US2160798A

US2160798A - Electron discharge apparatus

Info

Publication number: US2160798A
Application number: US111810A
Authority: US
Inventors: Gordon K Teal
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1936-11-20
Filing date: 1936-11-20
Publication date: 1939-05-30
Anticipated expiration: 1956-05-30
Also published as: GB521077A; GB500447A; FR49655E; FR824648A; FR49980E; DE886343C; GB500448A; US2236041A; US2245605A; CH214485A; NL49799C; GB500170A; US2160797A; US2160796A; CH208067A; GB505663A; US2134718A; US2160799A; BE431298A; GB502528A

Description

May 30, 1939. 3 K, TEA| 2,160,798

ELECTRON DISCHARGE APPARATUS Filed Nov. 20, 1936 3 Sheets-Sheet l g VARIABLE LIGI-l7 sowzce DIRECT/ON MAGNE TIC FIE [.0

G. K. TEAL May 30, 1939.

ELECTRON DISCHARGE APPARATUS Filed Nov. 20, 1936 3 Sheets-Sheet 2 FIG. 4

ATTORNEY May 30, 1939. G. K. TEAL ELECTRON DISCHARGE APPARATUS Filed Nov. 20, 1936 3 Sheets-Sheet 3 FIG. 7

VARIABLE -L/GHT SOURCE R/.. m MT V |v N 6 N /G m n y mm 5 m W m MA GNET/L FIELD I 4 DIRECTION OF ATTOPNEY lntented May 30, 1939 UNITED STATES PATENT OFFICE 2,160,798 ELECTRN nr scHancn APPARATUS Application Novem her 20, 1936, Serial No. 111,810

15 Claims.

This invention relates to electron discharge apparatus and more particularly to such apparatus adapted to amplify high frequency impuises and including electron discharge .devices having.

5 secondary electron emitting electrodes.

one object of this invention is to facilitate the attainment of faithful translation of high frequency s'ignals.

Another object of this invention is to simplify m electron discharge amplifying apparatus whereby the number of component elements necessary to produce a high degree of amplification is reduced. Another object of this invention is to obtain a high signal to noise ratio in electronic amplifiers.

5 Still another object of this invention is to inr crease the efliciency of electron discharge devices including secondary electron emitting electrodes.

A 'iurther object of this invention is to expedite the construction of electron discharge devices havihg secondary electron emitting electrodes and;to facilitate the sensitizaton of such electrodes theren.

Inone illustrative embodiment of this invention, electron discharge apparatus comprises a primary cathode, a collector electrode or anode spaced 'from the primary cathode, and a plurality 01. auxiliary electrodes or secondary cathodes disposed in superposed relation between the primary cathode and the collector electrode or anode.

30 These auxiliary electrodes or secondary cathodes may be, for example, annular members of cylindrioal or frusto-concal form, arranged coaxially with one another and with the primary cathode and the collector electrode or anode. Portions of 35 the secondary cathodes, for example, the inner surfaces thereof, may be coated or treated to assure copious emission of secondary electrons therfrom.

During operation of the device, a strong mag- 40 netic fleld is produced, as by a coil encompassing th lection discharge device, axially cithe electrodes or the device and adjacent the coated or treated portions of the secondary cathodes, and th"secondary cathodes are maintained at suc- 45 c'ssivel increasng positive potentials with re- Spect to the primary cathode. The primary cathode may be energized in any suitable manner to cause rmissiontberefrom, and the electrons thus exhifited, under the influence of the potentials and the magnetic field extant in the device, are

' directed to and impinge. upon the secondary cathodeh.rest the primary cathode. As a result, secondary electrons are released from this cathodepahd these electrons are directed to and im- 55y pinge -unonthe next adjacent secondary cathode.

This phenomenon is repeated at each of the secondary cathodes down to the one furthest removed from the primary cathode. The secondary electrons emanating from this last secondary cathode are drawn to the collector electrode or anode and constitute the output current of the device.

Inasmuch as portions of the secondary cathodes are treated or coated, each primary or-secondary electron impinging thereon will cause the release of a plurality of secondary electrons so that in effect an electron multiplication, and hence an amplification, occurs at each of the secondary cathodes. The magnitude of the secondary electron streams may be varied by varying the emission from the primary cathode or by modulating the primary electron stream flowing from the primarycathode to the secondary cathode thereadjacent.

In order to increase the electron flow between the various electrodes, an auxiliary or accelerating electrode may be provided. This electrode may be, for example, a linear wire disposed in the axis of alignment of the secondary cathodes.

It may be maintained at a positive potential somewhat higher than that of the first secondary cathode so that it assures a velocity component of the electrons away from the coated or treated portions of the secondary cathodes.

In another embodiment, a plurality of coaxial auxiliary or accelerating electrodes may be employed, one for each of the secondary cathodes and Iaterally alignedtherewith. Each of these accelerating electrodes may be maintained at a positive potential somewhat higher than that upon the corresponding secondary cathode.

The invention and the various features thereof will be understood more clearly and fully from the following detailed description with reference to the accompanying drawings in which: V

Fig. 1 is an elevational view of electron discharge apparatus illustrative of one embodiment of this invention, a portion of the external coil and of the enclosing vessel and a portion of the anode of the electron discharge device being broken away to show the electrodes more clearly;

Fig. 2 is a view in cross-section of the electron discharge device illustrated in Fig. 1, showing the configuration of the primary and secondary cathodes and the mounting therecf;

Fig. 3 is an eIevational view in perspective of another illustrative electron discharge device constructed in accordance with this invention, a portion of the external coil, of the enclosng vessel and of one of the electrode supports being broken away to show the electrode structure more clearly;

Fig. 4 is an elevational view partly in crosssection of the electr0de structure of the device shown in Fig. 3;

Fig. 5 is a circuit diagram et an amplifier constructed in accordance with this invention and including an electron discharge device of the de sign shown in Fig. 1 or in Fig. 3;

Fig. 6 is an elevational view in perspective of an electron discharge device illustrative of another embodiment of this invention, a portion of the external coil and portions of the enclosing vessel being broken away to show the internal structure more clearly;

Fig. 7 is a view in elevation and partly in crosssection of the electrode assembly emboflied in the discharge device shown in Fig. 6; and

Fig. 8 is a circuit diagram of an amplifier including an electron discharge device of the construction illustrated in Fig. 6.

Referring now to the drawings, the electron discharge device shown in Figs. 1 and 2 comprises an elongated cylindrical enclosing vessel m having a stem il at one end, the stem being provided With a press i2 and a pair of parallel insulating arms or uprights l3. Disposed between the uprights l3 is a primary cathode Id, a collector electrode or anode i5 and a plurality oi auxiliary or secondary cathodes 36 to E6 inclusive, the several electrodes being coaxially arranged and L equally spaced and preferably being of the same diameten The primary cathode I 3 and the secondary cathodes [6 may be bands of metal having portions, preferably the inner surfaces thereof, coted or treated to assure copious electron emission therefrom. For example, the several cathodes may be of silver having their inner surfaces oxidized and treated with caesium to form a laver or coating of silver, caesium oxide and some free caesium.

The primary and secondary cathodes are sup ported by metallic rods or wires il embedded at one enclin the insulating uprights I3 and suitably afiixed at the other to the metallic banda Suitable potentials may be impressed upon the cathodes M and l6 through leading-in conductors i8 which are connected to the rods or wires il and are sealed in and extend through the cylindrical Wall of the enclosing vessel J. The external portions of the conductors ne preferably are encased in insulating maQterial such as rubber sleeves i9.

The anode or collector electrode 95, which may be substantially conical in form and apertured at its apex, is supported by a pair of metallic rods or wires 20 embedded in the press i2, one of the rods or wires 20 having a leadingin conductor 29 connected thereto.

Disposed within the cathodes and the anode or collector electrode, and preferably in the axis thereof, is an auxiliary or accelerating electrode which may be a linear rod or wire 22, supported at one end by a rigid stub or wire 23 and at the other end by a resilient wire 26 embedded in one of the arms or uprights i3. A suitable potential may be applied to the accelerating electrode 22 through a leadingin conductor 25.

The enclosing vessel au may be encompassed by a coil 26 or a cylindrical magnet adapted to produce an intense concentrated magnetic field of constant strength parallel to the longitudinal axis of the vessel il), toward the collector electrode, and adjacent the inner surfaces of the cathodes M and 66.

Preferably the coil or magnet issu constructed that the magnetic field is of greatest intensity in the vicinity of the primary cathode and decreases uniformly toward the collector electrode in order to compensate for the non-uniformity of the electrostatic field between the cathodes and the auxiliary or accelerating electrode, said electrostatic field bains strongest in the vicinity of the primary cathode and decreasing substantially uniformly to adjacent the secondary cathode nearest the collector electrode.

During operation of the device, the secondary cathodes i5 are operated at successively and uniiormly increasing positive potentials with respect to the primary cathode m. That is to say, during operation the secondary cathode 16 may have a positive potential of the order of 250 volts With respect to the primary cathode M applied thereto and each of the secondary cathodes IE to m may have a positive potential of the order of 250 volts higher than that upon the next preceding cathode applied thereto. The anode or collector electrode l5 may be at a potential of the order of 500 volts positive with respect to the last of the secondary cathodes l6 and the auxiliary or accelexating electrode 22 may be at a potential of the order of 1750 volts positive with respect to the primary cathode M.

The potentials for the electrodes may be obtained conveniently as shown in Fig. 5.

The cathodes 3 and l6 are connected to equally 4 spaced tape on a potentiometer 21 which is encrgized from a suitable source such as a rectifier 28. Because of the large current drain, a separate source, such as a battery 29 is provided for suppiying a suitable positive potential to the anode or collector electrode I5. An output or utilizatien circuit may be connected to the anode or collector electrode and the source 29. A suitable source 3l! of variable light is provided for encrgizing the primary cathode M. The auxiliary electrode 22 may be connected to a tap on the battery 29.

When the primary cathode M is energized, electrons are emitted therefrom and these electrons under the influence of the magnetic field produced by the coil 26 and of the potentials upon the first secondary cathode I5 and upon the auxiliary electrode 22 are directed toward and impinge upon the inner surface of the secondary cathode N and cause the emanation cf secondary electrons therefrom. Inasmuch as the inner surface of this secondary cathode is coated or treated as described heretofore, the secondary electron current therefrom will be materiafly greater, for exemple 8 times the primary electron current thereto. Consequently, in efiect, an electron multiplication and an amplification of the signal corresponding to the primary current from the cathode i results. The secondary electrons emanating from the cathode l6 are influenced by the magnetic field of the coil 26 and the potentials upon the cathode 16 and the auxiliary electrode 22 and impinge upon the secondary cathode W to cause the emanation of other secondary electrons therefrom. The phenomenon is repeated at each of the secondary cathodes down to the last one IE so that six electrone multiplications and amplifications results. The secondary electrons from the secondary cathode flow to the collector electrode or anode (5 and constitute the output current of the device.

As the energization of the primary cathode M is varied in accordance With a signal, the output current to the anode or collector electrode with integral parallel flanges 38 to which a clip 39 is secured, as by a bolt 40. Each of the clips 39 is bent around and securely grasps one of a plurality o f tubular arms or upfights 4l extending from the stem 42 and thereby supports the cathode with which it is associated. Leadingin conductors 43 extend through the tubular uprights 41 and are aflxed, as by welding, to the flanges 38.

The cathodes 36 and 31 may have portions, pref erably the inner surfaces thereof, coated or treated, as deScribed heretofore in connection with the description of the apparatus shown in Fig. 1, to provide copious electron omission.

The anode or collector electrode 44 also may be funnel-shaped or frusto-conical and is provided with an integral fiange 45 affixed to a rigid support wire 46 embedded in the press 41 on the stem 42 and having a leading-in conductor 48 connected thereto. The anode or collector electrode 44 preferably is coaxial with the primary nected to Opposite ends thereof.

and secondary cathodes and tapers at the same rate as the cathodes.

Disposed between the lowermost secondary cathode 51 and the collector electrode 44 is a shieid or screen electrode 49 comprising a plurality of parallel wires supported from the press 41 by a pair of rigid uprights 5l), one of which has a leading-in conductor 5l connected thereto. This electrode serves to prevent reaction upon the cathode 31 of potential variations upon the anode or collector electrode. It may be operated at a potential of 135 volts positive above the cathode 31 The auxiliary or acceierating electrode 22 may be a linear metallic rod or wire disposed in the axis of the cathodes and anode, and is supported at one end by a helical spring 52 carried by a band 53 clamped about one of the arms or uprights M, and at the other end by a rigid wire 54 embedded in the press 41. Suitable electrical connection to the electrode 22 may be made through leading-in

conductors

55 and 56/con- If desired, a current may be passed through the conductor 22 to produce a magnetic field.

In order to produce a reatively intense magnetic fieid the conductor 22 may be of large diameter and hence of high current carrying capacity, or alternatively, a plurality of parallel conductors may be employed.

The enclosing vessel may be encompassed by a fieid coi], such as the coi] 26, and the device may be connected in circuit as shown in Fig. 5. The operation of the device is the same as set forth fully heretofore in connection with the description of the apparatus shown in Fig. 1. It may be noted that the electrode construction in the device shown in Figs. 3 and 4 provides a greater concentration of electrons within the various cathodes and assures flow of substantially all the electrons emanating from each of the cathodes toward the next adjacent electrode whereby a high operating efliciency is obtained.

' or treated to assure copious emissi In the embodiment of the invention illustiated in Figs. 6, 7 and 8, the electron dischargfle device comprises an enclosing vessel, l li.h.ing'a stem 51 provided intermediate itsihtisfWithanintegral annular fiange 58 and:h.ving clarped a thereabout metallic bands or colars 59 from Wlh a unitary electrode assembly is supported. ,Ihe bands or collars 59 have aiflxed threto}ja;i lurality, for example three, of rigid.metllic,s&iixports 60 which are securely fastened 'to the arms SI of a tri-armed supporting spider.) The" arms. 61 are channel-shaped and tightly.flttd threin and held thereby are insulating urights 62,.10r example strips of mica or the likta.fl]1hf insulating uprights 62 are maintained spaced relation at the end thereof remote'frdni the,- stem 51 by a spider 63 having.channelshapd 62 is provided witha pluralit .1 ,fli rs 4 g for supporting a primary cathode 65 Za.nd aflplurality of secondary or auxiliary cathode 66 to 66 inclusive. As shown clearly he cathodes 65 and 56 are fruste-cohlc axlal and have their adjacent baj' Preferably the several cathodes are; 0; dimensions and have their inner surf trous therefrom. Each cathode bears sloping edge of one of the finger uprights 62 and has one of its bas lateral edge of another of the fi cathodes may be iocked to the firig tegral flanges or projections 61 cl against.

Disposed adjacent the lowerm ost cathode 66 is a collector electrod which may be a metallic annulus liajvi 11 clips 69 thereon frictionally fitted in slot in uprights 62. Preferably the collecto or anode 58 is mounted coaxially with

odes

65 and 66 and at right angles of alignment of the electrodes.

electrode and having aflixed thereto spaced clips 1! which are securely fitted in slots in thjinS- lating uprights 62.

Electrical connection to the various electrodes may be' established through wires 12 each con;-- nected to one of the electrodes and to one of"a plurality of leadi ngin conductors 13 sealed in the annular fiange 58 and projecting thereirom The wires 12 may be encased in insulating n terial such as glass sleeves l4.

Extending betWeen the spiders 6l and"iif triangular hollow insulating pillar or supxof l which may be composed, for example, f of mica or the like fitted at their ends in ch nels in the spiders. The pillar or sufipp carries a plurality of frusto-conical elegti{ 16 to 16 inclusive, one for each of the c fcl 65 and 65, which are coaxial with one and with the cathodes 65 and 86 and electrodes 16 encircle the support 15 and a1 vided with flanges 11 frictionally fitted in in the strips of which the support is camp Preferably the electrodes 16 are 01 the same dimensions. Electrical connection to the electrodes,

to one of the leading-in conductcrs l3. The and the electrodes i6 may have their outer surportions of the conductors l3 Within the support 75 may be insulated from one another by encasing insulated membeis such as glass sleeves 79.

The enclosing vessel m of the device shown in Figs. 6 and 7 may be encircled by a field coil such as the coi] '26.

During operation of the device, the secondary cathodes 66, screen electrode in, and anode or collector electrode 68 are maintained at successively increasing positive potentiels With respect to the primary cathode 65. The auxiliary electrodes 16 also are operated at successivcly increasing positive potentials, each of these electrodes being at a positive potential somewhat above that upon the corresponding one of the cathodes and 66. For example, the auxiliary electrode 16 may be at a potential of the order et 135 volts positive with respect to the primary cathode, and the electrode i6 may be at a posi-' tive potential of the order of 135 volts above that upon the electrode 16 and hence of the order of 135 volts positive with respect to first secondary cathode 66. The other auxiliary electrodes 16 to 15 may be at potentiels equally more positive with respect to the secondary cathodes 66 to 66 respectively.

The operation of the device shown in Figs. 6

and 7 is substantially the same as that of the device shown in Fig. 1 and described in detail heretofore. The electrons emanating from each of the

cathodes

55 and 66 come under the influence of at least three forces, namely, that of the magnetic field, of the potentials upon the cathodes and the collector electrode and of the potentiels upon the auxfliary electrodes, the resultant of the forces being such that the electrons traverse spiral or arcuate orbits in passing from one of the cathodes toward the next adjacent electrode.

The various electrodes may be connected in circuit as shown in Fig. 8. The

cathodes

65 and 56 and the screen electrode Il! may be connected to equaily spaced tans on a potentiometer 21 supplied by a suitable source such as a rectifier 28. The anode or collector electrode 68 may have a suitable potential .applied thereto from a separate source such as a battery 29. Each of the auxiliary electrodes 16 to 16 is connected,

as shown, to the next succeeding secondary cathode and the auxiliary electrode 16 is connected to the screen electrode I0. The primary cathode 65 may be energized by a light beam emanating from a suitable light source 30.

In the amplifier circuit shown in Fig. 8, the

electrodes

65 and 66 are operated as cathodes and the electrodes 16 serve primarily to provide a field substantially normal to the emitting surfaces of the

cathodes

65 and 66. These electrodes may be operated also in the reverse relation; that is to say, the outer surfaces of the electrodes 16 may be coated or treated to allow copions electron emisson therefrom and the

electrodes

65 and 66 may be left uncoated. The electrodes 16 may then be operated as cathodes, the electrode 16 serving as the primary cathode and theelectrofles 16 to 16 serving as secondary cathodes, and the

electrodes

65 and 66 may be operated at positive potentiels, each at a patential somewhat above that of the electrode 16 laterally opposite.

In another arrangement, both the

electrodes

65 and 56 and the electrodes 16 may be operated as cathodes. That is, the

electrodes

65 and 68 may have their inner surfaces treated or coated faces similarly coated or treated. The potentials upon the electrodes then may be so related that electrons emanating from the outer electrodes impinge upon the inner electrodes t0 cause the release of secondary electrons therefrom and vice versa. For exampie, the electrode.65 may be utilized as the primary cathode and the eletrons emitted therefrom directed to and imbinge upon the cathode 76 to cause the release of secondary electrons therefrom. These secondary electrohs are directed to and impinge upon the electrode 66 to cause the release of other secondary electrons therefrom. This action is repeated along the electrode structure, au electron multiplication and hence amplification obtaining 'at each tion have been shown and described, it will be understood, of course, that they are merely illustrative of the invention and that various modifications may be made therein. For example, although devices having four and flve secondary cathodes have been illustrated, a greater or lesser number may be utilized depending upon the degree of amplification desired. Aiso, although the primary cathodes have been disclosed as of the photoelectric type, other types such, for example, as thermionic, directly or indirectly heated may be used, and a separate control electrode or grid may be employed to vary the intensity of the electron stream from the primary cathode to the next adjacent secondary cathode. Moreover, the auxiliary electrode 22 may be of magnetio material and permanently magnetized to produce a field thereadjacent and directed toward the collector electrode. Furthermore, the primary cathodes may be coated or treated on their exterior surfaces instead of their interior surfaces and the anode or collector electrode cathodes disposed in aliment and afiixed to said trame, conductors connecting said electrodes to said leadingin conductors, and insulating means encasing said connecting conductors.

2. Electron discharge apparatus comprising a primary cathode, a collector electrode, and a plurality o! superposed fmstooonical auxiliary electrodes between said cathode and said collector electrode and havingportions thereof adapted to emit secondary electrons, said auxiliary electrodes being coaxial and partially nested.

3. Electron discharge apparatus comprising an enclosing vessel having a stem, a plurality of insulating uprights extending above said stem and longitudinally of said vessel, a primary cathode, a collector electrode, a plurality o! coaxial annular secondary cathodes mounted between said uprights and disposed between said primary cathode and said collector electrode, a coating of electron emissive material on the inner surface of said secondary cathodes, and supporting members projecting outwardly irom said secondary cathodes and aflixed to said uprights.

4. Electron discharge apparatus comprising a stem, a primary cathode. a collector electrode, a plurality ci. annular secondary cathodes between said primary cathode and said collector electrode, a plurality of insulating uprights extending Irom said stem, means supporting each of said secondary cathodes from a corresponding one of said uprights, and individual leading-in conductors for said secondary cathodes extending through said uprights.

5. Electron discharse apparatus comprising a primary cathode, a collector electrode, a plurality cf separate annuiar secondary cathodes mounted in and to end relation between said primary cathode and said collector electrode, and electrode means within said secondary cathodes, said electrode means and said secondary cathodes having the opposed surfaces thereof at an oblique angle to one another whereby said means when energized produces an electrostatic fleld at an oblique angle to said secondary cathodes, adjacent ends ci successive secondary cathodes being in immediate proximity. 7

6. Electron discharge apparatus comprising a primary cathode, a collector electrode, a plurlity 01 superposed annular secondary cathodes between said primary cathode and said collector electrode, said secondary cathodes being coaxial with one another and in alignment with said primary cathode,individuai leading-in conductors for said secondary cathodes. and a plurality ofcausing electrons' emanating'irom said cathodes to flow toward and impinge upon the next succeeding cathode toward said collector electrode, each secondary cathode extending at least to the boundary of the nearest end of the preceding cathode. r

7. Electron discharge apparatus comprising a primary cathode. a collector electrode, a plurality of sflmrposed annular secondary cathodes between said primary'cathode and said collector electrode, and a plurality oi superposed auxiliary electrodes lateraily opposite said secondary cathodes. v

8. Electron discharge apparatus comprising a primary cathode. a collector electrode, a plurality o! superposed, coaxial annular secondary cathodes between said primary cathode and said collector electrode, and a piuraiity o! superbosed annular auxillary electrodes coaxial with said secondary cathodes and lateraily opposite said secondary cathodes.

9. Electron discharge apparatus comprising a primary cathode, a collector electrode, a plurality of superposed coaxial frusto-conicai secondary cathodes between said primary cathode and said collector electrode, and a plurality cf superposed coaxial annular auxiliary electrodes each lateraily opposite one of said secondary cathodes.

' 10. Electron discharge apparatus comprising a primary cathode, a collector electrode, and a plurality 01 rows of auxiliary electrodes between said cathode and said collector electrode, one of said rows being disposedwlthin another, and the auxiliary electrodes in one of said rows being adapted to -emit secondary electrons.

11. Electron discharge apparatus comprising a primary cathode, a collector electrode, and a pair of coaxial rows 01 coaxial annular auxiliary electrodes between said cathode and-said collector electrode, one of said rows being within the other, and the auxiliary electrodes in one of said rows having electronemitting surfaces directed toward the electrodes in the other of said rows.

12. Electron discharge apparatus comprislng a primary cathode, a collector electrode, and a pair of coaxial rows cf coaxial frusto-conical auxiliary electrodes between said cathode and said collector electrode, said rows of electrodes being disposed one within the other,and the electrodes in one said rows having electron emitting surfaces facing the electrodes in the other of said rows.

13. Electron discharge apparatus in accordance with the next preceding clainri wherein the electrodes in said rows taper in opposite directions.

14. An electron multiplier comprising a primary cathode, a collector electrode, a plurality cf secondary cathodes between said primary cathode and said collector electrode, a plurality of auxiliary electrodes for producing an electrostatic field adjacent said primary and secondary cath- Odes, and means for producing a magnetic field adjacent said primary and secondary cathodes and decreasing in lntensity towatd said collector electrode,

15. An electron multiplier comprising an aunular primary cathode, a plurality of separate annular secondary cathodes in end-to-end relation, haVing adjacent ends thereof in immediate