US2245119A - Electron multiplier circuits - Google Patents

Electron multiplier circuits Download PDF

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Publication number
US2245119A
US2245119A US244061A US24406138A US2245119A US 2245119 A US2245119 A US 2245119A US 244061 A US244061 A US 244061A US 24406138 A US24406138 A US 24406138A US 2245119 A US2245119 A US 2245119A
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Prior art keywords
multiplier
anode
electron
potential
electron multiplier
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Expired - Lifetime
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US244061A
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English (en)
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Walton George William
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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

  • the present invention relates to electron multipliers having secondary electron emitting electrodes int-he form of grids and to circuits therefor.
  • An object of the invention is to provide a method of and means for injecting one or more alternating voltages into the multiplier circuits, so that these voltages will appear in the output circuit of the multiplier.
  • the invention provides a method whereby a carrier frequency can be injected into a circuit of the multiplier, so that the output of the multiplier will consist of a carrier frequency modulated in amplitude in accordance with the intensity variations of the primary electron stream of the multiplier.
  • the method according .to the invention enables a carrier modulation of 100% to be achieved, which is of great importance when the multiplier is employed in a televisiontransmitter.
  • the invention is based upon the following discoveries relating to the properties of such gridelectrode electron multipliers.
  • An electron multiplier comprises a cathode, which may be photo-electric or thermionic, an anode or collecting electrode, and interposed between them a number of secondary electron emitting grid electrodes placed one after the other in the path of the current through the multiplier.
  • the anode current of the device is found to increase from a very low value in substantially linear manner up to a maximum value. Further increase of the potential difference will not produce any increase in the anode current. If the anode is arranged to emit substantially no secondary electrons it is found that the slope of the linear portion of the anode current curve is relatively steep.
  • the varying voltage may be a high frequency alternating voltage, in which case the anode current of the multiplier will contain an alternating current component of the same frequency, the amplitude of which will depend upon the slope of the anode current curve, 1. e., upon the primary emission. If the primary emission is changed in accordance with the amplitude of signals to be amplified by the multiplier it is clear that the slope will vary in a corresponding manner, and hence the alternating anode current will be modulated in amplitude in accordance with the signals. This obviously enables a carrier frequency to be introduced and of great value when the amplification of weak signals is to be accomplished since a low loss circuit may now be utilised as the output circuit of the multiplier. Furthermore, if suitable steps are taken to neutralise the capacity between the anode and the preceding secondary electron emitting electrode, it is possible to arrange that the output current falls to zero when the primary electron emission is zero, so that modulation can be effected.
  • the varying voltage in this case is preferably applied between the anode and the immediately preceding secondary electron emitting electrode, and in a preferred embodiment of the invention it is applied in such a way that the potential of the latter is kept constant whilst the potential of the former is varied about a mean potential which gives the necessary mean potenial difierence be tween the two electrodes.
  • the electron multiplier has a photo cathode, and a varying light beam produces a primary emission which varies in accordance with the brightness of the picture points of the picture to be transmitted.
  • the necessary carrier current is then introduced in the manner described above.
  • the varying voltage may also be representative of the signals to be amplified by the multiplier, in which case the primary emission is kept constant. This enables one to use a thermionic cathode as the source of the primary emission.
  • Fig. 1 shows the curves obtained by plotting the anode current against the potential difierence between the anode and the preceding electrode
  • Fig. 2 shows a circuit diagram of a preferred form of the invention. 7
  • an electron multiplier l comprises a photo electric cathode 2, a plurality of secondary electron emitting grids 36, and an anode 7.
  • the grids 3-6 are held at progressively increasing potentials with respect to the cathode 2, these potentials being derived from the potential divider 8.
  • a small potential difierence equal to the mean potential difference V1 of Fig. 1 exists between the terminals 9 so that the anode l is slightly more positive than the grid 6 by this amount.
  • a light beam of varying intensity falls upon the cathode 2 thus setting up a primary electron emission of varying intensity.
  • a locally generated carrier frequency is applied to the terminals l of the circuit H and is injected across the electrodes 6, 1 via the lower half of the centre tapped inductance l2 of the circuit [3.
  • a neuage between successive grids 3, 4, 5, 6 is -120 volts, the potential V1 between the terminals 9 should be in the neighbourhood of 6 volts.
  • An electrical circuit arrangement including an electron multiplier having a plurality of sec ondary electron emitting electrodes in the form GEORGE WILLIAM WALTON.

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  • X-Ray Techniques (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US244061A 1937-12-10 1938-12-05 Electron multiplier circuits Expired - Lifetime US2245119A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB34300/37A GB514297A (en) 1937-12-10 1937-12-10 Improvements in or relating to electron multipliers and circuits therefor

Publications (1)

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US2245119A true US2245119A (en) 1941-06-10

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US244061A Expired - Lifetime US2245119A (en) 1937-12-10 1938-12-05 Electron multiplier circuits

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US (1) US2245119A (enrdf_load_stackoverflow)
FR (1) FR847309A (enrdf_load_stackoverflow)
GB (1) GB514297A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2420753A (en) * 1943-11-10 1947-05-20 Hazeltine Research Inc Wave-signal translating system
US2617948A (en) * 1948-11-18 1952-11-11 Heinz E Kallmann Electron multiplying device
US2777948A (en) * 1951-06-14 1957-01-15 Farnsworth Res Corp Blanking circuit for electron multiplier
US2828424A (en) * 1954-04-15 1958-03-25 Time Inc Photoelectric method and apparatus

Families Citing this family (2)

* 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
DE975101C (de) * 1955-03-31 1961-08-10 Telefunken Patent Speicheranordnung mit einer elektronischen Speicherroehre

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2420753A (en) * 1943-11-10 1947-05-20 Hazeltine Research Inc Wave-signal translating system
US2617948A (en) * 1948-11-18 1952-11-11 Heinz E Kallmann Electron multiplying device
US2777948A (en) * 1951-06-14 1957-01-15 Farnsworth Res Corp Blanking circuit for electron multiplier
US2828424A (en) * 1954-04-15 1958-03-25 Time Inc Photoelectric method and apparatus

Also Published As

Publication number Publication date
FR847309A (enrdf_load_stackoverflow) 1939-10-06
GB514297A (en) 1939-11-06

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