said first opening for permitting said vane during assembly to be inserted over said strap to locate said strap in said first opening; wherein each intermediate vane includes a third slotlike passage extending into said vane from said vane tip for contacting and therewithin receiving said first strap; and wherein said first strap comprises a relatively thin flat continuous annular washer-shaped member having a plurality of equally spaced thin and flat projecting portions protruding radially inwardly from the inner periphery of said annular portion; said plurality of projecting portions in said first strap corresponding in number to one-half the number of vanes in said plurality of vanes and being located in corresponding ones of said third slotlike passage in said intermediate vanes.

5. The invention as defined in claim 4 wherein said second slotlike passage is of a predetermined length and height said length thereof being at least twice as great as said height

6. The invention as defined in claim 5 wherein said first strap includes further a plurality of slots along the outer periphery thereof corresponding in number and angularly aligned with said projections for enhancing alignment during assembly between said intermediate vanes and said first strap.

7. In a magnetron anode for a magnetron of the vane and strap type in which an even numbered plurality of anode vanes each having a vane tip are evenly spaced around and project radially inwardly from a cYlindrical surface and in which a first strap contacts intermediate ones of said vanes without contacting alternate ones of said vanes for providing an electrical connection between said intermediate vanes, the invention wherein said alternate vanes each include at a first predetermined location thereof: a first aperture therethrough located proximate the vane tip, said first aperture being larger in dimensions than corresponding dimensions of an annular portion of said strap; a second slotlike aperture of smaller height than the corresponding height of said first aperture, said second slotlike aperture extending and forming a passage between said vane tip and said first aperture for permitting said vane during assembly to be inserted over said strap to locate said strap in said first aperture; and wherein said intermediate vanes each include at a predetermined location thereof; a third slotlike aperture, said third slotlike aperture extending from the vane tip into said vane a predetermined distance for contacting and therewithin receiving said strap, said third slotlike aperture being of approximately the same height as said second aperture of said alternate vanes; and wherein said strap comprises; a relatively thin flat continuous annular member, said annular member having a thickness slightly less than the height of said second and third apertures, said strap being situated in said third slotlike aperture in said intermediate vanes for providing electrical connection therebetween and extends through said first apertures of said alternate vanes without contact with said alternate vanes.

8. The invention as defined in claim 7 wherein said second slotlike aperture is of a predetermined length and height said length thereof being at least twice as great as said height

9. The invention as defined in claim 8 wherein said strap includes a shallow slot at each of those plurality of angular locations along the outer periphery thereof within said third slotlike aperture of each of said intermediate vanes; and wherein the back end of said third slotlike aperture in each vane is positioned within a corresponding shallow slot in said strap for enhancing alignment between said vanes and strap during assembly.