US2611882A - Electron discharge device - Google Patents

Description

P 3, 1952 R. s. BAILEY 2,611,882

ELECTRON DISCHARGE DEVICE Filed Feb. 4, 1948 W 2' W 44 Hll 1F 1, ffwmmmm 4 I I I ,IJI, W illllllbfiw I 1, E, 4'1 y x 1 11 .54 g5 g9 .so

IN VEN TOR. ROBERT 6. BAILEY ATTORNEY Patented Sept. 23, 1952 UNITED STATES P TENT 1 OFFICE I EnEc'rito'NDIsoHARGED'EvioE Roberts. -Bailey', New York; N. =Y.,- assignor'to International -Standard Electric Corporatiom-New York,-N'. Y., acorporation-of Delaware Kp'plicaticnFcBrti'ary 4, 1948; serial-Names This invention relates 'to crb'ital electron de vices and-more particularly to devices ofthe kindwherein very high frequency potentialsara in duced' in conductors or cavities respons'e to electrons moving past --the= cavity 'or conductor; Y

and ofwhichthe magnetrontube is typical;-

A principal object ofthe invention is to -pro-' vide a more efficient' orbital electron tube of i the magnetron type. I I

' Another principal object is' to provide a'n u'ltra high frequency generator of -the type employing a plurality of' cavitiesofpredeterm'ined electrophysical dimensions in conjunctionwith electioniagnetic means to develop orbit al1y-moving -'electrons which cooperate with {thecavities-whereby a greater transfer of-the electron energy int'o ultra high-frequency wave energy is obtainable.

Another objectis to provide arrimproved tube of the magnetron type'wherein 'an 'electron gun and magnetic fieldmeans" are provided for pro-- jecting electrons in orbital paths'a-round a central anode; and including a-plurality of setsjo'f cavities past which the electrons travel for ultra high-frequency wave induction the cavities being located at different distances' 'fromthe-anode whereby the maximum'trans'fer of energy is ef-- fected between the moving electronsand the elec" tric'fields of the cavities.

A feature ofthe invention relatesto' a-mag netron tube having means as define fam'airlpr". primary. cavity surrounding'a *centra'l anode; and an electron gun for' projecting ai beam of, elec trons past said" cavity; together with a series of auxiliary cavities surrounding th primarylcav ity butat different" axial distances'from said anode to insure that jafmaximum of ultra high frequency" energy is transferred from the electron beam intothe electric fields 'at the various cavities.

Another featurerelatesto a magiietrontiibef having a central anode surrounded by a 'prim'ary cavity through which'electron'sare projected from an electron gunfor energy transfer" to the" electrical field 'W'ithil'fth 'primarys'cavityi in "con junction with a serie's 10f" secondary "cavities stir rounding. the" primary? cavity and" arranged to cooperate with those electron's whichare not" decelerated by-the p'ri'm'ary cavity "belcwf a" cef tain velocity, so as to successively a from such non-deceleratedlelectrons inthevarijous secondary cavities. As a result; substantially all the electrons 'from the. gunare' utilized converting their motional energy into" induced highfreque'ncj wave energy."

Afurther"featurerelatesto amagne'crcnwube street ener y s Clainis; (ol 3l5ggg having ai -central anode located within a primary cavityfor the abstraction of energy from theelectrons emitted into' said primary cavity, and a" plurality of' secondary cavities-located at 'in-' creased radialdistances from" said anode and electricallyspaced so that the electrons which leave said-primary cavity because of insu flici'ent deceleration;- successively traverse thesecondary cavities'-andare deceleratecl in phase with the electrical= fields-induced in said secondary cavi-' ties A further feature" relates' to a" magnetron tube having a; central anode located within a primary cavity for the abstraction of energy from" the I electrons emitted into-said primary cavity, and a pluralityof l secondary cavities locatedat diffem ent levels'with-respect to the length of the anode sothat the 1 electronswhich arenot sufliciently" decelerated by the l primary cavity, successively pass thesecondary" cavities where they-are decelerated' by transferring their motional energy into: electrical wave energy.- I The above-mentioned and otherfeaturesand' objects of this invention and the'mannerof attaining them will become more apparent and the-invention itself will be best-understood; by

reference to the following'description of anem bodiment of thein'vention taken in conjunction with theaccompanying drawings, wherein:

Fig. 1 is a composite structural and wiring diagram of; an'ultra high-frequency generating system showing the magnetron according to the invention, in plan view.

Pg. 2 is a sectional view ofthe ma'gnetro'nof" Fig. 1, taken-along the line 2-2 thereof.

Fig. 3 is another sectional view of Figi 1, taken alongthe line 3"3 thereof. I

Fig. 4 i a'modiflcation of the arrangement'ofi" Fig; 1.

Fig. 5 is a sectional'view of'the' magnetron'of Fig: 4", taken along the line 5-5"the'recf.'

Thejpresent invention is predicated upon"'the fact that 'when'ele'ctrons from a suitablesouice;

such as an electron gun; are emitted into; or" pasta cavity opening within which'is meatd an anode, a certain percent of the' electio s;

usually 50%; will'findthemselvesin a positive field as they enter or pass the cavity and'thus will be accelerated, resulting in 'a'dimiriiition' of the high frequency energy within th'e cavity.

That is, instead'of'these accelerated elctrcns transferring energyto the electric "fieldf'witlilfl thecavity, they w'ill' withdraw il lfgy therefrom; On the otherh'a'n'dj the remaining'percenttr field and will therefore transfer energy into the cavity field. For convenience of description the accelerated electrons will be referred to herein as wild electrons, and the decelerated electrons will be referred to as tame electrons. Heretofore, no effective attempt has been made to convert the energy of the wild electrons into useful electric field energy, and in fact it has been the usual practice to provide positively charged plates for collecting these wild electrons. Not only does this cause a waste in the conversion of the electron motional energy into electric field energy, but it also causes undesirable conversion into heat energy at the collector plates. These disadvantages are overcome according to the present invention, by allowing or causing the wild electrons to trace orbital paths of greater radii than the tame electrons, and a plurality of auxiliary or secondary cavities are provided at difierent distances from a central anode, for cooperation with the wild electrons so that eventually all the electrons arrive at the secondary cavities in decelerating phase whereupon they are restored to thezone of influenc of the primary cavity and thus reach the said central anode. The positions of these secondary cavities are chosen with respect to the electron orbital radii of the wild electrons so that the electrons which enter the primary cavity or cavities at the incorrect time or phase of the electric field therein, will be caused to continue their orbital motion until they enter or pass the secondary cavities in the correct timing or phasing. Since these wild electrons excite the secondary cavities they are decelerated as a result of their giving up energy to the cavities. This deceleration of the wild electrons results in their returning to orbital paths'of decreasing radii, until eventually they all are brought back into the orbital paths or zones of the tame electrons and finally they spiral into the central anode. Thus, all of the energy given to the initial electrons by the electron gun will be converted into useful radio or ultra highfrequency energy.

Referring to Figs. l3, there is shown a metal body or block I of copper or other good heat conducting metal, having on its interior a primary cavity 2, and a series of secondary cavities 3, 4, 5 and 6. A common anode I is centrally located within the cavity 2. Preferably the body I is formed of two similar half blocks with their opposed faces symmetrically undercut to form the above-noted cavities, and with their outer peripheries hermetically united except for the various lead in openings through which the Various lead-in conductors are hermetically sealed. Preferably the body I is provided with an exhaust opening by which the spaces and cavities within the body can be evacuated, and then the exhaust opening is hermetically closed. If desired, the exhaust opening can be connected to a pump so as to maintain the interior of the body I under continuous evacuation. The central parts of each half block are of smaller transverse thickness than the outer margins of the half blocks so as to form a continuous annular space 8'within the body I which provides a clear path for the electrons as they travel in increasing orbital paths around the anode I. In accordance with Well-known magnetron theory, the cavities 3, 4, 5 and 6, are physically dimensioned so that the oscillations set up in each cavity as the electrons move past it, have a frequency determined primarily by the cavity dimensions. Likewise, the magnetic field which is applied by the magnet poles 9 and I0, is of such a strength and direction as to cause the electrons emitted from the electron gun II to travel around the anode I with an orbital frequency equal to said oscillation frequency. As a result, the oscillations induced in the various cavities reenforce each other and can be taken off from the tube by means of respective small inductive pickup loops i2-I1, whose lead-in ends are hermetically sealed through respective seals I823, which can be connected to a common collector ring through appropriate phase adjusting elements, not shown.

For the purpoe of producing the initial electron velocity, the electron gun is mounted in the annular gap 8 so as to emit electrons past the primary cavity 2. The heating current for the cathode of this gun can be brought in through a pair of lead-ins hermetically sealed through the seal-in 24. Likewise, the various lead-ins for supplying the accelerating and other potentials to the various electrodes of the gun can also be brought in through respective hermetic seals, not shown. Since electron gun structures and their potential supply circuits are well-known in the art, detailed description thereof is not necessary to an understanding of the present invention. A suitable high positive potential is applied between the electron-emitting cathode of the gun and the body I.

While Figs. 1-3 show the auxiliary cavities arranged at greater radial distances from the central anode 7, a similar efiect may be achieved by arranging these auxiliary cavities at levels longitudinally displaced with respect to the length of said anode. Such an arrangement is illustrated in Figs. 4 and 5. The main cavity 25 is defined by cylindrical recesses .26 in a non-magnetic metal block 27, and corresponding cylindrical recesses 28 in the central cylindrical portion 29 of another non-magnetic metal block 30. The central anode 3| is fastened to the member 29 and extends between the opposed central portions of members 21 and 29. Preferably, the member 21 is provided with a dielectric insert 32 into which is fitted the upper end of anode 3|, so as to direct current insulate it from the remaining portion of member 21. Likewise, an

annular body of insulation 33 is sealed between the blocks 21 and 30, so as to direct current insulate these blocks from each other. The block 30 is also provided with an annular space 34, surrounding the central portion 29. The body of block 30 is provided with aseries of four cavities 35, 36, 37, 38, and in each of which is mounted one of the usual inductive pick- up probes 39, 40, 4|, 42-, which pass through respective openings in the block 30 and are hermetically sealed by the respective seals 43, 44, 45, 46. These probes can be connected to a common collector ring, not shown. A suitable electron gun 47 is mounted in a space between the members 21 and 30, so as to emit an electron beam which initially intercepts the right-hand portion of cavity 25. Consequently, the tame electrons passing through cavity 25 spiral back to the central anode 3i. In accordance with one phase of the invention, the block 2! is connected to the negative terminal 48 of a suitable direct current supply source so as toproduce an electric field in the annular chamber 34, which field is directed downwardly towards the bottom of the said chamber. Consequently, the wild electrons which initially leave cavity 25 follow an orbit of greater radius so that they enter the chamber 34 where they are subjected to the above-mentioned electric field causcontinue toexecute an-orbital path around the center of the device. In other-words, they ,execute a substantially helical .orbit, and in doing so they successively pass the auxiliary cavities to 38, where their electron energy is transformed into electric field energy in these respective cavities in the same manner as was described above *in connection with the embodiment of Figs. l-to 3. -It-will be understood of course, that the-device is 'providedwiththe appropriate magnetic field extending from the magnetic pole 49 to the magnetic pole 50, between which the device is mounted. In order to accentuate the helical orbits of the wild electrons, the electron gun 25, instead of being mounted in a plane perpendicular to the length of the anode 3|, can be tilted downwardly with respect to the auxiliary cavities. It will be understood of course, that all the cavities are connected together to a common collector ring through properly proportioned electric lines as is well-known in the magnetron art, so that the energies in all the cavities reenforce each other. While the drawing shows a device having a single main cavity and a series of auxiliary cavities located in a common lower plane, it will be understood that two' or more sets of such auxiliary cavities can be provided similar to the cavities 35 to 38, and located at respectively lower planes than cavities 35 to 38 so as to provide additional assurance that all the wild electrons are eventually converted into tame electrons.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention.

What is claimed is:

1. An electron discharge device of the ma netron type comprising an electron source and an anode, a magnetic field source mounted adjacent said anode to provide a magnetic field transverse to the initial path of electrons from said source to cause said electrons to follow spiral trajectories from said electron source about said anode, a plurality of main cavity resonators mounted in a circle about said anode in energy transfer relation with electrons following said trajectories whereby certain of said electrons are accelerated to follow a wider spiral trajectory and a plurality of auxiliary cavity resonators mounted at a greater distance from said anode than said main resonators in energytransfer relation with said initially accelerated electrons following said wider trajectory whereby said auxiliary resonators decelerate saidelectrons by energy transfer sufficient to cause them to return to energy transfer relation with said main resonators.

2. An electron discharge device according to claim 1 in which said auxiliary cavity resonators are located at a difierent distance from said electron source as compared with the distance of said main resonators from said source.

3. An electron discharge device according to claim 1 in which all said resonators are interconnected for the addition of electric energy transferred thereto by said electrons.

4. An electron discharge device of the ma netron type comprising an electron source and an anode, a magnetic field source mounted to provide a magnetic field transverse to the initial path of electrons from said source to cause sa d electrons to follow spiral trajectories from said source about said anode, a main cavity res- 4 onator mounted. aboutwsaid: anodes; imrenetf y W transfer :relation with: .-the.-. .electron'crfollow-ing -=said-spiral trajectory whereby .-certain-;; of ;:;said electrons are'accelerated. to follow. a; wider: tra- -jectory,- and an auxiliary-resonaton-mountediat a greater distance fromsa'id' electron source than said main resonator, and from. said anode ethan the outer periphery 'of said-main resonator-aim energy-transfer relation I withsaid accelerated electrons following said wider: trajectory: whereby said auxiliary resonator deceleratesthegelectrons by energy transfer sufficient to cause them to return to energy transfer relation past said main resonator.

5. An electron discharge device of the magnetron type, comprising a central anode, means defining a main cavity resonator mounted adjacent said anode, an electron gun mounted adjacent said main resonator for developing an electron beam which in its initial trajectory is intercepted by said main resonator to transfer energy from the moving electrons to the electric field within said main resonator, and means for causing the electrons of said initial trajectory which are not sufiiciently decelerated by said main resonator to follow substantially spiral paths back to said anode, the last-mentioned means including a magnetic field source mounted transverse to said spiral paths and a plurality of auxiliary cavity resonators located at greater radial distances from said anode than said main resonators.

6. Ultra high frequency generating apparatus comprising a conductive metal block provided with a central space forming a main cavity resonator and a plurality of spaces about said central space forming auxiliary cavity resonators and an annular space communicating with said resonator at its inner margin and with said auxiliary resonators at its outer margin, an anode mounted in the center of said main resonator, an electron gun mounted adjacent said main resonator to project electrons therethrough, and a magnetic field source mounted transversely to the path of said electrons.

7. Ultra high frequency generating apparatus comprising a metal block provided with an annular space therein, a plurality of auxiliary cavity resonators located about said annular space and communicating therewith, a metal plate defining with said block a central main cavity resonator, an electron gun mounted adjacent said main resonator for projecting electrons therethrough, means insulatingly spacing said metal plate from said block, a source of direct potential applied across said plate and block to sub- J'ect the wild electrons from said main resonator to a displacing electric field to cause them to travel in a helical trajectory past said plurality of auxiliary resonators, means connecting all said resonators together so that energy transferred to electromagnetic fields therein by the electrons from said gun are in additive relation, and a magnetic field source transverse to the path of electrons from said gun to cause said electrons to trace helical trajectories from said gun to said anode.

8. In a magnetron oscillator having an electron gun to direct a stream of electrons along a first path, a magnetic field source mounted transversely to the said first path of electrons from said gun to cause said electrons to move in a circular path, a main cavity resonator mounted adjacent said circular path to cause certain of said electrons to be decelerated and others to 7 be accelerated, a collector electrode mounted REFERENCES CITED at the center of said circular path, the improve- The following references are of record in the ment comprising an additional cavity resonator file of this patent: mounted adjacent said circular path and further from said collector electrode than said main cav- 5 UNITED STATES PATENTS ity resonator to extract energy from said ac- Number Name Date celerated electrons and cause them to move back 2,232,050 Clavier et a1 Feb. 18, 1941 1 into energy transfer relation with said main res- 2,289,220 Smith July 7, 1942 onator and a coupling between all said resona- 2,409,038 Hansell Oct. 8, 1946 tors for combining high frequency energies de- 10 2,473,399 Spencer June 14, 1949 veloped therein. 2,496,500 Spencer Feb, 7, 1950 ROBERT S. BAILEY.

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