US2193579A - Electron discharge apparatus - Google Patents

Description

' March 12, 1940. E, BR CE 2,193,579

ELECTRON DISCHARGE APPARATUS Filed Jan. 26, 1938 I 3 Sheets-Sheet 1 m um mm Ill i n 'upm' 4L Y i; *5

ANODE CURRENT IN MILL/AMPEPES -|2--|o -s -a -4 -2 o CONTROL VOLTAGE WHEN ANODE I25 u ACCEL 4.0 K CONTROL =-5.5 l!

ANODE CURRENT IN MILL/AMPERES 5 CONTROL 0 A ELE TR 0 2o 40 so so I00 I20 I40 I60 47 ANOOE VOLTAGE INVENTOR ANODE E. BRUCE ACCELERAT/NG ELECTRODE c4 THODE Walla?! 6 AT TORNEV ACCELERA TING ELECTRODE s Sheets-Sheet 2 FIG. I? I CAT/{ODE FIG. /4

E. BRUCE 8 0 K JO I20 INVENTOR E. BRUCE ATTORNEY ANODE VOLTAGE 04am a. 14-24% OUTPUT wwkmniifii 3 K553. meek m w a 6 4 2 o ELECTRON DISCHARGE APPARATUS Filed Jan. 26, 1938- FIG. /3

March 12, 1940.

FIG. 4

INPUT CONTROL VOLTAGE March 12, 1940. E. BRUCE 2,193,579

ELECTRON DISCHARGE APPARATUS Filed Jan. 26, 1938 S Sheets-Sheet 5 ANODE CURRENT IN MILLIAMPERES Avon: +230 u ACCEL. [6 u 5 1 I I l 4 -|zo no.0 a.o -s.o .o -z.o o

colvmb'L VOLTAGE waemajuwa A 7' TORNEV Patented Mar. 12, 1940 ELECTRON DISCHARGE APPARATUS Edmond Bruce, Red Bank, N. 'J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a'corporation of- New York Application January 26, 1938, Serial No. 186,950

zoo-aims. (01. 250-27) This invention relates to electron discharge apparatus and more particularly to such apparatus A as disclosed in my application Serial No. 134,008, Vfiled March 31, 1937, of whichthis application is in part a continuation, including an electron discharge device of the electron beam type.

In the specific form of electron discharge apparatus disclosed in my prior application above identified, the electron discharge device comprises 16 a cathode, a pair of spaced grid electrodes surrounding the cathode, and an anode outside of theoutergrid electrode. Each of the grid electrodes comprises a plurality of spaced linear ele-. v ments, parallel to each other and to the cathode, m the corresponding elements of the two grid electrodes being in radial alignment with one another and with the cathode. The output electrode or anode includes a plurality of linear elements mounted parallel to the cathode, each of these 20 anode elements being in alignment with thecathode along agradius bisecting the space between successive corresponding elements ofthe grid electrodes. 1 In such apparatus, it was found that forspecie fie d conditionsof operation, the control grid potentiakanode. current characteristic included a region wherein a negative transconductance ob tained, thatis, a region wherein'the anode cur-' also as the ratio of the amplification factor to If the transconductance is the anode resistance. to be negative, oneof two possibilities must obtain, namelveither a positive amplification factor vw anda negative anode resistance or a negative amplification factor and a positive anode resistance. One general object of this invention is to obtain a negative transconductance in electron discharge d'evicesp I 15 More specifically, objects of this invention are: To increase the magnitude of the negative transconductance in electron discharge devices having a linear anode or output electrode and a multiele- 1 went control electrode or grid; I

a negative anode resistance in electron discharge devices, without secondary emission from the anode; i To increase the range of grid or control elecelement.

To obtain a positive-amplification factor and trode potentials wherein a negative transconduct ance is'exhibited; and I Toobtain a plurality of spaced regions in the operating characteristic of electron discharge devices wherein the anode oroutput current de-, 5 creases as the control-electrode or grid potential becomes less negative. 1

In one illustrative embodiment of this invention, electron discharge apparatus comprises an electron discharge device having a cathode, a 10 plurality of linear anode elements disposed about the'cathode and parallel thereto .and to one another, and a control electrode or grid. The control electrode or grid comprises a plurality of linear rods or wires so mounted that each anode 15 element has thereabout a plurality of these rods or wires located in an arcuate boundaryat least partially encompassing the corresponding anode The constant potentials upon the various electrodes are such that, throughout a defi- 3 nite rangeofgrid or control,electrode potentials,

" the output or anode current'decreases asthe grid The invention and the features thereof will be understood clearly and fully' from the following detailed description with reference to the accompanyingdrawings in which: I

Fig. .l is a perspective viewof an electron discharge device illustrative of one embodiment of 3Q this invention, a portionottheenclosing vessel and of theelectrode structure being broken away to show the inner electrodes more clearly; v

. Fig. Zis a view in section, and partly diagrammatic, of the electrodes in the device s'hown in Fig. 1, illustrating the arrangement and-electrical association of the various. electrode elements;

Fig. Sis a diagrammaticfragmentary view of aportiono'f the electrodes in the device illustrated in Figs. 1 and 2, showing clearly the relative po- 40 sitions of the anode and control electrode or grid j elements; I r v Fig; 4 is a circuit diagramz illustrating a typical circuitalassociation of the electrodes of theelec-f tron discharge device shown in Fig. 1;

5 and 6 are g'raphsshowing .the relaticnship between the control electrode or grid potene tial and the output or anode currenhand between A the anode voltage and anode current respectively,

of'an electron discharge device of the construc,- -5o 1 tion illustrated in Fig. 1, connected incircuit as illustratedin Fig. 4;

Fig. 7 is a perspective view of an electron disv charge device illustrativeof another embodiment r of this. invention; Y I v Fig. 8 is a view partly diagrammatic and partly sectional illustrating the arrangement and electrical association of the electrode elements in the embodiment of this invention illustrated in Fig. 7;

Fig. 9 is a diagrammatic fragmentary view showing clearly the space relation of the anode and control grid elements in the embodiment of this invention illustrated in Fig. 7;

Fig. 10 is a graph illustrating a typical control electrode potential-anode current characteristic of an electron discharge device of the construction illustrated in Fig. '7;

Fig. 11 is a view partly diagrammatic and partly sectional of the electrodes in an electron discharge device illustrative of still another embodiment of this invention;

Fig. 12 is a diagrammatic fragmentary view showing clearly the relation of the electrode elements in the electron discharge device illustrated in Fig. 11; and

Figs. 13 and 14 are graphs showing typical control electrode potential-anode current and anode voltage-anode current characteristics respectively, of an electron discharge device of the construction illustrated in Fig. 11.

Referring now to the drawings, the electron discharge device shown in Fig. 1 comprises an evacuated enclosing vessel 20 having a stem 2| at one end and having suitably aflixed thereto a base 22 carrying terminal prongs 23 through which the electrodes of the device may be associated with external circuits.

Embedded in the press 24 of the stem 2| and arising therefrom are parallel, rigid, metallic supports or uprights 25, one of which is connected electrically to one of the terminal prongs 23 by a leading-in conductor 26. An insulating disc 21, for example, of mica, is affixed tothe supports or uprights 25 adjacent the upper end thereof, as by clips 28 which may be welded to the uprights or supports. Similar spaced insulating discs 29 and 30, which also may be of mica or the like, are affixed to the supports or uprights 25 by suitable clips 3|, which also may be welded to the uprights or supports.

An elongated linear cathode, which may be either a filament or of the equipotential heater type, is supported between the insulating discs 21, 29 and 30. In the form shown in Figs. 1 and 2, the cathode comprises a cylindrical metallic sleeve 32, coated on its outer surface with a thermionic material, one end of which extends through and is fitted in central apertures in the lower insulating discs 29 and 30 and the other end of which is reduced, as indicated at 33, and fitted in a central aperture in the upper insulating disc 21. The cathode sleeve 32 encloses a heater filament 34 embedded in or threaded through a suitable ceramic or insulating body 35. Heating current may be supplied to the filament 34 through leading-in conductors 36 embedded in the press 24 and connected. to corresponding ones of the terminal prongs 23. Electrical connection to the cathode 32 may be established through a leading-in conductor 31 also embedded in the press 24 and connected to one of the terminal prongs 23.

The cathode 32 is surrounded by a cylindrical accelerating electrode or grid coaxial therewith and including a plurality of equally spaced linear conductors or wires 38 mounted parallel to one another and to the cathode. The conductors 38 extend. through aligned apertures in the insulating discs 21, 29 and 30 and are electrically connected to one another by a metallic band or collar 39 seated upon the insulating disc 30. One of the conductors may be connected to one of the terminal prongs 23 through a leading-in conductor 4|] embedded in the press 24.

The accelerating electrode or grid 38 is encompassed by a control electrode or grid, preferably coaxial therewith, which comprises a plurality of parallel, linear conductors or wires 4| each of which, as shown clearly in Fig. 2, is in radial alignment with the cathode 32 and alternate of which are in alignment also with a cor-- responding one of the wires 38 of the inner or accelerating grid. The conductors or wires ll extend through aligned apertures in the insu-' lating discs 21, 29 and 30 and are connected together electrically by a metallic band or collar 42 seated upon the insulating disc 30. Suitable potentials may be applied to the control electrode through a leading-in conductor 43 connected to one of the conductors or wires 4| and to one of the terminal prongs 23.

The control electrode or grid 4| encompasses an anode, coaxial therewith, which comprises a plurality of equally spaced parallel, linear rods or wires 44'. The anode wires or conductors 44 extend through aligned apertures in the insulating discs 21, 29 and 30 and are electrically connected by a metallic band or collar 45 seated upon the disc 3!]. The anode may be coupled to an external circuit through a leading-in conducto-r 46 connected to one of the terminal prongs 23 and to one of the conductors or wires 44.

The control electrode or grid may be encompassed in turn by an auxiliary electrode having a cylindrical portion 41 and diametrically opposite flanges 48 which may be secured, as by welding. to the uprights or supports 25. The auxiliary electrode 4! may be connected directly to the cathode by a conductor 54.

As will be seen clearly fromFigs. 2 and 3, each of the elements 44 of the anode has cooperatively associated therewith three elements 4| of the control electrode or grid, which lie in an arcuate boundary, indicated by the dotted line A, partially encompassing the correspondingv anode element 44 and preferably coaxial with the oathode. The device, then, includes in effect six sections of electrodes electrically connected in parallel. v

In a specific embodiment, the grid and-anode elementsmay be rodshaving a diameterof 0.015", the cathode may have a diameter of 0.067, and the elements may be spaced so that the electrode spacings are as follows: I

Radius,

inch Accelerating electrode to axis 0.065 Anode to axis 0.125 Control electrode to axis 0.185 Cylindrical plate to axis 0.250

During operation of the electron discharge device illustrated in Figs. 1 to 3, inclusive, as shown in Fig. 4, an input circuit including a network 49 and a source, such as a battery 50, for applying An output circuit 5| may be con-- anes-p79 it is at a positive. potential, lowerhtha'n the an ode potential, with respect'to the'cathode.-. Pref-e erably, "the fixed potentials applied to the'several electrodes are such that the electrons emanating from the cathode are concentrated in'circula-r 'or .elliptical paths about the anodewires Hi. .The auxiliary electrode 41, nOlLShOWIi-ill Fig. Jamey be connected directlj to the cathodeas described hereto-fore and operated at cathode potential.

When the electron discharge device illustrated in Figs. 1 to 3, inclusivais connected in'circuit as shown in and the anode and acoelerat ing electrode are maintained at positive potentials with respect to the cathode (for example, 125;

volts and 4.0 volts, respectively, in the specific embodiment described hereinabove) it has been found. that the anode current varies with respect to negative control electrode or grid potential in themanner shown by curve-B inFig'. 5.- From this curve it will be seen that as the potential upon the control electrode or. grid is made less negative, the anode current decreases.

At the value of anode potentials given, as indicated by the point-C onthe anode current-anode voltage characteristic D in Fig. 6 (the control electrode being biased at 5.5 volts negative with respect to the cathode), the anode resistance (RA) is positive. Hence, there being a negative I transconductance (Sea) as indicated by the slope of the curve B in Fig. 5,'the amplification fac tor (,IL) necessarily is negative.

may be noted that forthe potentials and param- Specifically, it

etcrs given hereinabove, at an anode potential indicated by point 'C (125 volts), the anode resistance is approximately 10,000 ohms, positive,

and the amplification factor is substantially 16, negative. Hence, the .mutual conductance is sub stantially 400o 10 mhos, negative.

If the anode potential is'increased and the grid and accelerating electrode .potentials are. held constant, it has been'found that, asindicated by iii) tive.

the portion F of curve D,the anode resistance becomes negative for a range of anode potentials,

and then becomes positive again as indicated by the portion G of the curve D. Inasmuch as the anode is highly positive with respect to theoth'er electrodes of the device, it may be pointed out that this negative resistance is not attributable to secondary. electron'emission fromthe anode.

If the anode is held at a constant potential in the range wherein a negative anode resistance obtains, the anode current varies-with the potential of the control electrode or grid as indicated by the curve H in Fig. 5 from which it will be seen that the transconductance, is negative. Hence, the amplification factor is positive. Specifically, for an anode potential of 138 volts, a negative controlelectrode potential of 5.5 volts, and a positive-accelerating electrode potential. of

'4 volts, the anode resistance of the device described aboveis about L000 ohms negative and the amplification factor is substantially 40, posi- Hence, the transconductance .is approxi-v mately 10,000xl0- ,mhos,- negative.

It may be pointed out that when the potentials upon the electrodes of the electron discharge 'device are such that the anode resistance is positive, the load resistance may beselected in the usual manner to attain a desired efficiency. However, Whenthe potentials are such that the anode resistance-is negative, theinsertion ofa small positive resistance in the load oroutput circuit, in series with. the negativeanode resistoperating potentials may 'be necessary. a:

. i l feet obtains throughout a relativelywide range of control electrode or grid potentials.

. 3 ance, reduces the resultant negative resistance and increases the apparent negative transcon duct'ance of the device. Hence, special determi nation of the load resistance for the particular In the embodiment of this invention illustrated in Figs. '7, 8 and 9, theform, number and arrangement of the cathode, auxiliary electrode,

and the various linear electrode elements are the same as that in the embodiment shown in Fig, 1. Certain of. the elements, however, are associated difierently electrically. In Figs.-7, 8 and 9,,the elements of the electrode structure corresponding mechanically orelectrically to those in the embodiment shown inFig. l are designated b'y'the corresponding reference numeral increasedrb-y 10.0. I I I As shown in Fig.1 the electrode structure includes anadditional insulating spacer I55, such as *a, mica disc, maintained in parallel relation to the insulatingspacer I27 by metallic clips: I28. afiixed to the uprights I25. Mounted uponthe insulating spacer I55 is a metallic collar 'or band 0 nected, either internally or externally'of thetenclosing. vessel, to thenext inner members,v as, indicated-by the connection I42, M5 in Fig. 8, and constitutethe elements MI of the control electrode or'grid, mounted at the apices of the angles, of a rsix pointed star-shaped boundary. ,.-The auxiliary electrode I41 .is connected totheelementsi MI by a tie wire IHl andconstitutesa part of the control electrode ofythedeviceu Each of theanode'elements' It'll. has cooperatively asso- 3 ciated therewith three of, the elements. MIjof-the controlelectro'de 01' grid, which lie in an 'arcuate boundary, indicated by the dotted line A in Fig. 9, partially encompassing the corresponding anode element IM. 1 The radius of the boundary A may beapproximately equalto thedistance elements M4. I

The-jelectron discharge device illustratedin Figs, 7, 8 and 9 may be connected in circuit as shown in Fig. 4. "Iheelectrode parameters may be substantially the same as'those-given herein-' above for the-specific embodiment of; the device illustrated in Fig. 1. When thus-connected, and

with the anode and acceleration electrode maintained at constant positivepotentials', "for ex ample, 'theanode at a' potential of 230 volts and theqaccelei'ation electrode-at a potential of '16 9+ between the centers of thecathode Itzfand anode Iii)- volts,; the anode current varies with theflcontrol electrode or grid voltage as-indicated bythe illustrative curve in'Fig: 1%). As will be apparent irom this curve, -the ,transconductan'c'e of the electrondischarge device. is alternately positiveand negative as indicated by the portions- J and-"J and K and K? respectively. At points X and "X corresponding, respectively to negativercontrol electrode potentials of 8.5 and 3.5 volts, thetransconductance may he'- otthe .order of 700x10- mhos, negative, and the anode resistance'may be negative andl-AOO ohms, and 33,000 ohms, respecitively. Theamplificationfactor, then'is Q positive, "at the point X and 23, positive, 'at'-the point X a 'From Fig. 10 it will be apparent that if the variable potentials'impre'ssed upon the control electrode or grid by the input circuit 49 are of suflicient magnitude to embrace the region including J, X and X each pulse or swing of the input potential will produce at least four pulses'in the output current so that in efiect a frequency quadrupling is obtained. The magnitude and frequency of the output current will be dependent,

of 'course, upon the electrical and mechanical I parameters of the electron discharge device.

7 The negative transconductance, with either positive or negative anode resistance, may be obtained also by 'connecting the various elements of the electron discharge device shown in Fig. '7 in the manner illustrated in Figs. 11 and 12. In these figures the elements corresponding mechanically or electrically to those'of the embodiment illustrated in Figs. 7, 8 and 9 are designated by the same characters as in the latter, increased by 100.

As shown in Figs. 11 and 12, the anode-comprises alternate of the outermost linear members 244-electrically connected by the collar or band 256 and the control electrode or grid comprises the other outermost linear members 24l electrically connected by the collar or band 245. The grid composed of the intermediate linear members 260, connected by the collar or band 2.62, is connected directly to the cathode 232 by the conductor 254.

The elements 24| lie at the corners of a regular hexagon and each successive two of them lie in an'arcuate boundary; indicated by the dotted line A in Fig. 12, partially encompassing the corresponding anode element 244, are equally spaced from such anode element, and'are spaced the same distance from the cathode 232 as the anode elethe parameters thereof may be the same as those given heretofore for the specific embodiment of the device'illustrated in Fig. 1. When thus operated and with constant positive potentials upon the anode and accelerating electrode, for example, 100'volts' and 14 volts, respectively, the anode current varies with the negative control electrode voltage as indicated by the. curve M in Fig. 13, from which it will be apparent that a negative trarisconductance obtains throughouta relatively wide range of control electrode potentials. .If the control electrode is maintained at a fixed negative potential, for example 6 volts, and the accelerating electrode is maintained positive, for example 14 volts, the anode current varies with anode potentialas indicated by the curve N in Fig.'14, from which it will be seen that the anode resistance is, positive. Hence, the amplification factor is negative; for example, at the values of potential given, that is if anode voltage equals 100 volts, control electrode potential equals '6 volts and accelerating electrode potential equals 14 volts, the amplification factor may be 6.5 negative, and the transconductance 500 10 mhos,

, negative;

If the control electrode is maintained at a fixed potential, for example 6 volts negative, and the accelerating electrode is made less positive, for example 9 volts, the anode current varies with anode voltage as indicated by the curve 0 in Fig. 14,'from which it will be seen that for a range of anode voltages, the anode resistance is negative. If the anode potential is maintained at 'a fixed value in this range, for example 100 volts, the anode current varies with control electrode potential as indicated by the curveP in Fig. 13. At the pointY on this curve, corresponding to a negative control electrode potential of 6 volts and a negative [anode resistance of 25,000 ohms, the transconductance is about 500 10 mhos, negative, and the amplification factor is approximately 12.5 positive.

It willbe apparent. from Figs.l3 and 14 that in the device illustrated in Figs. -11 and 12, a negative transconductance, with either a positive anode resistance and negative amplification factor or a negative anode resistance and positive ratus constructed in accordance with this invention may be utilized advantageously in a variety of applications. In addition to the application in frequency multiplying systems mentioned heretofore, the invention may be utilized, for example, in amplifiers, with or without negative feedback, in detectors or in oscillators.

Although specific embodiments of this inventrode. an anode including a linear electron receiving element, said control electrode including spaced linear elements mounted about said electron receiving element, an input circuit connected to said cathode and said control electrode, and an. output circuit connected to said cathode and said anode including means applying such posh tive potentials to said anode and said accelerating electrode that the anode current varies inversely with increments in the anode potential in .the absence of secondary emission from said anode.

2. Electron discharge apparatus comprising a cathode, a linear anode parallel to said cathode, an accelerating electrode between said cathode and said anode, a'control electrode including a pair of linear elements on opposite sides of said anode, an input circuit connected to said cathode and said control electrode including means for applying a negative bias to said control electrode,

. means for applying a positive potential to said accelerating electrode, and an output circuit connected to said cathode and said anode including means for maintaining. said anode at a positive potential higher-than the potential of said accelerating, electrode, said bias and said anode and accelerating electrode potentials being such that the anode current varies inversely with incretrode including a plurality of linear elements disposed about said accelerating electrode and in cooperative relation with said electron receiving elements, an input circuit connected between said cathode and said control electrode, means applying a positive potential to said accelerating electrode, and an output circuit connected between said cathode and said anode including means maintaining said-anode at a positive potential higher than the accelerating electrode potential, said positive potentials being such that throughout a range of increments in the anode potential the current in said output circuit varies inversely with anode potential.

5. Electron discharge apparatus in accordance with claim 4 wherein said anode and control electrode elements are mounted parallel to one another and said cathode and are substantlall equally spaced from said cathode.

6.- Electron discharge apparatus comprising a cathode, an anode, and a control electrode including a plurality of linear elements mounted 8. Electron discharge apparatus comprising a cathode, a linear anode in alignment with said cathode, an accelerating electrode including a linear member between said cathode and said anode and in alignment therewith, and a control electrode including linear members on opposite sides of said anode.

9. An electron discharge device comprising a linear cathode, a linear anode in alignment with said cathode, an accelerating electrode including a linear member between said cathode and said anode and in alignment therewith, and a control electrode including a member between said accelerating electrode and said anode and in alignment therewith and other members on opposite sides of said anode.

10. An electron discharge device comprising a cathode, a rod anode in alignment with said cathode, and a control electrode including a plurality of linear elements parallel to said cathode, at least two of said elements being spaced from said cathode a distance substantially equal to the spacing between said cathode and said anode and disposed on opposite sides of said anode.

11. Electron discharge apparatus comprising a cathode, an anode in alignment with said cathode, and a control electrode including alinear member in alignment with said cathbde and said anode and other members equally spacedfrom and on opposite sides of a line passing through said cathode and the center of said anode.

12. Electron discharge apparatus comprising a cathode, an anode including a plurality of linear electron receiving elements mounted about said cathode, and a control electrode including a plurality of linear members between said cathode tween said electron receiving elements.

' 13."Electron discharge apparatus comprising a cathode, an anode including a plurality of linear elements mounted in a cylindrical boundary about said cathode, and a control electrode including a plurality of linear elements mounted in a cylindrical boundary between'said cathode and said first boundary, each of said second elea plurality of electrode elements'mounted in a cylindrical boundary about said first boundary,

means electrically connecting one group of alternate of said second elements to said first electrode elements, means electrically connecting the other alternate of said second elements, an input circuit connected to said cathode and saidfir'st electrode elements and said group of second elements, and an output circuit connected to said cathode and said other alternate second elements;

16. Electron discharge apparatus in accordance with claim 15 comprising means included in said output circuit for maintaining said other elements at a positive potential, and means in'said input circuit applying such negative potentials to said first electrode elements and the group of said second'elements connected thereto that the current in said output circuit increases as said negative potential increases. 17. Electron discharge apparatus in accordance with claim 15 comprising an accelerating elecanode, and including spaced elements in an arcuate boundary about said anode. I

19. Electron discharge apparatus comprising a cathode, an anode comprising a plurality of linear elements mounted in a cylindrical boundary about said cathode, a control electrode comprising a plurality of linear elementsmounted in a cylindricalboundary about said first boundary,

said first and'second elements being substantially.

parallel to one another and to said cathode,'an

1 input circuit connectedto said cathode and said control electrode, and an output circuit connected to saidcathode and sai-danode. I

20. Electron discharge apparatus comprising a cathode, a linear anode in alignment with said cathode, anda control electrode including linear elements mounted in an arcuate boundary passing between said cathode and said anode and an ele ment mounted outside of said anode and electrically connected to said linear elements.

EDMOND BRUCE. I

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