US2479084A - Directed beam high-frequency oscillator - Google Patents

Description

Aug. 16, 1949. A. H. ROSENTHAL 2,479,084

' DIRECTED BEAM HIGH-FREQUENCY OSCILLATOR Filed April 28, 1945 I 104 INVENTOR. v 106 105 4004 PH x205 ENTHAL y L97 4 %y 925 Arrow/5 3 between the pulses no energy is abstracted from the passing electron stream since its electron density is at a minimum. In practice, and due to the fact that the beam current is not absolutely zero between successive groupings, a certain though small amount of oscillatory energy is abstracted from the load by the passing electron beam and by acceleration of its electrons, reconverted into kinetic energy. Thereby, and because only during each second half cycle energy is added to the load circuit, the maximum output of the device is limited and an element of asym metry introduced in the generation of the oscillations. e

According to the invention; a considerable increase and particularly doublingof the output of electronic devices utilizing transit time phenomena in electron beams or streams is obtained and energy supplied to the load circuit or resonator in each half cycle of the oscillation cycle or period. Referring again to Fig. 1, according to the invention energy is supplied not only during the half waves or pulses H], II, etc.; in addition thereto and in opposite direction, 1. e., at a phase displacement of about 180 with respect to the pulses [0, ll, etc., energy is supplied also during the half waves or pulses l4, l5, I6,etc., indicated by dotted lines.

According to the invention, two streams or beams of electrons are caused to pass closely an 1 energy abstracting portion of the load or resonator, preferably an energy abstracting gap, in essentially opposite directions, and grouping or bunching of the electrons is caused in those beams at a phase displacement approximating 180 or one half cycle. Referring again to Fig. 1, energy will be abstracted from successive electron groups in one beam passing the load in one direction during part of one half cycle of each oscillation period so that voltage half waves or pulses I0, I I, [2, etc., are produced in the load, whereas by the successive electron groups in the other stream of essentially opposite direction voltage half waves or pulses l4, 15, etc., of opposite sign are produced in the same load. The groupings in the two beams are displaced relative to one another in phase at about 180 and the alternation or oscillating electric field across the gap always opposes each electron group'passing therethrough so as to decelerate the grouped electrons and abstract energy therefrom. Thereby energy is supplied to the load or resonator during each half cycle of its oscillations, and ap- According to the invention two electron beams of essentially opposite directions are causedto bunch within the same space wherein a great portion of their kinetic energy is abstracted and which therefore can be regarded as the space or area of the phase-focus for both electron beams. For practical reasons it is desirable to produce within that space not only the phasefoci of the two beams, but also to focus them angularly into that space, i. e. to cause a convergence of the two electron streams at this energy abstracting space or area which therefore should be made the locus for four foci, i. e., two phase-foci and two angular foci. Whilst phasefocusing can be obtained as a result of transit time phenomena, angular focusing can be obtained by well known electron-optical means, e. g.

70 :the respective beam, and are connected with a substantially imaging the electron 'emitters'or restricted cross sections" of the electron beams 4 in front of the emitters (so-called cross-overs) by electron lens systems upon the space or area of the angular focus. Such electron lens systems may be either purely electro-static and consist e. g. of a number of cylindrical electrodes on suitable D. C. potentials and surrounding each beam, or of magnetic design and consist e. g. of suitably shaped permanent or electro-magnets. Since the decelerated electrons of the beams outgoing from the energy abstracting space or area must be collected, the not yet decelerated electrons of one beam entering that space or area from one side are to be separated from the decelerated electrons outgoing from that space or area in essentially opposite direction. According to the invention, the latter electrons are deflected from the path of the entering electrons and directed to suitable collectors either magnetically or utilizing the difference in average velocity of the incoming and outgoing beams of substantially opposite directions.

Separation by magnetic deflection can be effected by passing the beams through a constant magnetic field which deflects the electrons traversing it in opposite directions clock-wise and anti-clock-wise, respectively. This is illustrated in Figures 2 and 3.

Referring to Figs. 2 and 3, an electron tube is exemplified comprising an evacuated envelope [1, for instance of glass, and electron guns at opposite ends !8, IS. The electron guns comprise, for instance, thermionic electron emitters 20, 2|, such as fiat cathodes wh ich'are heated by heating elements 22, 23 traversed by an adjustable electric heating current from a suitable source (not shown). Electron optical means of any conventional type can be used for concentrating and angularly focusing the electron streams; in this exemplification of the invention and for simplicitys sake, only concentrating elements 24, 25 are shown, usually at the same potential with the emitters 20, 2 I. The electron streams 26, 21 continuously emerging from the emitters 20, 2| pass through current intensity controlling or modulating fields produced by proper electromagnetic or electrostatic means. Control electrodes or grids 2B, 29 are arranged for this purpose in the path of each beam26, 21 and impress electric signals representative, e. g., of intelligence upon the beam, or modulate its intensity in any impulse frequency other than the carrier or fundamental frequency to be produced or generated. Such signals or impulse frequencies are usually derived from an external source, in particular of alternating voltage, not shown. Steady biasing potentials are applied respectively between electrode 28 and cathode 20, and between electrode 29 and cathode 2i, and those biasing potentials are preferably adjustable, either independently or for the same amounts, for instance,,by mechanically coupling the handles for adjusting them. If no intensity modulation of the'beam or beams by extraneous signals or impulses is intended, electrode 28 and/or 29, or electromagnetic equivalents thereof, can be omitted.

Pairs of grids 30, 3| and 32, 33 or like buncher electrodes are arranged in the paths of electron beams 26 and 21, respectively, for velocity modulation in well known manner of the electrons in source of alternating modulating voltage, not shown, in such a manner that the velocity modulations in beams 26 and 21 are displaced in phase by'180.

Two pairs of magnetic fields cross the paths amazes-4 c pairofofluxesl36a3kin xthezopposite direction. is 5 indicated bya a sign within: dottedtcircles:

indicating 1 the aapproximate: positions; .of: these, 1

fieldslw Considering .first thei effect of. those: fields :HDOILL:

beams. 26 :in which the.'.:ve10cities.'.of. successive l0 electronsiemergingLfromncathQde 2flu=idiffer due to;

their .czelocity; modulation, magnetic flllXa or. fieldzfii 342M111 efiectia deflectionof all electronsand also,.

anangularresolutionof. the-electrons of. different 1;;

velocitiesircomprisedaby beam'..26.a:;:Electrons;.-.of 1

lower velocity are angularlydeflectedto a greaterd."

extent-than. electrons; of. greater velocity, and-J consequently siast electrons... follow; bath; 1238;;

whereas slow. electrons; follow; path .46; thereby thezelectrons comprised. by .beam 26 are.. some-.

what spreader .Whenthey pass .thesecondmaga 4 netic=field36 of opposite ;dir.ection,..again an .angu:

larrdefiection-uof electrons-of -.difierent-velocities-.

is efi-ectedobutin opposite; direction than ,by the.

first magnetic field 3A. The slower electrons-care 11 3810f theifaster..electronsais bent topath Aland; path-'MMof/the:slowemelectrons :bent to .pathrM whereby the angular resolution of the electrons...

of .difierentwelocities:eifeeted by =field'. 34;.1's fully compensatedmiByzsuitableaspacing of .theimagetn netiefields,34.and-.36: oftpropenstrengthsfrom one 1 another. and thevelocity-modulating .electrodesa 30; s3|;ei=. e.,sby proper:.ldimensioningof .the drift;

path;iofntheielectrons it can .be arranged ,that .35

the;slow-enand;, iaster; electronswf .beam; 2.63am. 1".

angularly randephaseafocused;fltogdesired extent uponiandlgroupedat the pointn or area 45; with ineorsin' thezyicinity. of a circumierentialugapee theepointi or. area i 45 swilliproducer byrinductionl. =1

a roltageopulsegssucnasrlfi; :Figtel, in thezaresonatoroso -.thata oscillations rate-the ;frequency;. of

in resonator. d9iandsbuild up 1 the: aoscillatory; en n ergyrtherein; 1

The; ,thu decelerated outgoing. electrons .of a beam. fine-continue their nightrin :the same; direct-1;: tion; awhich theyeentered .the; electllioufield or 1 areani5,earelsomewh-atrdesfocused .aandig-etzout M115 tance iromsthezothe'r electron beam-'2..1t:that1no .v,; substantial deflectioneor .deiocusing of. the latter-111,1

result -gt.- l

The electrons of -the*--oppositely directed:..beam. .12 l are velocity modulated by :the buncher .elece w trodes nor-grids i 32, 33am the sameway as .the. electrons-[of beam 26;:-rthe iphases of -the.velocity...-.. modulation of-Jthewbeams. 26 1andj2l are. opposite;: howeuer il. e. displaced at. ananglenof. about..180..;-

.Again the electrons..of-.beam;.2l are deflected bya-l.

the :magnetie field 35;;the fastest r electrons '-.leas t..i.-.: and. their initial-path is bent to path 39,:;'where-.1; as the slowest electronszcomprised by :beam-.21:are.-. deflected =most. by fillX35 .to travel along path 4| :2'

The thus -.somewhatnde-focused .or spreading.

beam z-2'linow passesthe magneticfield 31 ofope posite directionithanfield -35iand, therefore, path: 4|l-j0fnitSS1OW8St electrons is deflected most; to a pathcMgz: while .path...3 9::of the-fastest .electronsis deflected. least ;to: path" 42.1w: As ea result-,iazthe spreading 1 of the electrons 01". different velocities comprised .bybeam;21 is again .compensatedandra they-are :focused. in point :or area ressentiall'y'i; theisame at. whichtheielectrons of beam 26;'had.-;:: been focused previously: In'the' same way-as de-L scribed .hereinbeforesfor' beams. 26,:. the ;.elec.tr.ons.- of different velocities thus angularly zfocused; are. also brought in. phase focus .or concentratedintori. groups or bunchesflatarea45.? However. due,=tO.. the phasedispla'cement of about 180 between the. velocity modulation of...the oppositely directed. beams 26, .21, the groupings orv ,bunchings .occur .1 in them alternately at placeA5-within gap 46 and. do not interfere with one-another. Thedirece. tion-of ,thejelectriefield;across gap 46.,also alter..- natesat the velocity; modulation frequency of thebeams and ina phase so as to oppose each. group of concentratedcharges formed in beams...v 26 andril andtoabstract alternately energ from themduring 'eachhalf-gcycle of theoscillae; tions in resonator .49.= 7

Outgoing decelerated electrons; of beam:2| pass. 5-: magneticgfieldy36,:eand againj fastest electrons. thoughof decelerated linear velocity are deflected leastalong pathqfid andslowesaelectrons of. re-

du ced linearvelocity are-deflected mostalong pathZ;53.- A oollecting; electrode'could be -ar. ranged in their paththe same as electrode 52.in; thet'path of the idecelerated outgoing electrons of beam-T26.' According;:t0 1a modification of the invention shown in Fig-5 3, the decelerated electrons. of beam 21;.deflected;by.magnetic field 36, are directed into a neck of tubeenvelope i'lxin; whicha collectorelectrode 56 is arranged, preferably at the same positive potential as'that of electrode-5'2;v Thereby not onlythepaths of the incoming electrons of :beam26 and of the outgoing g"; electrons-of beam--21 are separated, but any influence of electroden521upon beam 26 is eliminated. it should TbE understood by anyone skilled in -the :art that the above effects can :be secured-n byproper;arrangementpf the place where field acts upon the electron beams, and by adjusting its strength.-

Difierent types andarrangements of c011ecting:- electrodes 52 "and' 56 have 'heen shown in Fig. 3 for convenience sake. In practice it will be preferred to use collecting electrodes of equal type,.. i. e. allorthem either-of the type 52 or the type 56,":or of course of any; other suitable type or hap 7 Between collector electrodes ,52 :and.56;onone hand; and electron emitters or cathodes 2.0;.121 "on theziother. hand a suitablerzsource of steady. 1pc: r tential; ;rdifierenceii(not showmis .arrangedntherm positive side'at the collector electrodes and the beam is effected by deflecting their paths in different or opposite directions by means of a magnetic field crossing both paths. The degrees of angular resolution exerted upon electrons of dif- :ferent linear velocities of each beam are different, and these electrons are therefore caused to diverge or spread somewhat. While this is not detrimental for outgoing electrons which can be caught by an electrode of sufiiciently large surface, it might be undesirable with respect to incoming electrons if they are to be focused sharply in point or area 45. However, the velocity modulated electrons come into phase after their travel over the drift path, and if therefore'gap 46 and the restricted electric field crossing it are properly shaped, grouping within that field can be accomplished and utilized even without sharp angular focus, and the magnetic fields 34, can be omitted. In such case, however, electron streams 26, 21 should not be emitted in axial direction and essentially perpendicular to a plane through gap 46, but obliquely to that axis. For instance, the

tube extensions containing the electron guns and other electrodes could be arranged in directions of the average beams 38, 40 and 39, 4!, respectively. The electrons emerging from the cathode should also in such case be focused by electron optical means upon area upon passing separating field 36 they would be deflected and spread angularly, again the fastest electrons least and the slowest electrons most, and a somewhat de focused and spreading beam rather than a converging beam 42, 44 would travel toward space or area 45 of tube l'i within gap 46. By proper -dimensioning of the strength of field 36, of the angle at which velocity modulated electrons enter that field and of their drift path, it can be obtained that the incoming electrons of different linear velocities are grouped and in phase when they pass that area 45 of tube IT. The outgoing decelerated electrons will then enter magnetic field 31 and, due to its identical direction with field 36, be deflected in the same direction once again but to a greater degree because of their reduced linear velocities, toward and finally be attracted by the collector electrode 52. The same, of course, applies to beam 21 flowing in opposite direction in the absence of field 35.

In order to eliminate such spreading and thereby defocusing of the respective beams by the separating magnetic fields 36, 31, the magnetic fields 34, 35 are provided in the respective paths of the two beams with the effects described hereinbefore, viz. to somewhat de-focus each beam before it enters the separating magnetic fields 36, 31 which, because of their opposite direction to fields 35, 36, in addition to their separating action effect angular re-focusing of the respective beam upon area 45. Whereas magnetic fields 36, 31 separate in all events the incoming and out-'- going electrons of the oppositely travelling beams, fields 34, 35 compensate the otherwise resulting de-focusing action of the separating fields 36,31 upon the incoming beams and may therefore be termed compensating fields.

Whether separating deflecting magnetic fields are used only or compensating magnetic fields in addition thereto, it will be appreciated that by the J qualities resulting from their relatively high invention it is obtained that concentrated or' grouped electron charges are passing alternately and in opposite direction essentially the same restricted space within the tube in such phases that useful energy can be abstracted from them, and because the frequency of these alternating passages equals that of the tuned load, abstracted energy is added each time to oscillatory power in that load in each half wave of the oscillations.

The compensating and separating fields can be produced at the proper places either bypermanent magnets or in the manner exemplified in Fig. 2. Two curved electro- magnet cores 51, 58 are arranged on one side and counter pieces 59, 60 on the opposite side of and with their suitably shaped pole faces as close as possible to envelope l'l. Magnetising coils 6|, 6| are arranged on cores 57, 58, preferably in series with one another and a source of current 62 and a resistor 53; by moving tap 64 along resistor 63 the magnitude of the exciting current passing coils 6| can be adjusted and thereby the strength of the magnetic fields produced by them. If so desired, pieces 59, 68 can also be provided with magnetizing coils.

Useful oscillatory power can be derived from resonator or load 49 in well known manner, for instance, by loops and concentric conductors 65, 66.

Whereas in the just described embodiment of the invention the two electron beams are separated by deflecting them magnetically in different directions, the embodiment shown in Fig. 4 effects such separation by utilizing the different average velocities of the incoming and outgoing electron beams. Since the outgoing beam upon traversing space or area 45 has translated a great part :of its kinetic energy to the oscillating circuit, the average velocity of its electrons is considerably lower than that of the oppositely entering velocity modulated beam. Therefore an electrode of suitably adjusted potential will attract and collect the decelerated electrons of the outgoing beam, while it permits the passage of the electrons'of higher average velocity of the incoming beam. In Fig. 4 identical reference numbers indicate identical parts as shown and described herein-before with reference to Figs. 2 and 3. Oppositely directed electron streams 26, 21 are emitted by the cathodes 20, 2| heated by proper heating elements 22, 23, concentrated by electrodes 24, 25 and pass control electrodes or grids 28, 29 which control or modulate the intensity of the respective electron stream. The thus intensity modulated streams pass thereafter a pair each of velocity modulating or buncher electrodes or grids 30, 3|, and 32, 33, respectively. The thus velocity modulated electron streams pass thereafter electron optical lens systems or beam focusing devices, exemplified by magnetic fields produced by coils 61, 68 provided with casings 69, 78 of iron having narrow cylindrical gaps H, 12 facing the evacuated envelope ll of the tube, whereby magnetic fields of proper shape are produced which angularly focus the velocity modulated beams 26, 21 upon a point or area 45 within gap 46 formed between the edges 41, 48 of tanklike resonator 49, as indicated by the dash-dotted line 13, 14 for the electron beams 26, 21, respectively. By this magnetic focusing means the velocity modulated electron streams are converted into focused beams which pass through preferably cylindrical electrodes 15, I6 spacedly surrounding them. Due to their directional :9 average velocity and focusing, beams .13, 14 .;are not materially afiected loylthe positive ,potential of electrodes,l- 5, -l1-6, and group or lbunchin point or ,area; 45,,provided [the ,spacin-gs between the pairs oi buncherj electrodes andrarea 45 is such that the electrons of diff erent velocities in each nbeamicomeiin phase .fpcus. at area. or space-45 upon, passing ,the drift ,path between vthe respect.- .ti-vesbunchenve1ectrodes andlthat area orspace.

An electric {field of comparatively irestricted .volumelisiproducfed acrosslgap 46 in the manner described .hereinbefore with ,reference .to Figl 3, through which the grouped electrons of .each vfocused beam 13, .14 pass-within attraction of 'a halfrcycle of the. high frequencyenergy. or power producedin resonator, :or load- 49 at such instants that'lthis electric field. opposes the group ed. electrons .of the respective beam, ,;and I thereby detccleriates and abstracts encrgy,irom\ then1, The outgoing electronsof beam f l-3i of now relatively small-velocities :will diverge, or spread somewhat along the paths .l'l'gby she. action oi electrode-11$ vwhich;attracts and. ollects ,{Sirhilarly I the outgoing 'decteleratedelectrons of. beam 14 will diverge orspreadbehind :area, 45- along paths," 1, andgbe :attracted, andrcollccted by electrode 1-5;

The collector electrodes 15 and 16 not onlyrcollect the:decelerated. outgoingfielectrons but can also exertlintcooperation :with theother electrodes,

.suchsas cathodes lll zl and. concentrating -elec- 1 trodes :14, 25, an ,angular focusing action u upon ,the ivelocity modulated electronsY of the incoming In order 'tosecure the eflects described, it-{is .requiredlfor: .this .embodim entof the (invention in zthe ,saine way z as -.for ,lthe -one previously described with referer ice 1t Eig; 3, that grouping of the electrons ,occurs in the beam 513; 514 at a phase displacement of about 180. Sinceath-e current density or charge intensity in each stream: orbeamisa .lmimmum between-successive V ,2-6, 2fl"-;emanating ,from emitters 20 'and ll, re-

spectively, I fthe spacings of points .-8l land -z82, as well asrofpoints. and\84 equalsfor-instance a half wave ,length, .the ;same result can be robtained I e. g. by reversing theconnecti-ons 8 I, ;83 of electrodes 3 0, l with the conductors :80, L9. Resonator, .isltunedfin this example {to the velocity modulationfrequency, andIa-small I-raction .of .cth'e oscillatory energy or power produced clonductorsjfi in. the.resonator. is branched off by the loop and ,concentricbconductor.or lead ,.65.- and translated lin adprle'ferably adjustable mannerat 85 upon Wire '19 the conductive wall of resonator 49 is iccnnecteu by neanslof. lead 86 with :wire 80,:prefrerablyflin adjustable manner at .81. .-A hollow wavelgiiidej can be usedfin'stead of the Lecher system. i

'Arsource.ofrstoady currentfifl isarraneed-loee tWeentlie cathodes' zfl, 2 l andthe firstibeam concentra'ting electrodes 2I4,25 ,io n the munda e collectonfelectrodes 15, 116 onthe otherhand ,The positive terminal of source 88 is connected Joy conductors 89, 533 with .the collecting electrodes ereas, it rnegative te'rminalis connecte'dby coniictersjea e2. andQ9f3nvvith thelresp ecti-ve cathodes and" concentrating electrodes. tilt is {understood by anybody skilled in, the .art {that vthe positive potential of thecollector electrodescanhbe,lower than 7 "that of '1 accelerating "electrodes, if used; thereby, heat and otherllos ses =inycollecting the vdecelena'ted electroh sQareconsiderably reduced.

,Anot heiysource Lpf .current 34,; for .ins tanr ze5di-v tcurr ilt, haltlnglthe heating elements -I2,Z,\:23 of the cathodes is;.conn'ected with ,the former; by

,ther semen steady ,potelitial .,(not shown) ,is

' ,arranged' betweenTthelcathOdesfZO, 2 --an1dmthe negligible interierence between: the. oppositely directedlbeainsilli, .14. Y Their-same holds, ofcourse, i

iforvtherenihodiment of the inventionexemplified in:Fi..3.

In 'order .torbrin g vabout this 180 phas e dis- :placement between .the velocity. modulations of the (two streams 26,. .21 ,which :pass area .45 in counter'flow, thei'respectivegpairsof: launcher; electrodesaare .tobfe. driven by suificiently high; alternating vvoltagesat, lithe same modulationg fre- -quency but 4 at opposite phases. a To this effect,

any suitable source of high frequency scan; be.

.used. In theexemplificationlof.Fig. 4, a Lecher SYStem is iised comprisingntwoparallel conductors or wiresrldiafl. iBunche'r'electro'de 3] near- ,est fto ,ca'th'ode 20 and ,..buncher1le1ectrode 33 re- ,motest from cathode ,ZI' are connected preierably in; adjustablemanner-at 8 I ,.,82, with wire 80, *whereas ibuncher electrode: .30 remotest from conductor. 66.

Leche'r systeni, iand. thereby'the velocity, modulatin'g. electrodes 3,0,3 lg'32gandl33; itmaybersupplied by, source 418 Joy 7 connecting e'. s g'. ;.p oint 8l6i-wit h a suitable ,part of source 88 {directly or through a .potentioineter. ,Conventional means .for l adjusting that heating current arenot shown.

,If, mere. generation of oscillatcr-y highfrequency 5 .cr ultraehigh ,iregiiencyspower is vintended, the

'cam ere e troae gsszaiean be used; for-adjusting the constant power .of thoseoscillations, bymeans of La} suitable biasing. "potential applied to those electrodes, Afsmall gfraction of the zoscillato y- -:v power produced in load J19 is fed ,back through .theiLe cher system, and .therebyEself maintained oscillations-rare produced; ,useful {energy can be derived fron'i load149,e .;g through a concentric ,If mere high frequency amplification is -in- ,tended, of (incoming 'o scillatoryjenergy -of ta frequency, e. v.g'. modulated frequency the sameizas that'to-fwhichload.Ltfllisltuned, the. feed back connectionfishown can be; omitted, The incoming energy is fed; to thelLecher-system lfl, .80, driving the :hunche'relectrodes, and amplified energy is derived iromlo'a'dAS .throughlead -6 6, or many cathode '20yandbunchervele'ctrode 3,2 nearest to cathode 2| arecon'nected, preferably in adjust-- -able manner at,83,;.84,v'vith wirelfl. It points Z-8l an'd fl2, as ell,as points 8,3.,and 84, are spaced for instance b'y' a ave length and therefore of equal oscillationphase, velocity modulations pf same irequencybutfin phase opncsition areese- -cured joif theoppos'itely irectedgelectron}.strearns' other H manner,knovvngin-the-art.

I .Ii a modulation isdesired of the-highifrequency 7 power produced or generated by the above ear rangernents, which requires intensity modulation cliccntrol of the electronstreams, emanating, from thefemitters ill, 42], .the. modulating or control zvol ages. are impressed upon the control electrodes 2-9 or their equivalents arranged in those s t'reazns. impulses representative ofeany-intelli- :gence or magnitude-whatsoever, the source of which i s-.indic ate d,-schematically at F99, are trans- .latedupon the stnaams -v by connecting one terminal of that source through ,;co,nductors lim -i=0] 'be given the control electrodes 28, 29 with respect to the emitters or cathodes 20, 2|. Television, telephone, telegraph or other signals 'or impulses can be impressed upon the high frequency or ultra-high frequency power or carrier wave produced in load 49.

Detection or rectification of those signals or impulses can be combined with their amplification, e. g. by utilizing the collector current between leads 89, 90 and the positive terminal of source88.

By the use of a resonator 49 of a resonance frequency equalling a higher harmonic of the frequency in which the electron streams are velocity modulated, the device can be used as frequency multiplier. In this'case a (primary) high frequency oscillation, which may be intensity modulated by a signal, is impressed upon the velocity modulation electrodes 30, 3|, and 32, 33. The sharp voltage peaks as illustrated in Fig. 1 are, because of their sharpness, rich in high harmonics which can excite in resonator 49 strong oscillations in its resonance frequency'equalling such higher harmonic. The thus generated (secondary) oscillations of a frequency equalling a multiple of the frequency impressed upon the modulating electrodes, are also modulated in intensity by signals impressed upon the (primary) oscillations, and these intensity modulations will in general also be amplified; thus the double eifect of an amplifier and a frequency multiplier can be obtained.

It should be understood that the arrangements shown by way of exemplification in Fig. 4 for driving the buncher electrodes, generating, amplifying or modulating high or ultra-high frequency oscillations, etc., can be used for similar purposes in the embodiment shown in Fig. 3. The resonator 49 is shown in the embodiments tuned circuit can be used instead, and any other type of high frequency or ultra-high frequency circuit substituted, such as a Lecher system, hollow wave guide system, open radiator dipole, etc.,

as shown and described in more detail in my copending application Serial No. 519,130, filed January 21, 1944, now'U. S. Patent No. 2,454,094.

.The above described embodiments of themvention are of optimum effect if a 180 phase displacement between the velocity modulations of the oppositely directed'electronstreams is established by the essentially symmetrical arrangement of the various operative elements with'respect to gap 46, so as to obtain charge concentrations alternately travelling in opposite directions through the space within gap 46 or equivalent energy abstracting means. Any asymmetry in the two drift paths can be compensated by adjusting the phases of the oscillations driving the velocity modulating electrodes 30, 3| and 32, 33 of any suitable and known type so as to obtain a substantially 180 phase displacement between thesuccessive groups or bunches in the two electron streams within space 45. For instance, if the pairs of'buncher electrodes in each stream are driven at the same frequency and phase, an

asymmetric arrangement could be used and the lengths of the drift paths over which the velocity modulated electrons of the streams travel made different So that the transit time of the velocity modulated electrons for instance in stream 21 exceeds that of the velocity modulated electrons in stream 26 for an interval equalling a half period; the recurrent groupings of the electrons in stream 21 will then lag behind those in stream 25 by a half period or at a phase displacement. Thereby again the essentially symmetrical pushpull action according to the'invention is obtained by electron groups alternately passing in opposite direction the energy abstracting field space ormeans.'

It should be understood that the invention is not limited to anyexemplification 'hereinbefore described and shown in the drawing but is tofbe derived in its broadest aspects from the appended claims.

What I claim is: 1. A methodof producing electric oscillations,

Pa ularly of high or ultra-high frequency, in-

cluding the steps of developing two streams of electrons, modulating periodically the? velocities of the electrons in each stream so. that they group in theprogressing streams, directing successively in opposite directions an electron group -"formed. in one stream and an electron group formed in the other stream through a restricted space common to both electron streamswherein energy is abstracted from said electrons and their linear velocities are reduced, utilizing the'suc- Such circuit is suitably connected with or includes annular electrodes which are spaced from one another so as to form a gap 46 and are arranged outside or inside envelope l1 so that electric energy can be translated by the grouped electrons upon the electrodes in passing e. g. a decelerating electric field across that gap, by induction, or otherwise. Annular or hollow electrodes I01 substituted for rotation body or resonator 49 and arranged, e. g., inside tube- I! are indicated in dotted lines in Fig. 4; they are to be connected in conventional (and therefore not shown) manner with or form part of a tuned load circuit usually outside the tube.

cessively abstracted energies for producing electric oscillations, and collecting said decelerated electrons of each stream outside the path of the other stream and outside said space.

2. A method of producing electric oscillations, particularly of high frequency, including the steps of developing two electron streamsvelocity modulating both streams at the same frequency and at a phase displacement of about 180 so that electrons of different velocities in each stream come alternately into phase at the end of their drift path, directing successively and in opposite direction electrons of essentially same phase "at the end of their drift paths in said streams, through a restricted space common to both electron streams wherein energy is abstracted from them and their velocities are reduced, utilizing the successively abstracted energies for producing electric oscillations, and collecting .decelerated electrons of each beam outside the path of the apropos abstractions, and collecting saiddeceleratedelectrons of each stream outsideithepathiofithe other :stream and outside said-space.

4. A method of producingelectricoscillations,

particularly high or ultra-high oscillations, including the steps of developing two electron streams, velocity modulating-both streams .a'tithe same frequency to provide recurrent groups of electrons in each :progressingstream, .angularly focus'ing said groups on to substantially the same restricted space common to L-both electron streams wherein energy can the abstracted .from

said groups passing itherethrough an-d'the elecspace in opposite direction to that or saidgroups in the other focused beam and :at a phase displacement of about 180 between successive :groups passingsaid space,-collecting said decelerated electrons of each beam outgoing from-said space separately outside "the path of the other beam and outside .said space, and utilizing :the energies abstracted successively from said groups -:for producing oscillatoryenergyat the frequency iofsaidsuccessive abstractions.

5. A method of producing selectric r-oscillations, particularly high or ultra-high frequency -oscillations, including the steps of developing :two elec- 'tron streams, velocity modulating both :streams .at'the same frequency so thatygroupsioflelectrons recur in each progressing stream at :said :fre- =quency, 'focusingeach velocity :modulated stream before said grouping occurs therein and #thereafter directing itspacedly from and pasta region -of positive potential so that 'both streams at the place-Where said grouping-occurs in them are "focused and directediin opposite directions through :a restricted space common Ito :both electron :streams :Wherein energy is abstracted from each incoming groupand its electrons :are cdecelerated, timing the recurrence :of said Ffocused :groups in :both streams so that an incoming group of one jstream alternates with an incoming-groupof the other stream, utilizing the successively abstracted energies :for producing oscillatory :electr'i c :energy, and collecting the zidecelerated electrons of one stream outgoing 'from said: space =outside the :path of the incoming other stream :an'dsout-s'ide said space.

' 6. A method of producing electric :oscillations, :particularly high :or ultra-high frequency oscillations, including "the steps of developingitwo. high velocity electron streams, velocity :m'odulatin both streams at the same frequency so that groups of electrons recur in each progressing stream at said frequency, zfocusingseachzvelocity :modulated stream before said grouping occurs :therein and thereafter directing it spacedly1from and past'aregion =-of positiveipotential :which concentrates the passing electrons of relatively high velocities so that both-streams at 1 the rplace where :said grouping occurs :in them :are focused onto but enter in opposite direction a *restrictedspace common to both 8130171011StIiBfiI'HSIWhfiH-IillfihfilgY :is abstracted from each incoming ,groupzanduits {electrons:aresconsiderably deceleraterlstiming the recurrenoetof saidzfocused groupseinaboth streams so ithatsan zincoming group ;-of 1 one stream alterhates with an :incoming group :of the other stream, utilizing thesuccessively abstracted -enorgies for @producing oscillatory electric energy, and efiecting electrostatically and collecting the electrons :of relatively low'velocities of a stream 'outgo'ingfrom said space outside the pathao'f ithe incomingotherstreamand outside said space.

'37. .A :method -of producing electricoscillations, :particularly :high or ultra-high frequency oscillations, iincluding :the steps of developing two electron beams, velocity modulatin both beams at ethe-samefrequencyso that'the electrons group "recurrently in each progressing fbeam atsaid frequency, directing said beams from opposite sides through a restricted space common to both electron streams so that said groupings occur "therein, itiming' the velocity modulations of 'said beams so that their recurrent groupings alterhate, abstracting within said space energy from each group and thereby decelerating its electrons, separating on each side of said space theelectronso'f anzoutgoing beam from those o'f an-oppes'itely incomingbeam by passing them through :a magnetic 'fie'ld which deflects the outgoing electrons 'rfrom the path-ofthe incoming electrons, and collecting the thus deflected outgoing electrons outside "the path of the incoming other astreamandoutside said space.

8. A method of =produc'ingelectric oscillations, particularly high or ultra-high frequencyoscilla- 'tions,=including-the steps of developingtwoelectron streams, velocity modulating'both streams at the same "frequency so that electron groups recur -in -the pregressing' streams at said frequency, focusing and directing said streams from oppos'ites'idesdnto a res'tricted space'so that said groupings occur therein, timing the'velocitymodulations o'f saidstreams so that their recurrent groupings alternate, abstracting within said space 'energy 'from each group and thereby decelcrating its electrons, separating on each side of said space the electrons of an outgoing stream from those of an oppositely incoming stream by passing them through a separating magnetic field which deflects theoutgoin electrons from 'the path-of theincoming-electrons, collecting 'the dihus=deflected-outgoingelectrons, and =pass'ingthe electrons of an incoming focused stream through :a compensating magnetic field of opposite direction than and preceding saidseparating field,so :as to'de-"fo'cus'said incoming stream by said compensating lield and =re-focus it by said "separating 'field-onto saidspace.

i #9 A method for producing electric oscillations, particularly :of higher ultra-high frequency, 'in- :cluding the :steps of developing tWo electron "streams, velocity modulating both stream-s at 'the same trequency so-that groups-"of electrons 'recur in :each progressing stream at said frequency lzrut after different transit times, directing the groups inone stream opposite those in the other stream ithroug'h a :restricted space :common to both electron 1streams"-whe1*ein energy is abstracted from each passing group and its electrons are decellerated, phasing the velocity modulations in said streams relative to oneanotherso that'the groups in said streams -pass=altcrnately and at a phase displacement-oi about said restricted space, iutilizing said,:abstr-acted energies for producing :electric oscillatory energy, .and collecting the-dc ecelerated electrons of :each stream outside the path :of Ethe .other stream :and outside said space. '75 10. n method :for producing electric toscilla- 'tions, particularly of high or ultra-high frequency, including the steps of developing two electron streams, velocity modulating both streams at the same frequency so that groups of electrons recur in each progressing stream at said frequency, directing the groups in one stream opposite those in the other stream through a restricted space common to both electron streams wherein energy is abstracted from each passing group and its electrons are decelerated, phasing the velocity modulations in said streams relative to one another so that the groups in said streams pass alternately and at a phase displacement of about 180 said restricted space, utilizing said abstracted energies for producing electric oscillations, and collecting the decelerated electrons of each stream outside the path of the other stream and outside said space.

11. A method as set forth in claim 1, including the step of changing the intensity of at least one of said electron streams prior to its velocity modulation.

12. An electronic device for producing electric oscillations, particularly of high or ultra-high frequency, including an evacuated envelope, means for developing two electron streams in said envelope, means for velocity modulating each stream so that groups of electrons recur in each progressing stream, electron optical means for directing said streams from opposite sides through a restricted space common to both electron streams within said envelope so that said groups in each stream form in said space, energy abstracting means arranged close to said space outside the paths of said streams and groups forming therein, electrical means for driving said velocity modulating means at the same frequency and at such phase relation that said groups form alternately in said streams within said space, and electrodes outside said space and the paths of said streams toward said space for collecting the electrons of each stream outgoing from said space.

13. An electronic device and system for producing electric oscillations, particularly of high and ultra-high frequency, said device including an evacuated envelope, means for developing two electron streams in said envelope, means for velocity modulating each stream so that groups of electrons recur in each progressing stream at relatively high average velocity, electron optical means for directing said streams from opposite sides and focusing them through a restricted space common to both electron streams within said envelope so that said groups in each stream form in said space, energy abstracting means arranged close to said space outside the paths of said streams and groups forming therein, and electrodes on position potential within said envelope outside the path of each incoming focused stream arranged between said electron optical means and energy abstracting means for deflecting electrostatically and collecting the electrons of the opposite stream of relatively low average velocity outgoing from said space; said system including electrical means for driving said velocity modulating means at the same frequency and at such phase relation that said groups form alternately in said streams within said space.

14. An electronic device and system for producing electric oscillations, particularly of high and ultra-high frequency, said device including an evacuated envelope, means for developing two electron streams in said envelope, means for velocity modulatin each stream so that groups of electrons recur in each progressing stream, electron optical means for directing said streams from opposite sides and focusing them into a restricted space within said envelope so that said groups in each stream form in said space, energy abstracting means arranged close to said space outside the paths of said streams and groups forming therein, means for producing a mag netic field each at opposite sides of said restricted space crossing the paths of a stream each incoming and outgoing from said space so as to deflect the electrons of the outgoing stream from the path of the incoming stream, and electrodes Within said envelope in the path of each thus deflected outgoing stream for collecting its electrons; said system including electrical means for driving said velocity modulating means at the same frequency and at such phase relation that said groups form alternately in said streams Within said space.

15. An electronic device as set forth in claim 14, in which said collecting electrodes are spacedly arranged from the path of an incoming stream between said magnetic field and said velocity modulating means.

16. An electronic device as set forth in claim 14, in which said collecting electrodes are ar ranged within a neck-like extension of said envelope.

17. An electronic device and system for producing electric oscillations, particularly of high and ultra-high frequency, said device including an elongated evacuated envelope, means for developing two electron streams in said envelope and close to opposite ends thereof, means for velocity modulating each stream so that groups of electrons recur in each progressing stream, electron optical means for directing said streams from opposite sidesinto a restricted space within said envelope so that said groups in each stream form in said space, a pair of energy abstracting electrodes spacedly arranged from one another so as to form agap between them substantially determining said restricted space, means at opposite sides of said space for producing a separating magnetic field each across the paths of the electron streams incoming and outgoing from said space so as to deflect the electrons of the outgoing stream from the path of the incoming stream, means for producing another magnetic field across the path of each incoming stream between said separating magnetic field and said velocity modulating means, the direction of said other field opposite that of said separating field so that the electrons of different velocities of the incoming stream are de-focused and deflected in one direction by said other field and re-focused and deflected in opposite direction by said separating field, and electrodes in the path of each deflected outgoing stream for collecting its electrons; said system including electrical means for driving said velocity modulating means at the same frequency and at such phase relation that said groups form alternately in said streams within said space.

18. A system as set forth in claim 17, in which the magnetic fields of opposite direction at each side of said space are produced by means of a common electromagnet the opposite fluxes of which cross said envelope and are closed through a magnetizable counter-piece at the opposite side of said envelope.

19. An electronic device as set forth in claim 12, including a hollow conductive body forming a cavity resonator of a frequency related to that 17 of said velocity modulations, said body provided with a gap the edges of which lie in substantially parallel spaced planes essentially perpendicular to the direction of the opposite electron streams and determine substantially said restricted space. I

20. An electronic device for producing electric oscillations, particularly of high and ultra-high frequency, including an elongated evacuated envelope, an electron gun each close to the opposite ends of and within said envelope so as to develop electron streams of opposite direction, buncher electrodes in the path of each electron stream adapted to be driven so as to cause alternate bunching of the electrons in said streams within a restricted space about in the middle of said envelope, means for focusing each stream and groups forming therein into said space, a pair of energy abstracting annular electrodes spacedly arranged from one another so as to form a gap between them substantially determining said space, and a collecting electrode each in the path of a stream outgoing from said space and spaced from the path of a stream incoming to said space.

21. An electronic device as set forth in claim 12, including means for changing the intensity of at least one of said electron streams emerging from an electron gun and arranged between said gun and said velocity modulating means.

22. An electronic device as set forth in claim 12,

.1 in which said means for developing, velocity modulating and directing said streams and said collecting electrodes are arranged substantially symmetrically with respect to said restricted space.

23. An electronic device as set forth in claim 14, in which said means for developing, velocity modulating and directing said streams and said magnetic means and said collecting electrodes are arranged substantially symmetrically with respect to said restricted space.

24. An electronic device as set forth in claim 17, in which said means for developing, velocity modulating and directing said streams and said energy abstracting electrodes and said collecting electrodes and said separating magnetic means are arranged substantially symmetrically with respect to said gap.

ADOLPI-I H. ROSE'NTHAL.

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

UNITED STATES PATENTS Number Name Date 2,227,372 Webster Dec. 31, 1940 2,281,935 Hansen May 5, 1942 2,283,895 Mouromtseif May 19, 1942 2,289,319 Strobel July 7, 1942 2,317,140 Gibson Apr. 20, 1943 2,381,320 Tawney Aug. 7, 1945

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