US2135615A - Multipactor - Google Patents

Multipactor Download PDF

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Publication number
US2135615A
US2135615A US63424A US6342436A US2135615A US 2135615 A US2135615 A US 2135615A US 63424 A US63424 A US 63424A US 6342436 A US6342436 A US 6342436A US 2135615 A US2135615 A US 2135615A
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US
United States
Prior art keywords
cathode
cathodes
electrons
shield
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US63424A
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English (en)
Inventor
Philo T Farnsworth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Farnsworth Television Inc
Original Assignee
Farnsworth Television Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Farnsworth Television Inc filed Critical Farnsworth Television Inc
Priority to US63424A priority Critical patent/US2135615A/en
Priority to GB1069/37A priority patent/GB487610A/en
Priority to DEF4475D priority patent/DE971006C/de
Priority to FR817748D priority patent/FR817748A/fr
Application granted granted Critical
Publication of US2135615A publication Critical patent/US2135615A/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
    • H01J43/30—Circuit arrangements not adapted to a particular application of the tube and not otherwise provided for

Definitions

  • My invention possesses numerous other objects and features'of advantage, some of which, to-
  • Figure 1 is a view showing a preferred embodiment of the multipactor tube of this invention I in longitudinal cross section.
  • Figure 2 is a similar view, partly in elevation and partly in section, showing schematically the external connections of the device as used as a detector-amplifier in a radio receiving circuit.
  • Figure 3 is a diagrammatic representation of the fundamental circuit of the multipactor itself, with such external circuit elements as are necessary for an explanation of the operation.
  • the multipactor of this invention comprises a primary cathode from which initial electrons are emitted, these electrons being directed at a series of foraminated secondary cathodes which are capable of emitting secondary electrons at a ratio to impacting primaryelectrons which is greater than unity.
  • Means are provided for maintaining a substantially uniform or increasing potential gradient along this series of secondary cathodes, each acting as an anode to the preceding cathode in the series, and means are also provided for collecting the electron fiow from the last cathode of the series.
  • the primary cathode should be photo-emissive rather than thermionic.
  • This arrangement may be better understood by reference to the preferred form of the device shown in the drawings, wherein the reference character I refers to a tubular vitreous envelope which is evacuated to as high degree as is practical. This tube is symmetrical, and sealed through each end is a lead 2, 2' which is connected to a primary cathode 4, 4'.
  • These cathodes may conveniently be-madeof silver, and provided with photo-electric surfaces of the well known silver-oxide-caesium type.
  • each of these cathodes is foraminated, the ratio of their over-all area. to the combined area of the foraminations being preferably of the order of 3 or 4 to 1.
  • the cathodes may be made of sheet material and the openings punched therein, or they may be made of fine meshed screen suitably supported, as is shown in the drawings, the latter construction being somewhat preferable.
  • the material of their construction is preferably silver and they are provided with silver-oxide-caesium surfaces which render them photoelectric and also capable of emitting secondary electrons at a ratio to impacting primaries of 6 to 8. His of some slight advantage if the holes. through the cathodes are not alined, but as will be shown later, this is of relatively small importance as regards the over-all efiect of the device.
  • the first secondary cathode 6 and the last secondary cathode l3 are provided with leads l5 and I6, respectively. It is also convenient for some purposes to provide individual leads II for the intermediate cathodes I to l2.
  • the interior wall l9 of the tube l is metalized between the cathode 6 and the cathode l3, so that the tube itself forms a hollow resistor 50 with the secondary cathodes in electrical contact therewith.
  • the shields 5 and 5' should, be insulated from this metalized surface. Any of the well known conducting coatings may be used, a coating of nickel which is so thin as to be transparent being quite suitable for the purpose, and from the standpoint of power conservation it is desirable that the resistance between the cathodes 6 and I3 be of the order of from 50,000 ohms to 1 megohm. These are not limiting values, however.
  • the fundamental circuit device as ordinarily used is shown in Figure 3.
  • the signal voltage which may be considered as supplied across the tuned circuit 20, is supplied to the cathode 4, and the shield 5 is grounded.
  • supplies to the secondary cathode l3 a positive potential with respect to ground.
  • the impedances 22 represent the resistive coating on the inside of the tube, or, when this is absent, they may be connected externally as shown.
  • the cathode 4 be illuminated from a source of light 21, photoelectrons will be emitted therefrom, and will pass through the electrostatic shield 5 to impinge upon the secondary cathode 6.
  • these electrons will be traveling at relatively high velocity and a proportion of them will impact the cathode while others will pass through it, the relative numbers being almost exactly in the ratio of solid area to open area in the cathode.
  • the cathode be of wire netting, with the spaces between the wires equal'to the diameter of the wire, the proportion intercepted will be almost exactly threefourths.
  • the impacting primaries will release secondary electrons from the cathode 6 at a ratio which is dependent upon their velocity of impact.
  • the secondaries will be of low velocity, and experience has shown that practically all of the released electrons will be drawn through the apertures and accelerated toward the secondary cathode I, where the phenomena of release of secondaries by impact will be repeated.
  • the formation of the cathodes will, in general, cause a strong curvature of the lines of force at the apertures or foraminations, so that it is the exception rather than the rule when an electron travels straight through; in general they will be deflected, and diffused practically uniformly over the succeeding secondary cathode. As far as the number of electrons which impact the successive secondary cathodes is concerned, it therefore makes practically no difference whether the apertures be aligned or not.
  • the amplification at each of the foraminated secondary cathodes is, 4.75.
  • the current amplification up to and including the cathode I3 is 4.75 or something over 244,000.
  • the current in the cathode circuit will be five times this 244,000+, while that to the shield 5' will be six times this value, giving a current amplification of about 1,220,000 or 1,460,000, depending upon whether the output circuit be taken as the circuit of the cathode 4 or that of the shield 5.
  • Either electrode may be used as the output, the two being 180 out of phase, and the desirability of using one or the other electrode as the output circuit depending upon the phase upon which it is desired to use the output signal.
  • the ratio of the current to the collector 5' and that in the circuit of the cathode 4 will always be since the current through the impedance 2G is decreased by that supplied by the electrons impacting on the cathode I.
  • the increase being substantially linear for small voltages and falling on as the voltage increases.
  • Figure 2 shows schematically a method of utilizing the tube in a radio-receiving circuit, the impedances 22 being assumed in this case to be the metalized tube surface.
  • the signalvoltage is supplied from an antenna or radio frequency transmission line 30 coupled to the inductor of the tuned circuit 20.
  • the shield 5, insteadof being connected to ground directly, is connected thereto through a biasing resistor 8
  • the initial velocity of emission of electrons from the cathode 4 will be low and quite uniform, and the number collected by the shield will be very accurately controlled ,by the signal voltage, increasing the efficiency of detection. If white" or mixed radiahence the performance of the device. With a low value of resistance 3
  • the output circuit acts as a detector, maximum detection occurring if the device he so adjusted that maximum current flows in the impedance 26 at zero signal.
  • the initial cathode 4 and shield 5 may be used to supply automatic volume control for the system, the integrating circuit 3l-32 being given a time constant whichis long in comparison with the period of the lowest modulating frequency present in the signal, and the impedance of the circuit being sufilciently low so that the shield will block the emission from the cathode l to only the desired degree.
  • the negative voltage characteristic will cause oscillation in this circuit, and either heterodyne or zero-beat detection may be accomplished with the device. Furthermore it is not necessary that the input be applied at radio frequency, for the apparatus will operate equally well on audible or sub-audible frequencies.
  • a current amplifier comprising an evacuated envelope, *9, primary cathode within said envelope, a series' of secondary cathodes each comprising awoven screen having a surface ca- 1 pable ofemitting secondary electrons at a ratio to impacting primary electrons greater than unity, an electrostatic shield screen positioned between said primary cathode and said secondary cathodes, and means for collecting the electrons emitted from the lastsecondary cathode of said series, said shield screen having a mesh larger than the mesh of said cathodes.
  • An amplifying and detecting tube comprising a photo-emissive cathode, an electrostatic screen of small projected area mounted in front of said cathode, a series of foraminated. secondary cathodes mounted in spaced relationship in front of said screen, each of said secondary cathodes having a surface capable of emitting secondary electrons at a ratio to impacting primaries greater than unity and the foraminations in adjacent cathodes being offset to reduce the probability of an electron emitted from said primary cathode traversing the entire series of seconda'ry cathodes without impacting thereon, and

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Amplifiers (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
US63424A 1936-02-11 1936-02-11 Multipactor Expired - Lifetime US2135615A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US63424A US2135615A (en) 1936-02-11 1936-02-11 Multipactor
GB1069/37A GB487610A (en) 1936-02-11 1937-01-13 Improvements in electron multipliers
DEF4475D DE971006C (de) 1936-02-11 1937-02-10 Schaltung fuer Sekundaerelektronenvervielfacher
FR817748D FR817748A (fr) 1936-02-11 1937-02-11 Multiplicateur d'électrons

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US63424A US2135615A (en) 1936-02-11 1936-02-11 Multipactor

Publications (1)

Publication Number Publication Date
US2135615A true US2135615A (en) 1938-11-08

Family

ID=22049100

Family Applications (1)

Application Number Title Priority Date Filing Date
US63424A Expired - Lifetime US2135615A (en) 1936-02-11 1936-02-11 Multipactor

Country Status (4)

Country Link
US (1) US2135615A (fr)
DE (1) DE971006C (fr)
FR (1) FR817748A (fr)
GB (1) GB487610A (fr)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2558337A (en) * 1945-12-10 1951-06-26 Howard A Chinn Noise generator
DE767107C (de) * 1939-01-19 1951-10-31 Sueddeutsche Telefon App Als Pendelvervielfacher arbeitender Sekundaerelektronenvervielfacher
US2580697A (en) * 1949-06-30 1952-01-01 Bell Telephone Labor Inc Image dissector tube
DE861727C (de) * 1939-06-10 1953-01-05 Sueddeutsche Telefon App Mehrgitterroehre mit Sekundaeremission und ihre Verwendung in einer Schaltung zur Symmetrierung unsymmetrischer Eingangsspannungen
US2702865A (en) * 1949-04-02 1955-02-22 Texas Co Electron multiplier
US2866914A (en) * 1955-12-26 1958-12-30 Schlumberger Well Surv Corp Photomultiplier
US2895068A (en) * 1954-12-14 1959-07-14 Siemens Edison Swan Ltd Photo-electric cells
US3043974A (en) * 1958-03-06 1962-07-10 Nat Res Dev Electron discharge devices
US3299316A (en) * 1963-08-28 1967-01-17 Hughes Aircraft Co Voltage divider network encapsulated in the housing of a storage tube
US3510714A (en) * 1967-05-01 1970-05-05 Research Corp Solar energy converter with trough-shaped cathode and shielded,planar anode
US3574909A (en) * 1965-08-30 1971-04-13 Kurt H Brenner Jr Method of reducing internal matrix arcing in electrostatic printing tubes
US11588421B1 (en) 2019-08-15 2023-02-21 Robert M. Lyden Receiver device of energy from the earth and its atmosphere

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE944873C (de) * 1935-03-07 1956-06-28 Aeg Einrichtung zur Verstaerkung eines Elektronenstromes

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE767107C (de) * 1939-01-19 1951-10-31 Sueddeutsche Telefon App Als Pendelvervielfacher arbeitender Sekundaerelektronenvervielfacher
DE861727C (de) * 1939-06-10 1953-01-05 Sueddeutsche Telefon App Mehrgitterroehre mit Sekundaeremission und ihre Verwendung in einer Schaltung zur Symmetrierung unsymmetrischer Eingangsspannungen
US2558337A (en) * 1945-12-10 1951-06-26 Howard A Chinn Noise generator
US2702865A (en) * 1949-04-02 1955-02-22 Texas Co Electron multiplier
US2580697A (en) * 1949-06-30 1952-01-01 Bell Telephone Labor Inc Image dissector tube
US2895068A (en) * 1954-12-14 1959-07-14 Siemens Edison Swan Ltd Photo-electric cells
US2866914A (en) * 1955-12-26 1958-12-30 Schlumberger Well Surv Corp Photomultiplier
US3043974A (en) * 1958-03-06 1962-07-10 Nat Res Dev Electron discharge devices
US3299316A (en) * 1963-08-28 1967-01-17 Hughes Aircraft Co Voltage divider network encapsulated in the housing of a storage tube
US3574909A (en) * 1965-08-30 1971-04-13 Kurt H Brenner Jr Method of reducing internal matrix arcing in electrostatic printing tubes
US3510714A (en) * 1967-05-01 1970-05-05 Research Corp Solar energy converter with trough-shaped cathode and shielded,planar anode
US11588421B1 (en) 2019-08-15 2023-02-21 Robert M. Lyden Receiver device of energy from the earth and its atmosphere

Also Published As

Publication number Publication date
GB487610A (en) 1938-06-23
DE971006C (de) 1958-11-27
FR817748A (fr) 1937-09-09

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