US2452056A

US2452056A - Electrical discharge device

Info

Publication number: US2452056A
Application number: US545768A
Authority: US
Inventors: Kather Erich Nevin
Original assignee: Raytheon Manufacturing Co
Current assignee: Raytheon Co
Priority date: 1944-07-20
Filing date: 1944-07-20
Publication date: 1948-10-26
Anticipated expiration: 1965-10-26

Description

Oct. 26, 1948. KATHER ELECTRICAL DISCHARGE DEVICE 2 Sheets-Sheet 1 Filed July 20, 1944 /r If! I m I11 I r Oct. 26, 1948. E. N. KATHER 1 2,452,056

' ELECTRICAL DISCHARGE DEVICE Filed July 20, 1944 2 Sheets-Sheet 2 Patented Oct. 26, 1948 2,452,056 ELECTRICAL DISCHARGE DEVICE Erich Nevin Kather, South Lincoln, Mass, as-

signor to Raytheon Manufacturing Company, Newton, Mass, a corporation of Delaware Application July 20, 1944, Serial No. 545,768

Claims. 1

This invention relates to an electron discharge tube of the type adapted to generate ultra high frequency oscillations, and more particularly to one in which the frequency of one or more resonant circuits within the tube determines the fre quency of the oscillations produced.

In such devices it is frequently desirable to vary, within limits, the frequency of the oscillations generated by the tube.

It is among the objects of this invention to provide a novel and eificient means for varying the frequency of the oscillations generated by the tube while the tube is in operation. In such devices various factors beyond the control of the operator may alter the frequency at which the tube is resonant. For example. a change in the operating temperature may alter the resonant frequency.

A further object of the invention is to provide a means for varying the frequency of the oscillations generated by the tube which will also function as a frequency stabilizer .to maintain the oscillations generated at the desired adjusted frequency regardless of changes in the operating 7 conditions.

The above and other objects of the invention will be fully set forth in the following detailed description, taken in conjunction with the accompanying drawings in which:

Fig. 1 shows a transverse section through a magnetron constructed in accordance with my invention;

Fig. 2 shows a section taken on line 2-2 of Fig. l; and

Fig. 3 shows a partial side elevation, partial section taken on line 3-3 of Fig. 2.

Referring to the drawings, there is shown a magnetron comprising a block I of conductive material, such as copper. A plurality of anode arms 2 project radially from the interior surface of the block I providing therebetween a plurality of resonant cavities 3.

Hollow end sections

4 and 5 covered by end caps 6 and I are provided at each end of the block I. A cathode 8 is provided centrally of block I adjacent the inner ends of the anode arms 2 and is supported by lead-in conductors 9 and I ll extending through the

hollow end sections

4 and 5. Lead-in conductors 9 and III are sealed in glass seals I I and I2 mounted at the outer ends of conductive pipes l3 and I I, respectively. The conductive pipes I3 and [4 are hermetically secured within the wall of the block I adjacent the

end sections

4 and 5. Within one of the resonant cavities 3 is a coupling loop I5 having one end connected to a lead wire IS. The

lead wire I6 is sea-led through a glass seal II mounted at the outer end of a conductive pi-pe I8 hermetically secured within the wall of the block I. The other end of the coupling loop I5 is secured to the inner end of the conductive pipe I8. Magnetic poles l9 and 20 are provided adjacent the end caps 6 and I to create a magnetic field extending longitudinally of the device.

When such devices are energized, oscillations are set up from which energy may be derived by the coupling loop I5 and led out of the tube by lead wire I6 and conductive pipe I8 which constitute a coaxial transmission line. On the exterior of the tube the high frequency oscillations may be conducted to any suitable utilization circuit by a continuation of the concentric line or any other transmission line in a manner known in the art.

In the operation of such devices a capacity exists between the cathode 8 and the face of each of the anode arms 2. Also capacitances exist between the side walls of adjacent anode arms 2. The interior walls of the resonant cavities 3 constitute inductances. The anode is so designed and spaced relative to the cathode that the capacitances and inductances described constitute circuits which are tuned. The construction so fai described is such that these circuits are resonant at a predetermined frequency depending upon the geometry of the tube. The device is intended to operate so that each cavity 3 forms a circuit tuned to the frequency at which each of the other cavities 3 oscillates.

In order to vary the frequencies of the oscillations generated by the tube, I provide a coupling loop 2| extending into the end sectioni closely adjacent to one end of one of the cavities 3. One end of the loop 2| is connected to the inner end of an outer tubular conductor 22 of a section of coaxial line 23 having an inner conductor 24. The other end of the loop 2| is connected to said inner conductor 24. The outer end of the coaxial line 23 is closed and the line is supported near its inner ends by a flexible diaphragm 25, which diaphragm has a central opening through which the outer tubular conductor extends and in which it is hermetically sealed. The diaphragm 25 is soldered or otherwise integrally connected along its peripheral edge to therim of a cup-shaped member 21, the joint constitutin an hermetic seal. The cup-shaped member 21 is mounted upon one end of the block I, a portionof the block I being cut away for this purpose, and the cupshaped member soldered or otherwise secured to the side wall of the block I in a manner to secure an hermetic seal therewith. An elongated opening 28 is provided in the base of the cup-shaped member through which a reduced end 29 of the outer tubular conductor 22 extends. The dimensions of the elongated opening 28 are such that the inner end 29 of the outertubular conductor 22 may be moved upwardly and downwardly within the opening.

The length of the coaxial line 23 is fixed to give a predetermined reactance as determined by the tube and load characteristics. This length is such that the coaxial line is approximately resonant at the operating wave length but nevertheless; ofi to one side at resonance. The length may be taken either side of resonance dependingon the tube and load characteristics, in the one case the reactance of the coaxial line will be inductive and in the other case its reactance willxbe capacitive. In either case the line 23 constitutes a reactance coupled in the oscillatory circuit of the tube by the loop 2|. By applying pressure to the outer end-.of the coaxial line 23,'the coupling loop 2| may be moved relative to the resonant cavity 3, the diaphragm 25 flexing for this purpose, so that the loop-will be'closer toor farther from the oscillatory field of thislcavity and therebythe coupling between the coaxial line and the resonant cavity. may be varied. An increase in coupling caused bymoving the'loop 2| closer to the rasonantcavity 3: increases the amount of the reaotance: coupled in the. oscillatory circuit. Movement of the loop in this direction changes the-frequency at which: thecircuitprovided by the "system is resonant; Byamoving the loop farthenfromi the. cavity, the coupling therebetween is decreasedand-ithe. resonant frequency of the system is accordingly changed. Breferably therratioof the inner diameter of the outer tubular'conductor to the outer diameter ohtheijinnenconductor ismade equal to 3.6. In other wordsv these parts are dimensioned to prov-ide:a1high Q and? since the. coaxial line is approximately resonant at the operating wave lengthbut neverthelessoff to one side at resonance, that-istheresonantirequency of the eoax-iab line is slightly: different from the resonant frequency-of the system, the line will tend to pull the system back totheadjusted frequency wheneventhe systemtends to vary from the predetermined frequency. Thusthe device provides both atuning= means and a'means for stabilizing the frequency'of the. system.

From the above description it will be seen that th'elnventi'on providesanovel and eflicient means f onvaryingawithin limits. the frequencies of the oscillations'generated by the tube at the will of theoperator while. the tube is in operation. Furthermore, where the inductively coupled line is made approximately resonant at the operating wave lengthof the.tube but nevertheless off to one side at resonance, the invention provides a frequency stabilizing. effect at the adjusted frequency;

While there has been herein described an illustrativeembodiment oi the invention, other embodiments within the scope of the appended claimszwill beapparent to those skilled in the art from a consideration of the embodiment shownand the-teachings hereof. For example, the-invention maybe applied to tubes of the type having a resonant cavity determining the frequency of the oscillations produced other than the specific -mag-netron shown. The-coupling loop may be made adjustable relative to the resonant cavity by--means other than the specific means shown-and the circuit prltividing'the reactance connected to the adjustable coupling need not necessarily be a coaxial line.

What is claimed is:

1. A magnetron comprising: an evacuated envelope, electrode elements within said envelope providing a resonant circuit, a coaxial line having one end thereof opening into said envelope and the other end thereof hermetically sealed, a coupling loop coupling said coaxial line to said resonant circuit, and means carried by said envelope and adjustably supporting said coaxial line to enable-the movement of said coupling loop relative to said resonant circuit to vary the inductive coupling therebetween.

2. 'A magnetron comprising: an evacuated envelope, electrode elements within said envelope providing a resonant circuit, a. coaxial line including an outer tubular conductor and an inner coaxial conductor, one end of said outer tubular conductor opening into said envelope and the othenend; thereof being hermetically sealed, a coupling. loop connected at one end to said outer tubularconductor andat its opposite end to said inner conductor and extending into said envelope coupling said coaxial line to said resonant circuit, and means carried-by said envelope and adjustably supporting said coaxial lineto enable the movement thereof to thereby movesaid coupling loop relative to said resonantcircuit to vary the inductive coupling therebetween.

3. A magnetron comprising: an evacuated en-v velope, electrode elements within said envelope providing a resonant circuit, a coaxial line including an outer tubular conductor and an inner coaxial conductor, one endof said outer tubular conductor opening into said envelope and the other end thereof being hermetically sealed, a coupling loop connected at one'end to said outer tubular conductor and at its oppqsite end to said inner conductor and extending into said envelope coupling said coaxial line to said resonant circuit, said coaxial line being movably mounted and hermetically sealed in a wall of said envelope wherebysaid coupling loop is. movable relative to said resonant circuit to vary the inductive. coupling therebetweem 4. A magnetron comprising: an evacuated envelope, electrode elements within said envelope providing a resonant circuit, a coaxial linehaving one end thereofopening into said envelope and the other end thereof hermeticallysealed, said coaxial line being approximately tuned to the frequency ot'said resonant circuit, a coupling loop coupling said coaxial line to said resonant circuit, and means carried by said envelope and adjustably supporting said coaxial lineto enable the movement of said coupling loop relative to saidresonant circuit to vary the inductive coupling therebetween.

5; A- magnetron comprising: an evacuated envelope; electrode elements within said envelope providing a, resonant circuit, a coaxial line including an outer tubular conductor and an inner coaxial conductor, one end of said outer tubular conductor opening into said envelope and the other end thereof being hermetically sealed, a coupling loop connected; at one end to said outer tubular conductor and at its-opposite end to said inner conductorand extending into said envelope couplingsaid coaxial line to said resonant circuit, saidcoaxial line being approximately tuned to the frequency of said resonant circuit and movably mounted and hermetically sealed in a wall of said envelope to thereby enable the movement of said coupling loop relative to said resonant circuit to vary the inductive coupling therebetween.

6. An electron discharge device comprising: an evacuated enveloped, electrode elements within said envelope providing a resonant circuit, a circuit separate from said electrode elements providing a reactance, a coupling loop carried by said reactance circuit and extending into said envelope, in spaced relationship to said resonant circuit, for inductively coupling said resonant and reactance circuits, and means carried by said envelope and adjustably supporting said reactance circuit to enable variation of the spacing between said coupling loop and said resonant circuit for varying the coupling therebetween.

7. An electron discharge device comprising: an evacuated envelope, electrode elements within said envelope providing a resonant circuit, a circuit separate from said electrode elements approximately tuned to the frequency of said resonant circuit and providing a reactance, a coupling loop carried by said reactance circuit and extending into said envelope, in spaced relationship to said resonant circuit, for inductively coupling said resonant and reactance circuits, and means carried by said envelope and adjustably supporting said reactance circuit to enable variation of the spacing between said coupling loop and said resonant circuit for varying the coupling therebetween.

8. An electron discharge device comprising: an evacuated envelope, electrode elements within said envelope providing a resonant circuit, a coaxial line having one end thereof opening into said envelope and approximately tuned to the frequency of said resonant circuit but off to one side at resonance providing a reactance, a coupling loop carried by said coaxial line and extending into said envelope, in spaced relationship to said resonant circuit for inductively coupling said resonant circuit and said coaxial line, and means carried by said envelope and adjustably supporting said coaxial line to enable variation of the spacing between said coupling loop and said resonant circuit for varying the coupling therebetween.

9. An electron discharge device comprising: an evacuated envelope, electrode elements within said envelope providing a resonant circuit, a coaxial line having one end opening into said envelope and the other end hermetically sealed and approximately tuned to the frequency of said resonant circuit but off to one side at resonance providing a reactance, a coupling loop inductively coupling said resonant circuit and said coaxial line, a flexible diaphragm mounted in a wall of said envelope and hermetically sealed therewith, said coaxial line being sealed in an opening through said diaphragm whereby movements of said line vary the spacing between said coupling loop and said resonant circuit for varying the coupling therebetween.

ERICH NEVIN KATHER.

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

UNITED STATES PATENTS Number Name Date 2,233,166 Hahn Feb. 25, 1941 2,242,249 Varian et a1. May 20, 1941 2,243,537 Ryan May 27, 1941 2,304,186 Litton Dec. 8, 1942 2,311,520 Clifford Feb. 16, 1943 2,348,986 Linder May 16, 1944 2,404,086 Okress July 16, 1946 2,404,279 Dow July 16, 1946 2,408,235 Spencer Sept. 24, 1946