US2733381A

US2733381A - geier

Info

Publication number: US2733381A
Authority: US
Publication date: 1956-01-31
Anticipated expiration: 1973-01-31

Description

Jan. 31, 1956 L. w. GEIER 2,733,381

MAGNETRON TUNING STRUCTURES Filed Aug. 28, 1952 2 Sheets-Sheet l 4 i .s 2 5 2 JL 27 Z 2/ I a awe/won LEONAQD W. 695/; BY 61% W 3 ATTORNEY Jan. 3], 1956 w, GE|ER MAGNETRON TUNING STRUCTURES 2 Sheets-Sheet 2 Filed 4m 28, 1952 q A)? g p w mm vm e o .WGQOW WW A my 2,733,381 MAGNETRON TUNING STRUCTURES Application August 28,1952, Serial No. 306,873 Claims. (Cl..31539.61)

This invention relates to electron discharge devices of the magnetron type and, more particularly, to tuning structures used for varying the operating frequency of said devices.

In conventional magnetron tuning structures, the support members on which the tuner is mounted pass through apertures in the upper magnetic pole piece and are rigidly attached to a movable member above the pole piece which is hermetically sealed by a flexible seal, such as a bellows, to the remainder of the envelope of the device. It has been found that high frequency energy present in the magnetron .cavities will feed through the apertures surrounding the tuner support members in various regions of the tuning range and will excite resonances at frequencies determined by the geometry of tuner support structures which, in many cases, are so close to the operating frequency of the magnetron as to cause serious interference therewith.

This invention discloses that the energy may be substantially prevented from passing through the apertures in the pole piece, through which the tuning support members pass, by positioning resilient shorting members around the tuner support members in the apertures in the pole piece such that said resilient members substantially contact both the support members and the pole piece.

Specifically, it has been found that the resilient members may comprise toroidal springs of tungsten or any other resilient conductive material which will withstand elevated temperatures.

Other and further objects and advantages of this invention will be apparent as the description thereof progresses, reference being had to the accompanying drawings wherein:

Fig. 1 illustrates a longitudinal cross-sectional view of a magnetron embodying this invention;

Fig. 2 illustrates a transverse cross-sectional view of the device shown in Fig. 1 taken along lines 22 of Fig. 1; and

Fig. 3 illustrates a partial longitudinal cross-sectional view of a second embodiment of the invention.

Referring now to Figs. 1 and 2, there is shown a magnetron discharge device comprising an anode structure having an anode ring 11. Extending inwardly from the inside of anode ring 11 are anode members 12 which are alternately connected, at their upper and lower edges near their inner ends, by conductive straps 13, according to well-known practice. A cathode structure 14, of conventional type, is positioned in the space defined by the inner ends of anode members 12 and is supported by a support structure 15, which extends down through an aperture in the lower magnetic pole piece 16 of the magnetron, which is hermetically sealed to anode ring 11. Support member 15 is hermetically sealed to magnetic pole piece 16 by means of an insulating seal, not shown. The structure disclosed thus far is conventional, and any desired magnetron anode and cathode configuration may be used.

United es Presto Extending downwardly into the cavities, defined by each pair of adjacent anode members, is a plurality of tuning elements 17. The tuning elements 17, as shown here by way of example, extend into the cavities in the inductive regions thereof adjacent the anode ring 11 and accordingly tune the cavities substantially entirely by eddy current tuning. However, the tuning elements may extend into the cavities adjacent their inner ends to tune the cavities capacitively or a combination of inductive and. capacitative tuning elements could be used. Tuning elements 17 are attached to a support ring 18 above the anodemembers 12. The support ring 18 in turn is rigidly attached to a plurality of support members or rods 19 which extend upwardly through apertures 20 in the upper magnetic pole piece 21 of the magnetron which is hermetically sealed to the anode ring 11. Support members 19, which may be, for example, solid metallic rods, after passing through upper pole piece 21 are embedded in a guide member 22, which is slidably mounted in a cylinder 23, cylinder 23 in turn being rigidly attached through a flanged member 24 to a cylindrical case member 25 surrounding cylinder 23 and hermetically sealed to upper magnetic pole piece 21. A flexible her- Inetic seal is provided between the movable guide member 22 and the flanged member 24 by means of a bellows 26, surrounding cylinder 23.

In order to prevent energy in the magnetron anode structure from feeding through the apertures 20, through which the support members or rods 19 pass, there are provided toroidal springs 27 surrounding each of the support members 19. The toroidal springs are positioned in recesses in the magnetic pole piece cut down from the upper surface thereof surrounding the apertures 20. The springs 27 are held in place by retaining cylinders 28, which are pushed into the recesses containing the springs 27 above the springs 27. In order to insure a resilient contact between the members 19 and the springs 27, the inner diameter of the springs 27 in their normal position is somewhat smaller than the diameter of the members 19. Since the coils 27 produce an electrical short between the support members 19 and the upper magnetic pole piece 21, energy is prevented from passing through pole piece 21 and hence undesirable resonances which might occur from the dimensions of the space surrounding the bellows 26 are prevented from interfering with the operation of the magnetron.

Referring now to Fig. 3, there is shown another embodiment of this invention. Fig. 3 discloses an anode structure 10 similar to that shown in Figs. 1 and 2. However, instead of having the tuning elements 17 of Figs. 1 and 2 attached to a support ring, the tuning elements in Fig. 3 are part of the support rods as indicated at 29. Each of the rods 29 has a toroidal coil 30 surrounding it in resilient contact therewith as it passes through the pole piece 21. The coils 30 are similar to the coils 27 shown in Figs. 1 and 2 and are held in place by similar retaining cylinders 31. By positioning the distance of the coils 30 sufliciently far above the anode members 12, the resonance produced by the electrical circuit comprising adjacent tuner elements may be adjusted to any desired frequency remote from the operating frequency of the device, thereby eliminating interference from tuner resonances. In addition, resonances which might occur in the region above the upper pole piece 21 are prevented from being coupled through the apertures in pole piece 21 through which the rods 29 pass, thereby preventing their interference with the operation of the device.

This completes the description of the embodiments of the invention illustrated herein. However, it is to be clearly understood that many modifications thereof will be apparent to persons skilled without departing from the spirit and scope of this invention. For example, the

resilient contacting member could be used in slidable shorting devices other than magnetron tuners and the slidable tuner with the shorting member could be used in other devices than magnetrons, for example, klystrons.

Accordingly, it is desired this invention be not limited to the particular details of the embodiments disclosed herein except as defined by the appended claims.

What is claimed is:

1. An electron discharge device comprising an evacuated envelope including an anode structure and a pair of oppositely disposed magnetic pole pieces, said anode structure including a plurality of anode members, a cathode spaced from said anode members, tuning means positioned adjacent said anode structure, a support member attached to said tuning means and movable with respect to said anode structure, and a resilient conducting member consisting of a toroidal spring surrounding said support member and in resilient contact with said support member and one of said pole pieces.

2. An electron discharge device comprising a cathode, an anode spaced from said cathode, tuning means positioned adjacent said anode, a plurality of support members attached to said tuning means and movable with respect to said anode, and a resilient conducting member consisting of a toroidal spring surrounding and in resilient contact with each of said support members.

3. An electron discharge device comprising a cathode, an anode structure spaced from said cathode, means including a pair of oppositely disposed pole pieces attached to said anode for producing a magnetic field in the space between said anode structure and said cathode in a direction substantially transverse to the electron paths,

tuning means positioned adjacent said anode structure, a plurality of support members attached to said tuning means and movable With respect to said anode structure, and a resilient conducting member consisting of a toroidal spring surrounding each of said support members and in resilient contact with each of said support members and one of said pole pieces.

4. An electron discharge device comprising a cathode, an anode spaced from said cathode, means for producing a magnetic field in the space between said anode and said cathode in a direction substantially transverse to the electron paths, tuning means positioned adjacent said anode, a plurality of support members attached to said tuning means and movable with respect to said anode, and a resilient conducting member consisting of a toroidal spring surrounding and in resilient contact with each of said support members, said resilient conducting member being substantially fixed with respect to said anode.

5. A cavity resonator, tuning means for said cavity resonator movably positioned adjacent said resonator, a support member attached to said tuning means and movable with respect to said resonator, and a resilient conducting member consisting of a toroidal spring surrounding and in resilient contact with said support member.

References Cited in the file of this patent UNITED STATES PATENTS