US3173054A

US3173054A - High frequency electric discharge devices

Info

Publication number: US3173054A
Application number: US93894A
Authority: US
Inventors: Baker John Edwin
Original assignee: MO Valve Co Ltd
Current assignee: MO Valve Co Ltd
Priority date: 1960-03-10
Filing date: 1961-03-07
Publication date: 1965-03-09
Anticipated expiration: 1982-03-09
Also published as: GB917681A

Description

March 9, 1965 J. E. BAKER 3,173,054

HIGH FREQUENCY ELECTRIC DISCHARGE DEVICES Filed- March 7, 1961 2 Sheets-Sheet 1 my 0R (AH/V Mul an-R 1y f 42%, am: 1 1

March 9, 1965 Filed March 7, 1961 J. E. BAKER 3,173,054

HIGH FREQUENCY ELECTRIC DISCHARGE DEVICES 2 Sheets-Sheet 2 Fig. 2

I N VEN FUR ANN 6WM/ 319M571 BY- 40414, am. 15

United States Patent 3,173,054 HIGH FREQUENCY ELECTRIC DISCHARGE DEVICES John Edwin Baker, Walthamstow, London, England, as-

signor to The M-() Valve Company Limited, London, England Filed Mar. 7, 1961, Ser. No. 93,894 Claims priority, application Great Britain, Mar. 10, 1960, 8,567 60 4 Claims. (Cl. SIS-39.53)

This invention relates to high frequency electric discharge devices of the kind having a high frequency connector in the form of a pair of coaxial conductors the inner of which is sealed through a member of electrically insulating material which forms part of the envelope of the device.

It is sometimes desirable to couple such a connector to an external feeder in the form of a coaxial line. If in such a case the ends of conductors of the coaxial line are directly coupled in operation to the conductors of the relevant high frequency connector, there may be a risk of damage to the seal of the inner conductor of the connector, for example, due to vibration of the coaxial line. Such damage is especially liable to occur with high power devices where it is desirable that the line should be of rigid construction.

It is an object of the present invention to provide a high frequency electric discharge device of the kind specified, in which the connector may be coupled to a feeder in the form of a coaxial line without incurring the above mentioned risk.

According to the invention, a high frequency electric discharge device of the kind specified has associated with it a cavity resonator situated external to the envelope of the device and rigidly fixed with respect to the envelope with a part of the wall of the resonator adjacent the seal of the inner conductor of the connector, the wall of the resonator being electrically coupled to the outer conductor of the connector, the inner conductor of the connector extending into the resonator through an aperture in said part of the wall of the resonator, and the resonator being provided with means for coupling to it one end of an external feeder in the form of a coaxial line.

One arrangement in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a part-sectional side elevation of a vane type magnetron employing double ring strapping; and

FIGURE 2 is a sectional elevation along the line II-Il in FIGURE 1;

Referring to the drawings, the electrode structure of the magnetron is housed within a sealed metal envelope 1 comprising a number of coaxial tubular portions of dillerent diameters arranged end to end, the portion 2 of the largest diameter constituting part of the anode of the magnetron.

The anode further includes eight vanes 3, each of which is in the form of a thin rectangular metal plate, the vanes 3 being housed within the portion 2 and being symmetrically disposed around the axis of the mag netron, in planes containing the axis of the magnetron, with their lon er edges parallel to the axis of the magnetron. At their outer longer edges the vanes 3 fit in slots formed in the inner surface of the portion 2 and the inner longer edges of the vanes 3 lie adjacent a cylindrical cathode 4 housed coaxially within the anode.

The vanes 3 are strapped together by means of two metal rings 5 and 6 of different diameters disposed coaxially within the portion 2 in a plane substantially coincident with one set of shorter edges of the vanes 3,

"ice

slots 7 being cut in the vanes 3 so that each ring 5 or 6 connects together a different set of alternate ones of the vanes 3. The vanes 3 are similarly strapped together by means of two similar rings (not visible in the drawings) disposed coaxially within the portion 2 in a plane substantially coincident with the other set of shorter edges of the vanes 3, but here the larger ring connects together the vanes which at the other end of the anode are connected together by the smaller ring 6 and vice versa.

Power is extracted from the magnetron via an output connector 8 in the form of a pair of coaxial conductors extending radially from the anode of the magnetron. The outer conductor of the connector 8 is constituted partly by a substantially frustro-conical copper block 9 and partly by a short length of copper tubing 10, the block 9 being brazed at its narrower end to the portion 2 and having an axial aperture 11 extending into it from its smaller face which communicates with a corresponding aperture 12 in the wall of the portion 2. The tubing 10 is sealed coaxially into an aperture 13 which extends axially into the block 9 from its larger face and which communicates at about the centre of the block 9 with the aperture 11, the aperture 13 being of larger diameter than the aperture 11. At its end remote from the anode, the tubing 10 opens into a short portion 14 of larger diameter than the portion sealed into the aperture 13, and into this portion 14 is sealed a ceramic disc 15; the block 9, the tubing 10 and the disc 15 thus all form part of the envelope 1 of the magnetron. The inner conductor of the connector 8 is'constituted by a. copper conductor 16 which is secured at one end to the strapping ring 5, passes axially through the

apertures

11, 12 and 13 and the tubing 10, passes through a seal in the disc 15 and terminates in a probe 17.

The magnetron is secured to a metal block 18, described below in greater detail, by means of bolts 19 which pass through holes provided in a flange 20 at the wider end of the block 9 and through corresponding holes in a flange 21 provided at the end of the portion 14 of the tubing 10, the flange 21 being trapped between the block 18 and tubular spacers 22, the spacers 22 serving to hold the block 9 away from the block 18.

The magnetic field required for operation of the magnetron is provided by a permanent magnet constituted by a tubular member 23 having a longitudinally extending slit; a pair of fiat rings 24 which fit respectively in contact with the ends of the tubular member 23 and a pair of hollow substantially frustro-conical members 25 which fit coaxially within the tubular member 23. The magnet is disposed with the tubular member 23 coaxially surrounding the magnetron and the narrower ends of the members 25 locating on coaxial portions 26 of the envelope 1 adjacent the portion 2 in which are housed pole pieces for the magnet (not visible in the drawings). The slit in the member 23 is positioned so as to accommodate the block 9 which itself is partly cut away to enable it to fit in the slit.

The magnetron and magnet assembly are housed within a protective casing 27 which is secured to the block 18, leads (not visible in the drawings) to the electrodes of the magnetron being brought out through an opening 28 in the casing 27. The space within the casing 27 not occupied by the magnetron and the magnet assembly is filled with silicone rubber 29, the rubber 29 being injected into the casing 27 in a liquid state via the opening 28 which is plugged with thermosetting resin loaded with silica flour 30 when the rubber 29 has hardened.

The block 18 has formed in it a rectangular cavity 31 of dimensions such as to be resonant approximately at the frequency of the oscillation produced by the magnetron. The probe 17 extends into the cavity 31 via a circular aperture 32 formed in the wall of the cavity 31 adjacent the ceramic disc 15, and a similar aperture 33 is formed in the opposite wall of the cavity 31, the aperture 33 being coaxially surrounded by'a circular choke slot arrangement 34 formed in the face of the block 18, the slot being filled with a suitable dielectric material. The cavity 31 is tunable by means of a slug 35 which screws into a tapped aperture in a side wall of the cavity 31.

In operation of the magnetron, power from the magnetron is fed to the cavity 31 via the connector 8 and power may be supplied from the cavity 31 to a load via an external coaxial line (not shown) whose outer conductor is secured to the main face of the block 18 remote from the magnetron, and whose inner conductor terminates in a probe which extends into the cavity 31 via the aperture 33. Clearly, there is little risk of vibration causing damage to the seal via which the inner conductor of the connector 8 passes through the envelope 1. In addition, the cavity 31 acts as a tuned transformer which enables impedance matching between the load and the magnetron to be obtained.

In the arrangement described above, by way of example, the discharge device has only one high frequency connector and has associated with it only one cavity resonator. In other arrangements in accordance with the invention, for example, where the discharge device is an amplifying device, the discharge device may have more than one high frequency connector and have associated with it more than one cavity resonator.

I claim:

1. In combination, for use with an external feeder in the form of a coaxial line:

a high frequency electric discharge device having a sealed envelope and having a high frequency connector in the form of a pair of coaxial conductors, the outer conductor being constituted by a generally tubular rigid metallic member which projects outwardly from the main body of the envelope and itself forms part of the envelope and the inner conductor being sealed through a member of insulating material which is sealed across the interior of the outer conductor adjacent its outer end and which also forms part of the envelope, the inner conductor having a portion projecting beyond the outer end of the outer conductor;

a cavity resonator situated external to the envelope of the device, the resonator having an aperture in its wall;

means rigidly clamping said outer conductor to the wall of the resonator with the outer end of the outer conductor in contact with the exterior of the wall of the resonator around said aperture and with said portion of the inner conductor extending into the resonator through said aperture;

and means for coupling the resonator to one end of said external feeder.

2. The combination according to claim 1, in which the discharge device and said clamping means are disposed within a rigid housing which is partly constituted by a portion of the wall of the resonator, the remaining space within the housing being substantially filled with a resilient packing material.

3. The combination according to claim 1, including means to vary the resonant frequency of the resonator.

4. In combination, for use with an external feeder in the form of a coaxial line:

a high frequency electric discharge device having a sealed envelope and having a high frequency connector in the form of a pair of coaxial conductors, the outer conductor being constituted by a generally tubular rigid metallic member which projects outwardly from the main body of the envelope and itself forms parts of the envelope and the inner conductor being sealed through a member of insulating material which is sealed across the interior of the outer conductor adjacent its outer end and which also forms part of the envelope, the inner conductor having a portion projecting beyond the outer end of the outer conductor, and the outer conductor having an outwardly extending flange at its outer end;

means rigidly clamping said outer conductor to the wall of the resonator with said flange in contact with the exterior of the wall of the resonator around said aperture and with said portion of the inner conductor extending into the resonator through said aperture;

a rigid housing which is partly constituted by a portion of the wall of the resonator and within which the discharge device and said clamping means are disposed, the remaining space within the housing being substantially filled with a resilient packing material;

and means for coupling the resonator to one end of said external feeder.

References Cited by the Examiner UNITED STATES PATENTS 2,283,895 5/42 Mouromtseif et al. 333-83 X 2,603,711 7/52 Woodyard 33383 2,657,314 10/53 Kleen et al. 315-393 X 2,820,127 1/58 Argento et al 333-83 X DAVID J. GALVIN, Primary Examin r.

ARTHUR GAUSS, GEORGE N. WESTBY, Examiners.

Claims

1. IN COMBINATION, FOR USE WITH AN EXTERNAL FEEDER IN THE FORM OF A COAXIAL LINE: A HIGH FREQUENCY ELECTRIC DISCHARGE DEVICE HAVING A SEALED ENVELOPE AND HAVING A HIGH FREQUENCY CONNECTOR IN THE FORM OF A PAIR OF COAXIAL CONDUCTORS, THE OUTER CONDUCTOR BEING CONSTITUTED BY A GENERALLY TUBULAR RIGID METALLIC MEMBER WHICH PROJECTS OUTWARDLY FROM THE MAIN BODY OF THE ENVELOPE AND ITSELF FORMS PART OF THE ENVELOPE AND THE INNER CONDUCTOR BEING SEALED THROUGH A MEMBER OF INSULATING MATERIAL WHICH IS SEALED ACROS THE INTERIOR OF THE OUTER CONDUCTOR ADJACENT ITS OUTER END AND WHICH ALSO FORMS PART OF THE ENVELOPE, THE INNER CONDUCTOR HAVING AN PORTION PROJECTING BEYOND THE OUTER END OF THE OUTER CONDUCTOR; A CAVITY RESONATOR SITUATED EXTERNAL TO THE ENVELOPE OF THE DEVICE, THE RESONATOR HAVING AN APERTURE IN ITS WALL;