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Publication numberUS2408437 A
Publication typeGrant
Publication dateOct 1, 1946
Filing dateOct 11, 1941
Priority dateOct 11, 1941
Publication numberUS 2408437 A, US 2408437A, US-A-2408437, US2408437 A, US2408437A
InventorsMcrae James W
Original AssigneeBell Telephone Labor Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Harmonic generating system
US 2408437 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Oct. 1, 1946.. J, W- MCRAE v2,408,437

u HARMoNIGvGENERATING SYSTEM Filled Oct. ll, 1941 Z'SheetS-Sheetl NID A TTORNE V l /NVENTOR ocr. 1, 1946. J. w. MCRAE 2,408,437v

A HARMONIC GENERATING SYSTEM Filed oct. 11, 1941 2 Sheets-Sheet 2 62 f l/VVENTOR HVJ. WMe RAE ATTORNE V Patented Oct. 1, 1,946

.UNITED .STATES PATENT orties' f y Y Y Y 2,408,437 v I I VAmimiioN-Io GENERATING s-YsTEM James W. McRae, Neptune, N, J., 'assigner to'Bell Telephone Laboratories, 'Inrpo'ratei New. York, N. Y., a corporation of NewYork Application october i1, 1941,1se`ria1Nof4-14t95 v8 Claims.

This invention relates `to 'harmonic generating or lfrequency multiplying systems and more particularly to those employing streams of charged particles, e; g., electrons, together with hollow resonators or WaveV guides especially at ultrahigh frequencies. l v Y An object of the invention is to provide i-ncreased outputs of ultra-high frequency power, at frequencies above thepractical operating limits of oscillators and amplifiers already available in the art.

A related obj ect is the efficient .transfer of power from a beam of electrically chargedparticles, e. g., electrons, to an ultra-high frequency wave or current in a transmission Eline, wave guide or the like.

Another object is to effectively excite electromagnetic .oscillations within a reson'ating chamber of very small dimensions, such as may bedesigned to resonate Iata wave-length of a few centimeters or less, by means of an electron beam or cathode ray deflectedy or rotated periodically ata frequency .relatively low compared with the reso@ nant frequency vof the chamber.

.In addition to other uses the invention may be employed to multiply the frequency of an electromagnetic wave--after it has been subjected to frequency modulation or frequency vstabilization or other process at a relatively low frequency where'the necessary techniques of the latter oper- (ci. srs-Sl ations are more readily available than at the desired final frequency.

The invention is more fully described 'hereinafter with reference to theacconpanying drawings illustrating a number of embodiments, while the scope of the invention is defined 'in the appended claims.

Inv the drawings: Y l y Fig. l shows an arrangement in which an Velectron beam swinging 'in a'plane passes through a resonating chamber during a small portionl of each cycle of the oscillation;

Fig. 2 shows an arrangement in which an elec'- tron beam is swung around continuously to describe a conicalsurface and a reaction Vb'c'etv'veen the beam and 'an associated resonator occurs -several times during' each revolution of the beam;

Fig, ZA'is an elevational View of 'the resonator in the system of Fig. 2;

`Figf is a diagram'useful in developing design formulae for the system disclosed in Fig. A2;

Fig. 4 is anelevational and'somewhat diagrammatical view of 4a resonator in the form of a `wave b'od-ying the invention;v

Fig. 5 is an enlarged cross sectional fragmental view f a wave guide such as that shown in Fig. 4; `and Fig. 6 shows .an embodiment that is in some respects a VIllodii'cat'ion of ther 'system illustrated Y in Fig.. 2`.

'Referring to Fig. 1, there is shown a vacuum tube with an .insulating air-tight envelope I U ion-'taining' an"electron gun, indicated generally at II I, andra'rilelectron intercepting electrodeor colletor I2. Ab'lock I3 of conductive material Such as copper" is shown fused into the envelope i0.' The block I3 is hollowed out to forni .an internal resonating chamber I4 with smooth, highly conductive inner walls, the space Within the' chamber communicating with the interior of the envelope I through an entrance aperture I5` andan exit 'aperture I6. The axis of the electron gun IjI 'of the collector I2 and of the apertures f5 :and 16 are arranged colinearly so that an electron beamemitte'd by the gun may be passed through the chamber I4 by way of the apertures I5 land I6 to the collector I2. A pair of deecting plates II and I8, supported in any suitable manneras by rods lextending through the yenvelope I 0, are mounted on either side of the common axis andi connected respectively to the two terininalsfof a source I9 rof, high frequency waves. A pair' ofshielding plates 20 and 2| with their 'edges separated to form a slot 2'2 are mounted on either side of the axis and both are conductively coupled to a relatively low voltage source 23 of substanti'ally constant positive biasing potential. A pair of jbeamfoc'using plates 24 and 25 Vare mounted one Von' either side ofthe axis at a position along thev course of the beam kbeyond the shielding plates 2li and 2|. vThe plates 24 and '25 are conductivelyv coupledtov the negative `terminal of a source 23. The block I3 isconductivelyc'onnected 'with a hollow conductive `pipe or wave guide Q26, the interior of which `corn'municates with the chamber I4` through a passageway 21 hollow'ed out of the block. A suitable air-tight or vacuuniseal Vis provided by a small bulb 28 or bead of 'in'sulating'A material fused to the block I3. A source 29 o'f'relatively high positive biasing potentialis connected 'between the plates 2li, v2| andthe conductive mass comprising the block I3 and Athe wave guide 26, the positive terminal of the source .2'9 being connected to the .latter system, and grounded vif desired. The collector I2 may also be connected to the system comprising the block I3-and guide26f. The heating element within the electron gun I I" may be energized in any vsui-table manner, l'as for example, by a source 30 of electromotive force connected by leads 3l and 32 to the appropriate terminals of the gun. By-pass condensers 33 and 34 may be shunted across the source I9 and the common terminal of the condensers may be connected to the lead 32 to fix the average potential of the plates I'I and I8. An electron beam controlling electrode Within the gun I I may be connected by means of a lead 35 to the positive terminal ofthe source 23 to determine the current strength of the electron beam.

In the operation of the system of Fig. 1, the electron beam is swung up and down in a vertical plane by the action of a high frequency wave impressed upon the plates II. and I8 from the source I9. Twice during each cycle of the oscillations the beam lies in the axis anda pulse or group of electrons is projected through the resonating chamber i4 by way of the aperturesV I 5 and I6. The electron pulses or groups, if properly timed, serve to sustain electromagnetic oscillations within the chamber I4, Evidently the timing will be correct if the pulses are made to arrive at intervals of an integral number of cycles of the oscillations in the chamber I4. For example, the frequency of the source I9 may be 500 megacycles per second and the beam may be made to sustain oscillations in ka suitably adjusted resonating chamber at a frequency of 10,000 megacycles per second, in which case one electron pulse traverses the chamber for every 10 complete oscillations of the iield Within the chamber.

The physical dimensions of a resonating chamber or cavity designed to oscillate in the fundamental mode at 10,000 megacycles per second or more, corresponding to 3 centimeters or less in wave-length, are necessarily very small. Furthermore, the length of the gap, designated by a as. shown in Fig. l, traversed by the electrons, must be very minute. This is because the electron transit time in the gap should be short and preferably not more than a half cycle at the resonant frequency of the chamber, or'in other words a transit angle of not over 180 degrees. If it is desired, for example, that the electrons traverse the gap in a transit angle of only 75 degrees, and if the speed of the electrons corresponds to 2400 electron volts, then for a 3 centimeter Wavelength resonator, the dimension a of the gap should not exceed about 0.025 inch. The hole through which the beam passes, the diameter of which is designated b in Fig, l, should also be small in proportion to the principal dimensions of the cavity i4. In the case of a 3 centimeter Wave-length resonator b should not much exceed 0.05 inch. If then, a beam of 0.05 inch diameter is focused to pass through the cavity with zero deflection voltage on the plates I I and I8, the application of a sinusoidal deflecting voltage to the plates will result in a short pulse of current entering the cavity at every instant of zero deflectingvoltage. The duration of this pulse should evidently be less than half a cycle of the resonant frequency of the chamber` in order that the eld -in the resonator may not return energi7 to the electrons during part of the cycle. In the example, under consideration, the time of a half cycle is` 1/20,000 microsecond. In order for the beam to cross the aperture within the period of a half cycle, the linear velocity, v, of the beam in the-ver tical direction must be given by iehes per second. .This'vehie ef @is .equal i0.

- across the aperture I5 and will be referred to hereinafter as the writing velocity of the beam, from the tracing or writing motion executed by the beam.

The required value of the velocity o together @with the frequency of the deflecting source I9 serves to determine the maximum amplitude of deflection which must be imparted to the beam.

y that of the longitudinal velocity.

For the purpose of making this calculation, the deflection of the beam in the vertical direction at the position of the aperture I5 may be represented by y-:A sin et (2) where A is the maximumamplitude to be calculated and w is 2r times the deecting frequency.

The instantaneous velocity of the beam is determined by %=Aw COS cui (3) from which it appears that the maximum writing velocity is Aw. In the numerical example under consideration It is also simple to calculate the approximate voltage required upon the plates Il and I8 to effeet an amplitude of deflection of 0.64 inch. If, for example, the distance along the axis of the tube from the deecting plates II, I8 to the aperture I5 is taken as 6A, or 3.82 inches, the lateral velocity which must be imparted to the electrons at maximum deiiection is one-sixth In the assumed case of a 2400 volt beam, the deflection may be effected by 1/36 of 2400 volts or approximately 67 volts. If desired, the amount of deiiecting voltage required may be reduced by increasing the length of the tube, and conversely, a shorter tube will require va greater deflecting voltage.

If the high energy beam were allowed to strike the block I3 during all the time except when it A =0.64 inch A was passing through the aperture I 5, only a small fraction of the total energy of the beam would be imparted to the cavity. An improvement in the efficiency of the device is secured by the use of the shielding plates 20, 2| and the focusing plates 24 and 25. The plates 20 and 2I being at a relatively low potential with respect to the cathode and serving to shield the .beam from the high potential of the source 29 impressed upon the block I3, the electron beam is in effect a low -voltage beam except during a small interval when the beam is passing through the slot 22 .between the plates 20 and 2l. Thus during most of the time that the beam is not passing through the aperture I5, it is composed of low voltage electrons'which strike one or the other of the shielding plates 20 and 2I at low velocity and with correspondingly 10W dissipation of energy. During the small fraction of the time when the beam passes through theslot 22, the electrons are accelerated longitudinally bythe highnvoltage upon arca-esc thesblock..1l3. 'Theplates 24 and '25.serve tto iocs'fthe' beam .during theiinterval vvh'enV itis passing through the .slot 22. .The spent. electrons which emerge romf'the :aperture .I6 are collected bythe collector .122. .The vultra-higll frequency wave'Y maintained .withinirthe chamber. I4 gives .rise to atraveling Wave in the Wave guide 26-fbyway oi'thercoupling .'aftordedby the passagefZljand may? be led away itoany desired pointifor utilizati'ori.

. Iln the arrangem'ent'of JEi'g. 112,' .twov .pairs 'of'..de

ectinfglplates iat 'right .angles to each other .are-

providedlatl, |18 and IT., .l8.lre'spectively.. The sou-ree 119 is connected t0 the vdeilecting' .plates through .a phase shifting .network 4D :of any known-suitable design .whiclrprovid'es'two .substantially equal voltages 2in :time l:Quadrat-,ure Plates 1.1 and 11". :are connected' together and also connected to the .cathode'andlto :the center `terniiial lof the .r'i'etvvorklLy vThe plates ,1.8 land. I8' are. connected respectively/to .the remainingk terminals lof the network 40. The block 'lf3 vfisr'eplaced lby. a somewhat Vsimilar conductive v'block IEW-.having a .hollow cavity'l vof .annularfiorm with a across sectional .sha-pe .substantially the sameas that v.of thecavity i4 :in Figfl..V Thezcavity ."Misa gure of -revolutionabout the central axis, 'which lies outside the cavity. A .series .of equally spaced entrance apertures 1H `andcorrespending exit aperturesZ vare provided, the arrangementof the apertures .4l being shown more clearly 'inFg 2A. A collector electrode l2 is provided beyondthe-exit apertures 42.

In the v'operation fof1=the arrangement of Ijig. 2, the electron beam kisgiven a 'rotating .motion by meansof the crossed electricelds maintained between 'the pairs of deflecting plates. The elec-v tron .beam generates a .conical surface, sweeping out La circular-trace 'onthe surface vof the block i3. The radius .of't'hise'ircleis `'adjusted so that the trace passes approximately through the .centers of the .entrancerapertures 4l. Inthe course of .rotation the beam sends successive 'electron pulses 'through the chamber I4 4by Way 'of the apertures 4l in rotation. Provided theiresonant frequency `of the chamber 2M is equal to :an finteger times the frequency of the source it times Y the number of. apertures, a high frequency .electromagnetic wave maybe maintained inside the cavity 'IN vand ultra-high `frec'luency:power 'deliv ered to the. associated wave vguide 26. Each exit aperture 42 is aligned with an Ventrance aperture 4.1 and 1an velement .of the .conical .surface `generated bythe beam. The minimum diameter of which the apertures M `lie, may be `determined by calculationLinra given case. Referring'to Eig. 3, let the 'diameter .of the electron beam digand the `diameter of eachV of the holes .in the v'cavity be da Then, if the ratio fof the input frequency to the `output frequency is `to be n, andfa pulse is to be delivered to the resonator foreach cycle of thetharmonic Wave, there vmust be 11. holes equally spaced .around the circumference. of .a eirclerof diameterD, where v 1 duced -out-put for fthe same holediameter be# cause-"of fthe'l-arger fraction or electrons striking the outer .-surface -oftlie resonator without yenthe circle upon tering-it. :.Itwould bed'esirable to havesthe'b'ea'm diameter much .less than thatrof thefholes, but the :use of .a ism'aller beaml kdiameter .requires a higher'fbeam currentdensityiin korder to deliver 'the same amount Yoffp'owe'r .by way vof .the beam.

Vclot-"dash radial lines.

"iTheembodiment's-of the invention .hereinabove describedfmay generally :be so designed vas 'riot-'to require .the `use 'of 'maximum Writing velocities equalto orl greater than the :velocity of flight. However, `lasthe writing velocity of 'thel beam "is not" the yvelocity :or anyimaterial body and is not mnerently :limited @to values less than the velocity o' ght,` illustrative arrangements are described hereinaiter-'which require -Writih'gV-eloci'ties greater than .the velocity. of light. 1

One such arrangement .will "be described -by us of. .a 'somewhat diagrammatic representation in Fig.. `4. t'llhe ligure representsfalength oihol'low, conductvawalled. Wave .guide V`'bent into .circular form with -aconductive radial partition 5K1l across the interior. YIf preferred, fthe length of 'wave guide vf'rriafy rstbe fclosedfat bothlends land then bentinto the formlof a circle'with thezclos'e'd ends contact, .this being the .equivalent 'for present purposes V-oila foi-remar guide a `radial partil-Jion.. The xrwave guide is assumed `to be capable of accommodating oscillations comprising .a standing Wave, l:the vwave form `of which zis represented the dottedl curve 51.. VEqually v'spaced holes `.52 similar to the 'holes "41 in the :system of i2 :are provided at the antinodal v:points fof the standing.'Wav'e configuration, there 'being of necessity a nodeat lthepa'rtition. The waveguide of-"lligg'fi .may beused 1in place .of the block 13'. intlfre-fsy`s`tem-of 2, for example. A -In the operation-.of l'a system employing a wave guide as illustrated ii-r1 Fig. 4, the standing -wave may be ysustained i-n the Wave guide by means *ofl 'a rotating electron beam entering, the guide periodically through the successive holes 52. lThe Writing velocity Yof the v'beam Jm'ust Ibe equal 'to the velocity of propagation of the wave motion 'causing the standing Wave 5I. Or, rconsideri-ng the standing iwave to -be composed of `two traveli-'ng Waves traversing the guide in `opposite direc'tions with equal Velocity, the Writing velocity ofthe beam must lequalthe phase velocityef the traveling Waves. v I A numerical example at this point will aidin the explanation as Well 'as indicate .how a systemfbased'onlig. 4 maybe designed fori-given input and youtput frequencies. 'Suppose vthat V-a Awave guide `with a' particular shape and .size iof cross sectionhas lbeen selected, -for example, the

quer-mies will be assumed, as before, to ben'500 megacycles and v110,000 megacycles per second, respectively. "The frequency-ratio being thus determined, 'the circumference Aof the circle upon which'the Valletues752 lie is accordingly .fixed at Dwave-lengths,'measured in the guide. To nd the actual'length'o'f the circumference, a knowl- 'edge' o'f 'the wave-.length vin the guide .is required, 'or of 'the zpha'se velocity in the guide., from which the Wave-.lengthis readilyvcalculated. It is known from. the theoryiof` guided wave transmission that thefphase fvelocity .in a hollow guide with con'- ductive walls isal'wa'ys .greater than thefvelocity of lightfor all finite frequencies which the guide will freely transmitand that the phase velocity approaches the velocity of;light asymptotically as the frequency isincreased. The phase velocity in a particular Wave guide will depend upon the shape and sizeof cross section' as well as upon the desired output frequency. 'The value of the phase velocity may be obtained most readily in many cases from measurements, by known methods, ,oiithe Wave-length of standing waves in a length of the actualguide. The sample upon which the measurements are madeV .may be straight and the results willrapply with sufclent approximation to the same guide bent in the form of a circle. If formulae are available for the type of guide employed it is also possible to calculate the wave-length and phase Velocity. For the purposes of the present example it will be assumed that the phase velocity in the guide is known to be 1.25 times the velocity of light. Twenty wave-lengths of a wave propagated .at 1.25 times the velocity of light evidently makel a length equal to four-fths of 20, or 16 wavelengthsof a wave propagated with the velocity oflight. V'Ihe circumference of the wave guide is, accordingly, Llicentimetersand the diameter is approximately 15.3 centimeters, or 6 inches. The number of apertures provided will be 40, that is, one foreach antinodal voltage point. In practice, the wave guide may be brought into precise resonance at a harmonic of the input frequency by tuning, as for example, by adjusting the volume of the resonant cavity by `any suitable known means.

In order to avoid loss of efficiency arising from the fact that the electrons during so large a proportion of the time strike the outside surface of the wave `guide between the holes, a continuous slot extending around the entire means circumference maybe employedinstead of theholes. Such a slot is illustrated in the wave guide shown in Fig. 5. Since the electron` beam moves along this slot with a writing velocity equal to the phase velocity in the guide, the beam will continuously enterthe guide against an opposing electric eld. That this is so may be visualized by considering againthe equivalence of the standing wave and a pair of traveling waves going in oppOsite directions. The beam keeps in -a constant phase relationshipwith the traveling wave going in the same direction, thus continually transferring energy `Vto that wave. At the partition, the traveling wave is reflected and merges with the wave traveling in the opposite direction, thereby transferring some of its energy to the other traveling wave.-

-A wave guide of the cross section illustrated in Fig.o5, approximately comprising two circular sectors, is adapted to permit the electrons to pass through the guide in a timecomparable with the periodic timeof the output frequency. For example, a-,gap of about 1/20 inch may be advantageouslyemployed with an output frequency of 10,000 megacycles. Y

. In the arrangement of Fig. 4 it is feasible to omit the partition 56 and allow the rotating beam to enterthe guide through a continuous slot. Without the partition, the guidefcan sustain a traveling wave which progresses continuously around the circumference. The `traveling wave may-be maintained by continuous abstraction of energy from the electrons, which come into the guide at a point of maximum opposing electric field. Thus the transfer of energy from vthe beam tothe electromagnetic wave in the guide is substantlally continuous. This. method of sustaining a, traveling wave in an endlesswave guide bymeans of a rotating electron beam is dis-A closed in a copending application of R. V. L. Hartley, Serial No. 385,629, led March 28, 1941,' and assigned to thev assignee of the present application.` j Y Fig. 6.shows an embodiment of the general arrangement described in connection with Fig. l with certain modifications, the system in some respects resembling that illustrated inFig. 2. vThe wave guide rvshown inFig. 6 has substantially the same cross section as the resonator in blockv I3A of Fig. 2. Instead of holes for the electron beam to entera continuous slot'is shown, the central portion of the block being supported yin any suitable manner as, for examplaby radial rodsv which cross the path of the electron beam but intercept relatively few electrons. Advantage may be taken of an arrangement disclosed in the above-cited Hartley application for increasing the circumference swept out by theelectron beam while using relatively low energizing potentials. Electrodes 60 and 6I, respectively, provide between thema conical slot through which the electron beam passes.V A steady electric field impressed between the electrodes 66 and 6I by a battery 62 or other suitable source of electromotive force, causes an outward bending of the electron beam, thereby increasing the divergence of the beam from vthe axis. Reversal of the polarity ofthe source 62 would, of course, result ina decrease inthe diameter of the circle swept out by the electron beam. A pair of electrodes 63 and ,654 separated by a circular slot may be placednear the resonator and polarized somewhat positive with respect to the conductive surface of the wave guide by a battery 65 or other suitable source of electromotive force, in order that any secondary electrons which may be emitted due to the electron beam striking any portion of thesurface of the wave guide may be attracted to and collected by the electrodes 63 and 64. The circular slots in the electrode systems 60, 6I and 63, 64 are arranged to register with the slot in the wave guide so that the electron beam may readily pass through al1 three slots.

One or both ofthe electrodes 63 and 64 may also be employed to eifectan automatic control ofthe deflection of the electron beam. For example, a resistor 66 may be inserted in series with the source 65 and the potential drop` across the resistor 86 may bearranged to subtract from `the potential difference between the electrodes 60 and 6|, the potential across the resistor partially offsetting theelectromotive force of the source 62. When the input or deflection amplitude changes, tending to throw the beam out of register'with the slot in the wave guide `and thereby tending to reduce .the current through-the cavity, the current intercepted by one or the other of the electrodes S3, 64 Ais changed, for example, in this Vcase the current to electrode 64. supposing that lthe current to the electrode Ellis increased, then the potential difference across the resistor 65 will also be increased and, accordingly, there will be a decrease in the potential difference between the electrodes 60 and 6l. The latter will tend to draw the beam closer to the axis and away from the electrode S4, thereby decreasing the current to that electrode and tending to minimize the resultant change in the deectionvof the beam.; `The control potential of the resistor 66 may beemployed, if desired, to control the amplitude'of` the yhigh frequency, input to the 9 plates l1, I8, I1' and I8 with similar effect upon the deflection of the beam. Likewise, it is feasible to employ electron current intercepted by the electrodes 6l] and 6I to secure correcting potentials which may then be applied to the electrodes I1, I8, I1 and I8' as before.

What is claimed is:

1. A harmonic generating system comprising a source of waves of given frequency, means to provide a beam of moving charged particles, a resonating chamber resonant to a harmonic of said given frequency and havingA an aperture in its wall permitting access of said beam into the interior of the chamber, means energized by said source of waves of given frequency to direct said beam into said aperture to react with an electromagnetic wave within said resonating chamber, and means to control said beam directing means to limit the phase of said reaction substantially tion and cause said beam to sweep once per cycle of the given frequency over said aperture and through an arc relatively great compared with vand including the arc subtended by said aperture at the said point of deection.

3. A harmonic generating system comprising a source of waves of a given frequency, a resonating chamber tuned to a harmonic of said given frequency and having an aperture in its wall, means to vprovide a beam of moving charged particles, and means energized by said source of waves to deflect said beam to and fro across said aperture and substantially about a, xed point of deflection once per cycle of the given frequency through an arc relatively greater compared with and including the arc subtended by said aperture at said point of deflection.

4. A harmonic generating system comprising a source of waves of a given frequency, means to provide an electron beam, a hollow resonator coaxial with said electron beam and having conductive walls and an axial'aperture, said resonator being tuned to a harmonic of said given frequency, and means energized by said source of waves of given frequency to deflect said beam to and fro across said aperture and substantially about a fixed point in the axis once per cycle of the given frequency through an arc relatively large compared with and including the arc subtended by said aperture at the said point of deflection.

5. An electron beam system comprising a cathode, means to formr an electron beam from electrons emitted by said cathode, a target containing an aperture, means to deflect said beam about a substantially fixed point of deflection through an arc relatively greater than and in- 5 cluding the arc subtended by said aperture at said point of deflection, means to impress a relatively large potential difference between said cathode and said target to accelerate electrons toward said target, means to shield said electron beam from said target throughout the major portion of the arc of deflection, said shielding means having an axial opening permitting access of the beam to the aperture in the target, and means to impress a relatively small potential difference between said cathode and said shielding means to collect electrons with low energy dissipation on said shielding means.

6. A harmonic generating system comprising a source of waves of a given frequency, a toroidalshaped resonating chamber tuned to the harmonic of said given frequency, said resonating chamber having a plurality of apertures uniformly spaced about its periphery, means to provide a beam of moving charged particles, and means energized by said source of waves of given frequency to sweep said beam over said apertures in rotation once per cycle of said given frequency, the ratio of the number of the harmonic to the number of apertures having an integral value. '7. A harmonic generating system comprising a source of waves of a given frequency, a hollow resonator with conductive walls, the cavity of which resonator is a gureof revolution about an axis outside the cavity, said resonator having a resonant frequency that is a multiple Aof the given frequency, and said resonator having a plurality of apertures communicating with the cavity of the resonator and uniformly spaced about a circle concentric with said resonator, a source of a beam of electrons, and means energized by said source of waves of given frequency for sweeping said beam f electrons over said apertures in succession at a uniform rate correlated with the -resonant frequency of said resonator to sustain ll an electromagnetic wave within the cavity of said resonator at said multiple frequency.

8. A harmonic generating system comprising a source of waves of a given frequency, a hollow conductive wave guide closed at both ends of a 50 length to support a plurality of cycles of a standing electromagnetic wave of a frequency which is a multiple of said given frequency, said wave guide being bent into circular form and provided with a plurality of apertures lying upon a circle 55 and coinciding substantially with the antinodal points of said standing wave, means to provide a beam of electrons and means synchronized with said source of waves of given frequency to sweep said electron beamfover said apertures in suc- 60 cession with a writing Velocity equal to the phase velocity of the electromagnetic wave in said wave guide.

JAMES W. MCRAE.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2418735 *Mar 23, 1943Apr 8, 1947Hartford Nat Bank & Trust CoOscillation generator including a cathode-ray tube
US2463617 *Jun 29, 1944Mar 8, 1949Bell Telephone Labor IncUltra high frequency harmonic generator
US2508346 *Jun 22, 1945May 16, 1950Gen ElectricUltra high frequency electron discharge device
US2608669 *Feb 6, 1948Aug 26, 1952Marcel WallaceCathode-ray tube wavemeter
US2668190 *Jul 5, 1947Feb 2, 1954Rca CorpTelevision image pickup system
US3219873 *Sep 1, 1961Nov 23, 1965Trw IncMicrowave electron discharge device having annular resonant cavity
US3221207 *Jun 5, 1963Nov 30, 1965Trw IncMicrowave power generating by periodic sweep of electron beam along length of resonant waveguide
US4019088 *Apr 8, 1975Apr 19, 1977Gersh Itskovich BudkerElectrovacuum SHF apparatus
US4520293 *Feb 10, 1983May 28, 1985Kernforschungszentrum Karlsruhe GmbhHigh frequency amplifier
Classifications
U.S. Classification315/5.25, 333/227, 327/123, 327/119
International ClassificationH01J25/78, H01J25/00
Cooperative ClassificationH01J25/78
European ClassificationH01J25/78