US2073599A - Electric discharge device - Google Patents

Electric discharge device Download PDF

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Publication number
US2073599A
US2073599A US4049A US404935A US2073599A US 2073599 A US2073599 A US 2073599A US 4049 A US4049 A US 4049A US 404935 A US404935 A US 404935A US 2073599 A US2073599 A US 2073599A
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United States
Prior art keywords
electrodes
electrode
potential
electrons
multiplying
Prior art date
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Expired - Lifetime
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US4049A
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English (en)
Inventor
Malter Louis
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RCA Corp
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RCA Corp
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Publication date
Priority to BE414089D priority Critical patent/BE414089A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US4049A priority patent/US2073599A/en
Priority to FR801041D priority patent/FR801041A/fr
Priority to GB2586/36A priority patent/GB469477A/en
Application granted granted Critical
Publication of US2073599A publication Critical patent/US2073599A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers

Definitions

  • invention relates to electric discharge devices and more particularly to devices of the type wherein amplification of a primary electron stream, such, for example, as is emitted from a thermionic cathode or from a photo-sensitive surface exposed to light, is accomplished through utilization of the phenomenon of secondary emission.
  • an electrode If an electrode is subjected to electron bom- 10 bardment', it will emit secondary electrons.
  • the ratio of the number of secondary electrons to the number of primary electrons depends, in'part, upon the character of the surface and upon the potential difference between the surface and the source of the electrons. This ratio can be made considerably greater than unity.
  • a ratio of three or more secondary electrons to one impinging electron is readily obtainable with metallic surfaces treated in known ways and subjected to discharges at potentials of 300 to 400 volts. Since the emitted electrons exceed the impinging electrons in number, the electrodes emitting them, hereinafter, will occasionally be referred to as multiplying electrodes.
  • the ratio of secondary emission from the second multiplying electrode may also be greater than unity.
  • n multiplying electrodes in cascade for example, an amplification of the original or primary electron current equivalent to the amplification per electrode raised to the nth power. A million-fold amplification has been obtained in a single device.
  • the accelerating electrode and the multiplying electrode are entirely distinct and, consequently, it is possible to set the value of the accelerating field-independent of the-potential with which electrons strike a multiplying electrode.
  • the magnitude of the current which may be drawn from any multiplying electrode is determined only by the potential of the electrode directly above itself and increasing this potential exercises practically no effect upon the amplification obtained in the succeeding stage.
  • an object of my invention to provide an electric discharge device, utilizing secondary electron emission, wherein maximum gain per stage is obtained and linearity exists between input and output.
  • Another object of my invention is to provide a secondary electron amplifier or.multiplier'which is eflicient and reliable in operation and in which v the amplification obtainable is very great as compared with the amplification obtainable with a thermionic amplifier of the usual type.
  • Another object of my invention is to provide a device of the type described that may be used for substantially any purpose for which thermionic tubes of present types are, used, such, for example, as an amplifier, a demodulator, an oscillator, a combined oscillator and modulator, etc;
  • Another object of my invention is to provide a combined phototube and amplifier that shall be responsive to the very highest frequencies encountered in television transmitting apparatus.
  • a still further and more specific object of my invention is to provide a device of the type de-- scribed that lends itself readily to mass production methods.
  • I utilize a' single magnetic field for concentrating and directing all of the electron streams to the proper target electrodes, whereby the major portion of each secondary electron stream is utilized and the primary electrons are prevented from being drawn past the targets to impinge directly upon the output electrode.
  • my improved electric discharge device is constituted by an evacuated container, preferably, though not necessarily cylindrical, wherein are disposed a plurality of sets of discrete electrodes, the electrodes lying in spaced apart planes parallel to each other and to the long axis of the container.
  • the container in which the electrodes are mounted does not have to be oriented in any particular mannerduring operation, I find it convenient to style the multiplying electrodes as lower and the electrodes opposite to them, either as upper or accelerating electrodes. It has been found that good results are obtained if the multiplying electrodes are provided with a photo-sensitive surface.
  • Means are provided for impressing suitable potentials on the electrodes and for establishing a magnetic field which threads the container, the lines of force being parallel to the electrode faces and transverse to the long axis of the device.
  • Figure l is a view in perspective of an electric discharge device constructed according to my invention, portions of the container wall and the 60 associated magnetic field structure being broken away to more clearly illustrate the disposition of the electrodes, R I
  • Fig. 2 is a view of an analogous device constructed according --to my invention, wherein the 65 source of primary electrons is thermionic and wherein a grid is provided to control the electron flow therefrom,
  • Fig. 3 is a diagrammatic sectional view of the cathode and control element in the device shown 70 in Fig. 2,
  • Fig. 4 is an end view of the device shown in Fig. 2 looking toward the left, illustrating my preferred means for establishing a magnetic field parallel to theelectrode surfaces,
  • Fig. 5 is a'diagrammatic view exemplifying the ing the electrode firmly in position.
  • Fig. 6 is a diagrammatic view illustrating the manner in which the device shown in Fig. 2 is operated
  • Fig. 7 is a diagrammatic view of an alternative deviceconstructed according to my invention.
  • Fig. 8 is an end view of the device shown in Fig. 7, and r Figs. 9 and 10 are graphs exemplifying certain characteristics of my improved-device.
  • a preferred embodiment of my invention is constituted by a cylindrical, evacuated container I of glass or Pyrex wherein is disposed a plurality of photo-sensitive lower electrodes 3, lying in the same plane and spaced apart along the long axis of the container and a plurality of upper or accelerating electrodes 5 disposed in a plane parallel to and spaced from the plane in which lie the first mentioned electrodes.
  • the lower electrodes are preferably made of silver and the upper electrodes of molybdenum, tantalum, nickel, or any other metal which is easily de-gassed and not easily oxidized.
  • the upper and lower electrodes are grouped, vertically, in pairs. All of the electrodes have substantially the same dimensions and they are spaced apart substantially the same distance along the long axis of the container. Such configuration is desirable in that it permits accurate electron-path-control by means of a single magnetic field.
  • Each cross rod has a lead l5 welded thereto, which lead extends through the wall of the container to the exterior thereof.
  • Each lower cross-rod (not shown) is also provided with an output lead H.
  • An output electrode I9 is mounted in one end of the tube, preferably fairly closeto the sets of electrodes and in a plane transverse to the tube axis.
  • the output electrode is provided with a terminal connection 2
  • the several sets of electrode sub-assemblies and the output electrode are first suitably mounted in the container which is then heated and evacuated.
  • the container is next baked for about ten minutes at a temperature of 210 C. which causes the alkali metal to combine with the silver oxide, thus giving rise to a highly photosensitive surface. During the baking step the excess caesium is pumped out of the device.
  • any caesium or other alkali metal which is deposited upon the upper electrodes or upon the container forms a relatively stable compound with the excess caesium and prevents it from being redeposited on the inner walls of the container where it would provide leakage paths between the electrodes.
  • any convenient means may be utilized for estab-' lishing a magnetic field parallel to the electrode surfaces, such, for example, as the device partially shown in perspective in Fig. 1 and in end elevation in Fig. 4.
  • this device is constituted by an U-shape element 23 of magnetically permeable material on which is mounted an energizing coil 25 and to each upstanding portion of which is afilxed a plate 21, also of permeable material.
  • the tube is disposed between these plates in such position that a substantially uniform magnetic field is set up parallel to the opposed surfaces of the sets of .electrodes.
  • a permanent magnet may be substituted for the electromagnet shown, or the tube may be disposed within a coil of wire carryingan electric current.
  • the first lower electrode 3 at the left, farthest from the output electrode l9,' may be connected to the negative terminal of a source of unidirectional potential, exemplified in the drawings by a resistor, and. the output electrode may be connected to the positive terminal of the source through an output device such as a resistor 3
  • the next adjacent electrode 3, or first multiplying elec-' trode may be connected to apoint 33 on the resistor somewhat more positive and each of the remaining multiplying electrodes 3 connected to successively more positive points 35 and 31 on the resistor.
  • the first upper accelerating electrode 5, paired with the first lower photo-sensitive electrode, may
  • the direction of the component depends upon the polarity of the field. If the electric anrl magnetic fields are adjusted to proper values, the electrons will describe trochoidal paths and will strike the first multitribution, the maximum velocity being determined by the color and the nature of the light and upon the work function of the emitting surface.
  • the photo-electrons are emitted in all directions. Nevertheless, by reason of the presence of the magnetic field, the electrons emitted from a single point, even with varyingvelocities which differ by considerable amounts from zero, will be focussed to substantially a single corresponding point on the next succeeding electrode.
  • a thermionic primary electron source instead of a photo-electric source, for the purpose of rendering my improved device capable of uses to which well-known thermionic tubes are put.
  • a controllable electron source is substituted for the first lower photo-sensitive electrode shown in Fig. 1.
  • the electron source may be constituted by a metallic thimble 49,,the upper end of which has a layer of electron emissive oxides 50.
  • the thimble is completely surrounded and shielded by a cylindrical metallic grid structure 5
  • the upper face of the cap lies in the plane of the multiplying electrodes 3 and, preferably, the perforation therein is coaxial with the emitting portion of the cathode, and is covered by a fine screen 55 to which it is electrically connected.
  • This grid structure when supplied with proper potentials, either direct or fluctuating, serves to control the emission from the thermionic cathode in the same way as emission from the first photo-sensitive lower electrode 'in the device shown in Fig. 1 is caused to be con-.
  • Fig. 6 of the drawings the potential distribution on the various electrodes and the cathode of the tube shown in Fig. 2 may be the same as that exemplified by Fig. 5.
  • any desired input circuit elements may be connected between the grid and the cathode of the tube, exemplified in the drawings by an input resistor 51, a grid biasing potential source 59 and potential divider 6
  • FIGs. 7 and 8 A still further modification of my invention is shown in Figs. 7 and 8.
  • the device'illustrated corresponds in function to the device shown in Fig. 1.' It differs from that device, however, in that the upper, set of accelerating electrodes is replaced by a single film 63 of resistive. material and the lower set of photo-sensitive electrodes is replaced by a similar film of resistive material which has been photo-sensitized.
  • These resistive films may be formed by sputtering a metal film onto a strip of a non-conductor, such as mica, or in any other desired manner.
  • an external source 61 By means of an external source 61 the two' ends of the lower film 65 are maintained at different potentials. In the same manner a potential difference is maintained between the two ends of the upper film 63, by a suitable potential source 69 connected thereto. The negative terminal of each source is connected to the left end of the corresponding film as it appears in the drawings, thus making the said left ends at lower potentials than the right ends.
  • a further external source H By means of a further external source H the left end of the upper film electrode is maintained at a higher potential than the left end of the lower electrode. This automatically insures'that each point on the upper electrode is at some potential above the point on the lower electrode immediately beneath it.
  • the final output current from an electric discharge device, constructed according to my invention, in addition to being proportional to the number of electrons emitted from the primary source, is also dependent upon the potential of any one of the multiplying electrodes with respect to the next adjacent electrode which is normally maintained at a lower potential.
  • any one of the multiplying electrodes with respect to the next adjacent electrode which is normally maintained at a lower potential.
  • the device shown in Fig. 2 of the drawings may also be made to oscillate in the manner just described or oscillations may be obtained by replacing the input and output resistors, shown in Fig. 6, by suitable inductors coupled to. each other magnetically in proper phase. means may be employed, if desired, for feeding back a portion of the output energy to the input circuit. 4
  • Either of the devices shown in Figs. 1 and 2 may be utilized as combined modulator-oscillators by introducing the modulatingpotentials into a lead which supplies potential to one of the multiplying electrodes while it is in the oscillatory state.
  • An electric discharge device constructed and operated according to my invention has many advantages.
  • the spacechargelimitations of prior devices are avoided.
  • the efiiciency thus obtained is much greater than.- where dependence is placed solely upon electrostatic-fields between adjacent electrodes for the purpose of both accelerating the electrons and directing them to the secondary emitters.
  • the potential gradient which is favorable to the escape of the emitted electrons is adverse to and acts as a retarding field for the impinging electrons.
  • the impinging electron stream is concentrated and directed to the emitting surface and, at the same time, there is maintained at the surface an electrostatic potential gradient which is favorable for removing the emitted electrons with maximum eificiency.
  • Substantiallyno interference or interaction between the high velocity impinging electrons and the low velocity secondary electrons has been observed and it seems highly probable that the magnetic field causes the emitting electrons to move out of the stream of impinging electrons as soon as the emitted electrons attain any substantial velocity.
  • the outputcurrent is not limited by space-charges.
  • my improved device has no saturation point, the amount of output current which it can provide being dependent only upon the amount of heat which the electrodes can dissipate and upon their resistance to destructive electrostatic forces, the potentials applied to the electrodes and the strength of the magnetic field.
  • An electric discharge device comprising an elongated container, at strip of insulating material mounted in a plane parallel to the long axis of the container, a pair of spaced apart sets of discrete electrodes, the electrodes of one set being paired with the electrodes of the other set, the electrodes of one set being supported in substantially uniform spaced apart relation on said insulating strip and presenting their electrode surfaces entirely exposed to the electrodes of the other set.
  • An electric discharge device constituted by an elongated container in which are disposed a plurality ofsets of'spaced apart discrete electrodes, the electrodes of one set being paired with the electrodes of the other set and the electrodes of each set being substantially uniformly spaced apart along the long axis of the container, the container being provided with an angularly dis posed depending portion in which is supported a primary-electron source, and control means for said source disposed in a plane substantially parallel to the plane in which lies one of the said sets of electrodes.
  • An electric discharge device constituted by ,an elongated container in 'which ;are disposed a plurality of setsof spacedapart discrete electrodes, the electrodes of one set being paired with the electrodes of the other set and the electrodes oi each set being substantially uniformly spaced apart along the long of the container, the container being provided. with an singularly dls posed depending portion in which is supported a thermionic electron source, and control means for said source disposed in a plane substantially parallel to the plane in which lies one of the said sets of electrodes.
  • An electric discharge device comprising an elongated container, a pair of insulating strips.
  • a pair of spaced apart sets of discrete electrodes mounted in parallel planes on opposite sides of the long axis of said container, a pair of spaced apart sets of discrete electrodes, the electrodes of one set being paired with the electrodes of the other set, the electrodes of one set being supported in substantially uniform spaced apart relation on one of said strips and the electrodes of the other set being supported in similar, array on the other of said strips, the electrodes of one set presenting their electrode surfaces entirely exposed to the electrode surfaces of the other set.

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  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Particle Accelerators (AREA)
  • X-Ray Techniques (AREA)
  • Electron Sources, Ion Sources (AREA)
US4049A 1935-01-30 1935-01-30 Electric discharge device Expired - Lifetime US2073599A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE414089D BE414089A (en)van) 1935-01-30
US4049A US2073599A (en) 1935-01-30 1935-01-30 Electric discharge device
FR801041D FR801041A (fr) 1935-01-30 1936-01-21 Dispositif à décharge électrique
GB2586/36A GB469477A (en) 1935-01-30 1936-01-27 Improvements in or relating to electron discharge devices

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US4049A US2073599A (en) 1935-01-30 1935-01-30 Electric discharge device

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US2073599A true US2073599A (en) 1937-03-09

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US4049A Expired - Lifetime US2073599A (en) 1935-01-30 1935-01-30 Electric discharge device

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BE (1) BE414089A (en)van)
FR (1) FR801041A (en)van)
GB (1) GB469477A (en)van)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2417805A (en) * 1941-04-30 1947-03-25 Int Standard Electric Corp Electric oscillation generator and amplifier
US2420753A (en) * 1943-11-10 1947-05-20 Hazeltine Research Inc Wave-signal translating system
US2423998A (en) * 1943-04-30 1947-07-15 Farnsworth Television & Radio Electron discharge device
US2428612A (en) * 1942-05-09 1947-10-07 Gen Electric Magnetron
US2444242A (en) * 1942-05-09 1948-06-29 Gen Electric Magnetron
US2520152A (en) * 1943-11-18 1950-08-29 Farnsworth Res Corp Radiant energy receiving device
USD942534S1 (en) * 2019-10-19 2022-02-01 Mahdi Al-Husseini Calculator with electronic tube display and keypad

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE767612C (de) * 1936-07-30 1953-01-05 Aeg Anordnung zur Verstaerkung eines Elektronenbildes durch Sekundaerelektronenemission
NL50859C (en)van) * 1937-03-30 1941-08-16
DE762710C (de) * 1939-03-18 1954-01-11 Telefunken Gmbh Elektronenvervielfacher mit als feinmaschige Netze ausgebildeten und durch Aufdampfen einer aktivierenden Substanz aktivierten Prallelektroden

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2417805A (en) * 1941-04-30 1947-03-25 Int Standard Electric Corp Electric oscillation generator and amplifier
US2428612A (en) * 1942-05-09 1947-10-07 Gen Electric Magnetron
US2444242A (en) * 1942-05-09 1948-06-29 Gen Electric Magnetron
US2423998A (en) * 1943-04-30 1947-07-15 Farnsworth Television & Radio Electron discharge device
US2420753A (en) * 1943-11-10 1947-05-20 Hazeltine Research Inc Wave-signal translating system
US2520152A (en) * 1943-11-18 1950-08-29 Farnsworth Res Corp Radiant energy receiving device
USD942534S1 (en) * 2019-10-19 2022-02-01 Mahdi Al-Husseini Calculator with electronic tube display and keypad

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Publication number Publication date
BE414089A (en)van)
GB469477A (en) 1937-07-27
FR801041A (fr) 1936-07-25

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