US2407707A - Electron discharge device - Google Patents

Description

Sept. 17, 1946. G, R, vKlLGQRE 2,407,707

ELECTRON DISCHARGE DEVICE Filed April 24, 1942 lNvEN G/efzarye Patented Sept. 17, 1946 ELECTRON DISCHARGE DEVICE George Ross Kilgore, Verona, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application April 24, 1942, Serial No. 440,299

(Cl. Z50-27.5)

19 Claims.

My invention relates to electron discharge devices, more particularly to such devices utilizing beam deflection and suitable for use at ultra high frequencies.

In tubes of the type under consideration a beam of electrons is directed between a pair of deecting electrodes toward an apertured electrode behind which is usually placed a collector. Alternating voltages are applied to the deiiecting electrodes to cause the electron beam to be deilected across the aperture to thus control the amount of current flowing to the collector which may be used as an output electrode. In such types of tubes the deflection sensitivity drops oi as the frequency at which the tube is operated is increased. Eforts have been made to increase the defiection sensitivity or the transconductance of the tube, but such efforts have not met with a great deal of success.

Conventional tubes are also subject to the limitation that, when operated at ultra high frequencies, the input circuit tends to be of low resonant impedance resulting in an excessive amount oi power being required to drive the tube. This decreases the effective power gain of the tube when operated as an amplifier. Fundamental causes of low resonant impedance include, among other things, radiation and resistance losses due to high circulating current in electrodes and leads. Electron loading also results from the inter-action of the electron stream and the circuits connected to the tube and includes degenerative and regenerative eiects caused by common lead impedances.

It is an object of my invention to provide an electron discharge device of the beam deflection type which is particularly suitable for use at high frequencies and which has a comparatively high transconductance.

It is another object of my invention to provide such a device utilizing an input circuit having high resonant impedance, thus making more effective use of the driving power.

A further object of my invention is to provide such a device in which undesired coupling, due to common leads and ineliective shielding, is reduced to a minimum.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a longitudinal schematic section of one form of an electron discharge device made according to my invention and its associated circuit, Figure 2 is a section taken along the line 2-2 of Figure 1 and Figure 3 is a longitudinal schematic section of the device shown in Figure 1.

Referring' to Figure 1, an electron discharge device made according to my invention comprises an evacuated envelope l0 containing at one end a cathode II and at the other end a collector I2 for receiving electrons generated by cathode Il. Next adjacent to the cathode is a beam forming and shielding cup-shaped member I3 provided with an aperture I3 through which the beam of electrons is directed between a pair of rod electrodes I E and I5 for determining the direction of the beam through the various electrodes, the proper biasing voltages being supplied by means of voltage source I6 in the form of a voltage source and potentiometer arrangement. Positioned between the collector and the beam forming member I3 is a resonant cavity tank circuit or cavity resonator comprising a tubular memberV I1 closed at one end by means of the member I8 and provided with aperture I 8 registering with the beam directed from the cathode II. A cone-shaped partition I 9 provided with aperture I9' is positioned intermediate the ends of the member I'I to provide between the closing member I8 and partition I9 a resonantl cavity. The other end of the tubular member I 'l is closed by means of the member 20 provided with tubular inwardly extending member 2| in which the co1- lector I2 is positioned and by which it is shielded and screened from the field within the resonant' cavity. The chamber formed between the partition I9 and closure member 20 provides an. output resonant cavity which is set and maintained in oscillation, in a manner now well understood, when groups of electrons pass across the gap 2|'. It is obvious that this second resonant cavity or output resonant cavity tank circuit could be eliminated and the collector utilized as an `output electrode, the output circuit being connected to this electrode.

In accordance with my invention I provide between the apertured disc member I8 and partition I9 a pair of deflecting electrodes 22 and 23 supported by means of the strip supporting members 22 and 23', these electrodes deflecting the beam `of electrons across aperture I9 during operation of the electron discharge device.

The surface of member I'I is provided with an aperture I'I into which the reentrant portion I0 of envelope I0 extends and into which an input coupling loop 24 extends to excite the resonator during operation of the device; Another aperture Il" is provided in the output resonant cavity tank circuit into which a second reentrant portion EQ of the envelope I5 extends to permit a coupling loop 25 to be extended within the cavity to lbe coupled withthe radio frequency field generated within the cavity. A source of voltage 26 is provided from which the various biasing voltages may be obtained.

In operation a beam of electrons is formed by means of cathode II and beam forming andy shielding electrode I3, the direction of the beam being easily controlled by means of the directing electrodes I4 and l5. The beam is directed through aperture I3', between deilecting electrodes 22 and 23 which in one mode of operation of the resonant cavity tank circuit between the end member I8 and partition I9, produces a deflecting voltage across the electrodes 22v and 23. As a result the electron beam is deflected across the aperture IS inducing a radio frequency voltage in the output cavity between partitions I9 and closure member 2E! when :the groups of electrons pass across gap 2l and are collected by collector I2, which is thoroughly shielded by means of the reentrant tubular member 2 I The deflecting electrodes 22 and 23 have, preferably, a length equal to approximately the distance travelled by an electron` during a half period of the natural frequency of oscillation of the input rescnant cavity tank circuit formed between closure member I8 and the partition I9. I have found this produces a maximum deflection sensitivity for this kind of operation. l

Figure 3 shows a schematic longitudinal section of a lmodification of my invention. In this embodiment a cathodey 3l)y is provided with a heater 3l positioned at one end ofthe device and collector 32 is positioned at the other end of the device, this collector also servingas an output electrode. Next adjacent the cathode is a cylindrical beam forming and directing member 33, preferably in the form of a tubular member closed at both ends by means of apertured disc membersl33 and 33". Within the tubular member 33` but insulated therefrom are beam directing electrodes 34 and 35, which derive their potential from the voltage source 35. Positioned between the beam forming member 33 and col-V lector 32 is a resonant cavity tank circuit or cavity resonator 31 in the form of an annularY hollowv member of conducting material. Mounted on opposite. walls are delecting electrodes 3S and 39 between whichv thek beam is directed to be deflected across the closure member 40 provided with an aperture bisected by member 45, thus giving a double aperture and providing certain desirable characteristics. Tubular extensions 4@ and 4I extending outwardly from the cavity are provided with cup-shaped elements 42 and 43, which are sealedv to the insulating cupshaped members 44 and 45 for supporting the inputy and collector electrodes and providing with the resonant cavity an evacuated envelope. An aperture 41 is provided in the resonant cavity 3l. The aperture is surrounded by collar 48 to which is sealed a reentrant insulating cup-shaped member is into which the input coupling loop 5i) extends for exciting the resonant cavity. The out. put voltage is impressed on the output transformer 5I and the various biasing voltages are taken from the source 52.

In operation the beam of electrons from cathode 39 is properly directed through various apertures by means of electrodes 34 and 35 and the` electrons are accelerated through the apertured closure member 45 and between the deflecting' electrodes 38 and 39 between which appears a deiiecting radio frequency voltage, it being und'erstod in the usual mode of operation that the radio frequency currents circulate from electrode (is around 'the inside of the tank to the other electrode 3B, the magnetic field lying perpendicular to the radio frequency voltage and currents in a manner now well known.

Thus in both arrangements a high transconductance results since the length of the deilecting electrodes bears a definite relationship to the operating input frequency. Because of the enclosed circuit utilized the losses are reduced substantially, thus making more power available for dri-ving the input circuit and the tube. Because of the enclosed circuits and because of `the large shielding mass between the input and output circuits, undesired coupling is reduced to a minimum so that the device lends itself particularly to use as an amplifier, although it is Suitable for use as an oscillator with smalll changes provid'- ng feedback.

While I have indicated the preferred embodi ments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means. limited to the exact forms illustrated or the use indicated, but that many variations may be made in theparticular structure used and thepurposefor which it is employed without departing from the scope of my invention as set forth in the appended'claims.

What I claim as new is:

l. An electron discharge device having 'a cathode for supplying a beam of electrons, a collectorfor said electrons, a cavity resonator for containing an electromagnetic field having a resonant frequency and positioned between said cathode and said collector, said cavity resonator havingV an opening in the wall thereof through which said beam of electrons is to be directed, oppo-` sitely disposed deecting electrodes positioned within said cavity resonator toY lie within said electromagnetic field and between which said beam of electrons passes during operation of said electron discharge device, each of said deecting electrodes being separate from and supported by and electrically connected to a different portion oi the inside wall of said resonator, said resonator having a second opening in. another part of its wall aligned with said first opening and across which said beam of electrons is deflected by said deflecting electrodes during operation of said electron discharge device.

2. An electron discharge device having cathode means for supplying a beam of electrons, a cavity resonator for containing an electromagnetic eld and positioned adjacent said cathode means and having oppositely disposed apertures in opposite walls thereof through which the beam of electrons is to be directed, and'. a pair ofi defiecting elements separatevfrom the wall of said cavity resonator within the cavity resonator positioned next adjacent said apertures and connected to the inside walls of said cavity resonator to lie within said electromagnetic field and between which said beam of electrons is to be directed to be deflected thereby, and an output electrode system including a member having a pair of apertures through which the beamA of electrons is alternately directed during operation of said electron discharge device.

3. An electron discharge device including a amavo? cathode means for providing a beam of electrons and receiving means for said electrons, and other means positioned between said cathodemeans and said-receiving means for deecting said electron beam and including a closed hollow conducting member for containing an electromagnetic iield having apertures in diierent portions of the wall thereof through which the electron beam is to be directed, and oppositely disposed deiiecting electrodes separate from the wall of said closed hollow conducting member within said enclosed hollow conducting member between which said beam passes, each of said deflecting electrodes being supported from and electrically coupled to a diiierent Vpart of the inside wall of said enclosed conducting member to lie within said electromagnetic eld, and means positioned between said receiving means and said deecting electrodes and having a pair of adjacent apertures across which said beam is to be deflected.

4; An electron discharge device including cathode means for providing a beam of electrons, and receiving means for receiving said electrons, and other means positioned between said cathode means and said receiving means for deiiecting said electron beam, and including a hollow conducting member for containing an electromagnetic field and having registering apertures in opposite walls thereof through which said beam of electrons is to be directed, and a deflecting electrode positioned within said hollow conducting member and electrically connected to the inside wall of said hollow conducting member next adjacent one aperture, and another deecting electrode positioned within said hollow conducting member and electrically connected to the inside wall of the conducting member next adjacent the registering aperture, said deflecting electrodes being separate from the walls of said hollow conducting member and oppositely disposed within fsaid hollow conducting member to lie within said electromagnetic field the path of said beam lying between said deiiecting electrodes, and a member positioned between the deecting electrodes and the receiving means and having an aperture across which said beam is to be deected.

5. An electron discharge device including cathode means for providing a beam of electrons, and receiving means for said beam of electrons, a cavity resonator for containing an electromagnetic field and positioned between said cathode means and receiving means and having registering apertures in opposite walls thereof through which said beam is to be directed, and deflecting electrodes independent of the wall of the cavity resonator positioned within said cavity resonator, said deiiecting electrodes being oppositely disposed, one of the deflecting electrodes being electrically connected to the inside wall of the cavity resonator next adjacent one aperture, and another deiiecting electrode being connected to the inside wall of the cavity resonator next adjacent the other aperture, said deecting electrodes being within said resonator to lie within said electromagnetic field, and means provided with an aperture across which said beam is to be deiiectedand positioned between the receiving means andthe defiecting electrodes.

6. An electron discharge device including cathode means for providing a beam of electrons, and receiving means for said beam of electrons, a cavity resonator for containing an electromagnetic eld and positioned between said cathode means and receiving means and having regis-i tering apertures in opposite walls thereof through which said beam is to be directed, and deflecting electrodes separate from the walls of said cavity resonator positioned within said cavity resonator to lie within said electromagnetic field, said deecting electrodes being oppositely disposed, one of the deflecting electrodes being electrically connected to the inside wall of the cavity resonator next adjacent one aperture, and another deecting electrode being connected to the inside wall of the cavity resonator next adjacent the other aperture, and means positioned between the receiving means and said deflecting electrodes and having a pair of adjacent apertures across which said beam is to be deiiected.

'7. An electron discharge device having cathode means for supplying a beam of electrons and a collector for receiving said electrons, and means positioned between the cathode means and collector and including a cavity resonator for` containing an electromagnetic iield having registering apertures disposed in opposite walls thereof through which said beam is to be directed, and

a pair of delecting electrodes separate from the wall of said cavity resonator and positioned intermediate said apertures within said resonator to lie within said electromagnetic field and on opposite sides of the beam path directed therethrough, and supporting and conducting means connected between said deflecting electrodes and the inside wall of the hollow conducting member intermediate the apertures.

8. An electron discharge device having cathode means for supplying a beam of electrons and a collector for receiving said electrons, and means positioned between the cathode means and collector and including a first cavity resonator for containing an electromagnetic field and having registering apertures disposed in opposite walls thereof through which said beam is to be directed, and a pair of deflecting electrodes separate from the walls of said cavity resonator positioned intermediate said apertures within said resonator to lie within said field and on opposite sides of the path of the beam directed therethrough, and supportingand conducting means connected between said deecting electrodes and to the inside wall of the first cavity resonator intermediate the apertures, and a second cavity resonator positioned between said rst cavity resonator and said collecting means and through which said beam is to be directed.

9. An electron discharge device having cathode means for providing a beam of electrons, a collector for receiving said beam of electrons, and a pair of adjacent cavity resonators each for conningan electromagnetic field and .positioned between .the cathode means and collector and having a plurality of aligned apertures through which the electron beam is directed, deecting electrodes separate from and positioned within the rst cavity resonator to lie within the electromagnetic field and through which the beam path passes and between which therbeam is to be direoted for deiiecting .the electron beam across an aperture between the cavity resonators, said defiecting electrodes being supported by means of conducting strips connected to the inside wall of the first of said cavity resonators intermedi-ate the apertures of the rst cavity resonator.

10. An electron discharge device having cathode means for providing a beam of electrons, a collector for receiving said beam of electrons, and a pair `of adjacent cavity resonators positioned between the cathode means and collector andl having a plurality of aligned apertures through which the electron beam issto be directed, deflect--l ing electrodes positioned within the rst cavity resonator through which the beam path passes and between which the beam is .to be directedfor. deecting the electron .beam across anA aperture between the -cavity lresonators, said delecting electrodes being supported by means of conducting strips connected to the innerV wall of the. rst of said cavity resonators intermediate the apertures of .the first cavity resonator, said second cavity resonator being provided with a reentrant portion having an opening registeringA with the apertures, said collector being positioned within said reentrant portion.

11. An electron discharge device having a cathode for supplying electrons, a collector for said electrons, a tubular member positioned between said cathode and said collector and having aclosuremember at each end thereof, and a partition intermediate said closure members, said closure members and said partition being provided with aligned apertures, a pair of deflecting electrodes positioned between a closure member adjacent said cathode and said partition and comprising a pair of oppositely disposed elements parallel to lthe beam path and strap-like elements supporting and electrically connecting said deecting electrodes from the inner wall of the tubular member intermediate said last closure member and said partition, a` reentrant tubular member extending from the closure member adjacent said collector and providing with said partition a gap across which the beam path of electrons passes.

l2. An electron discharge device having a cathode for supplying electrons, and means adjacent said cathode for forming said electrons into a beam, a collector for said electrons, a tubular member positioned between the beam forming means and said collector and having a closure ymember ateach end thereof', and a partition intermediate said closure members thereby forming two successive cavity resonators, said closure members and said partition being provided with aligned apertures, a pair of deecting electrodes positioned between the closure member adjacent .the beam forming means and said partition and comprising a pair of oppositely disposed elements parallel to the beam path and strap-like elements supporting and electrically connecting said delecting electrodes with the inner wall of the tubular member intermediate said last closure member and said partition, a reentrant tubular member extending from the closure member adjacent said collector and providing with said partition a gap across which the beam path of electrons passes, the rst cavity resonator having an aperture into which an input coupling loop may be extended, and the second cavity resonator having another aperture into which an outputcou'- pling loop may be extended.

13. An electron discharge device havingrazcathode for supplying electrons, and means adjacent said cathode for forming said electrons into a beam, and a collector for saidelectrons, a tubular member positioned between 1the beam vfor-ming means and said collector and having a closure member at each end thereof, and a partition intermediate said closure members thereby-forming two successive cavity resonators, said closure members and said partition being provided `with .aligned apertures, a pair of deflectingI electrodes positioned between the closure member adjacent the beam forming means andsaid partition and comprising. a pair of oppositelyL disposed elements parallel to the,A beam'path and strap-like elements supporting and electrically connecting said deflecting electrodeswith the inner wall of the` tubular member intermediate said last closure member and said partition, a reentrant .tubular member extending fromy the closure member adjacent said collector and; providing with said partition a gap across` which the beam path of electrons passes, Said, collectorl being positioned Within said reentrant .tubular member, and beam directing electrodes positioned within the beam forming means for directing the beam through the apertures in the partition and closure members during, operation. of' said electron discharge device.

ifi. An'electron discharge devicev having a cath- 0de for Supplying. electrons and a collector for said electrons, means including a cavity' resonator positioned between the cathode, and collector and having aperturas in opposite Walls thereof, a deiiecting electrode extending inwardly of said Cavity resonator and positioned adjacent one aperture and an oppositely disposed deiiectingV electrode positioned adjacent the other aperture, outwardly extending tubular extensions around said apertures and each; provided with an apertured closure member through which the: beam of, electrons tobe directed. 'i

15. An electron. discharge device having. a cathode for supplying electrons and a collector for said electrons means including a cavity res'- onator positionedv between the cathode andv co1- lector and having apertures in oppositeV walls thereof,` a denecting electrode extending inwardly of said cavity resonator and positionedv adjacent` one aperture and an oppositely disposed deflecting electrode positioned, adjacent the other aperture, outwardly extending tubular extensions around said apertures and each provided with an aperturedy closure member 'through which the beam of electrons is to be directed', and a beam forming and directing meansv positioned between the cathode and one of the apertured closure members, and including a hollow conducting member and a pair of beamV directing electrodes.

16. An electron discharge device having a. cathode for supplying electrons and a collector for said electrons, means including a cavity resonator positioned between` the cathode andfcollector andY having apertures in opposite walls thereof, a deilecting electrode extending inwardlyV of said cavity` resonator and positioned adjacent one aperture and an oppositely disposed delecting electrode positioned adjacent the other aperture, outwardly extending tubular extensions around said apertures and each provided with an apertured closure member through which the beam of electrons is to be directed, and cup-shaped members sealed to said tubular extensions on said cavity resonator and forming with said cavity resonator an envelope for the cathode and collector electrode.

1'7'. An electron discharge device having a cathode for supplying electrons. and a collector for said electrons, means including a cavity resonator positioned between the cathode and collector and; having apertures in opposite walls thereof, a deflecting electrode extending inwardly of said cavityresonatorand positioned adjacent one aperture and an oppositely disposed deflecting elec trode positioned;adjacentthe; other aperture, outwardly-extending tubular exten-sions around said apertures, each extension having an apertured closure member'throughWhichthe beam oit elec.- trons is tot be directed, and cup-shaped members sealed to said tubular extensions on said cavity resonator and forming with said cavity resonator an envelope for the cathode and collector electrode, and a third aperture in said cavity resonator and a reentrant cup-shaped member sealing said aperture, said last cup-shaped member being adapted to receive a coupling loop within said aperture.

18. An electron discharge device having a cathode for supplying a stream of electrons and a collector for said electrons, a cavity resonator positioned between the cathode and collector and having apertures in opposite walls thereof, a deiiecting electrode extending inwardly of said cavity resonator from the wall thereof and adjacent one of said apertures, and a second deflecting electrode positioned opposite the first and supported by and from the wall of the cavity resonator adjacent the other aperture, outwardly extending tubular extensions surrounding said apertures each having an apertured closure member at the free end thereof, cup-shaped flange extensions secured to said tubular members and closure members sealed to said flange members and providing with said cavity resonator an envelope, and beam forming and directing means positioned between the cathode and collector and having apertures in opposite walls thereof, a deecting electrode extending inwardly of said cavity resonator from the wall thereof and adjacent one of said apertures, and a second deflecting electrode positioned opposite the irst and supported by and from the wall of the cavity resonator adjacent the other aperture, outwardly extending tubular extensions surrounding said apertures and having apertured closure members at the ends thereof, cup-shaped flange members secured to said tubular extensions and closure members sealed to said flange members and providing with said cavity resonator an envelope, and beam forming and directing means positioned between said cathode and one of the tubular extensions of said cavity resonator, the closure member adjacent said collector having a double aperture.

GEORGE ROSS KJLGORE.

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