US2285848A - Electron multiplier - Google Patents

Electron multiplier Download PDF

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Publication number
US2285848A
US2285848A US326813A US32681340A US2285848A US 2285848 A US2285848 A US 2285848A US 326813 A US326813 A US 326813A US 32681340 A US32681340 A US 32681340A US 2285848 A US2285848 A US 2285848A
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United States
Prior art keywords
cathode
electrons
cathodes
auxiliary electrode
secondary cathode
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Expired - Lifetime
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US326813A
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English (en)
Inventor
Francois Joseph Gerard V Bosch
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.)
VACUUM SCIENCE PRODUCTS Ltd
VACUUM-SCIENCE PRODUCTS Ltd
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VACUUM SCIENCE PRODUCTS Ltd
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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
    • H01J43/06—Electrode arrangements
    • H01J43/18—Electrode arrangements using essentially more than one dynode
    • H01J43/22—Dynodes consisting of electron-permeable material, e.g. foil, grid, tube, venetian blind

Definitions

  • This invention relates to electron multipliers consisting of electron discharge devices in which one or more electrodes are employed for producing secondary electron emission in order to obtain the electron multiplication.
  • electron multipliers comprise a primary cathode, one or more secondary cathodes and a collector enclosed in an envelope and so arranged that the electrons emitted by the primary cathode are caused to impinge on a secondary cathode and liberate other electrons which impinge on the next secondary cathode, when more than one, and so on in succession to the collector.
  • an electron multiplier comprising, for a secondary cathode, an auxiliary apertured electrode spaced from the secondary cathode in the direction of approach of electrons to this secondary cathode.
  • an electron multiplier comprising a secondary cathode having apertures for the passage of electrons liberated by the secondary cathode to a succeeding electrode and an auxiliary apertured electrode spaced from the secondary cathode in the direction of approach of electrons to this secondary cathode.
  • the auxiliary electrode is operated at a potential which is the same, or substantially the same, as the operating potential applied to the associated secondary cathode. In this manner, there is produced in front of the secondary cathode a uniform field which very materially increases the multiplication factor obtained by the secondary cathode.
  • the auxiliary electrode is preferably uniformly spaced from the secondary cathode and it is convenient for the secondary cathode and the auxiliary electrode to be mounted one upon the other so as to be in direct electrical connection, and therefore operate at the same standing potential.
  • this secondary cathode may be in the form of a wire grid or mesh or a perforated plate or of any other construction providing a surface on which approaching electrons may impinge, and an opening or openings through which the secondary electrons may pass to a succeeding electrode.
  • the auxiliary electrode preferably consists of a wire grid r mesh or perforated plate with one or more apertures, constructed and arranged to offer little restriction to the passage of electrons to the secondary cathode.
  • the secondary cathode consists of a perforated plate
  • the auxiliary electrode consists of another perforated plate arranged with the perforations out of line with those of the secondary cathode so that electrons passing the auxiliary electrode are caused to impinge on the secondary cathode.
  • this plate is preferably arranged with the perforations of the plate in line with those of the succeeding auxiliary electrode so that the auxiliary electrode does not materially impede the passage of electrons.
  • a further feature of the invention consists in the provision of a control grid between the secondary cathode and the auxiliary electrode associated therewith.
  • a control grid used in this position has the advantage that the electron emission at the secondary cathode is not affected by the control electrode.
  • Figure 1 is a circuit diagram of a multiplier according to the invention
  • Figure 2 is a perspective View of the multiplier employed in Figure 1
  • Figure 3 is a diagram showing the provision of a control grid for a secondary cathode.
  • Figure 1 is a detail View of one form of secondary cathode and auxiliary electrode.
  • the electron multiplier comprises an envelope 10 containing a'thermiom'c cathode H and its heater l2. Associated with this cathode there is an input control grid 13 and an accelerator 14. The primary electrons from the cathode l I are directed towards the first one of a succession of secondary cathodes l5 which are in the form of perforated metal plates. There is a final secondary cathode Iii in the form of a disc and an output or collector electrode I! in the formof a grid interposed between the secondary cathode l6 andthe last of the secondary cathodes] 5.
  • each of the secondary cathodes I 5 consists of a perforated metal plate, in which the perforations indicated at I8 are of diminishing cross-section and in which there is a peripheral flange l9 for electrostatically'focusing the electrons as they leave the secondary cathode,"as' described'in the specification of UnitedStatespatent application No. 276,883, filed June 1, 1939.
  • auxiliary electrode which, in the construction shown in Figure 2, consists of a grid formed of very fine wire.
  • auxiliary electrodes 20 is directly mounted in front of the associated secondary cathode so as to be in direct electrical connection with the cathode, but uniformly spaced in front of it.
  • has its secondary winding connected to the control grid [3 and cathode I l of the multiplier.
  • a potential divider consisting of resistances 22, a further resistance 23 and a resistance 24 having a variable tapping is for connection at 25 and 26 respectively to the positive and negative poles of a high tension supply.
  • the secondary cathodes l5 are connected respectively to the higher potential terminals of the resistances 22 and the accelerator I4 is connected to the higher potential terminal of the resistance 23 so that there is applied to these electrodes progressively increasing potentials with respect to the cathode which is connected to a tapping on the resistance 24.
  • the negative terminal of this resistance is connected to the secondary winding of the transformer 2
  • An additional high tension supply is applied with its positive and negative poles at 2! and 25 respectively across a potential divider consisting of resistances 28 and 29.
  • the junction of these resistances is connected to the secondary cathode l6 and the high potential end of the resistance 28 is connected through the primary winding of an output transformer 30 to the collector H.
  • the electron emission from the last of these secondary cathodes passes through the collector grid [1 to the final secondary cathode [6, the secondary emission from which is collected at the grid IT.
  • the provision of the auxiliary electrode serves to screen the secondary electrons from the preceding emitting electrode, which has an operating potential negative to that of the secondary cathode from which the electrons came, and enables a considerable increase in multiplication to be obtained.
  • these secondary electrons will be mainly or entirely at the front of the electrode emitting them and will have different velocities.
  • the auxiliary electrode serves to screen the space between this electrode and the associated secondary cathode, into which space the secondary electrons are emitted, from the infiuence of the preceding secondary cathode and permits the more active penetration of the accelerating field of the succeeding secondary cathode into this space.
  • control grid 3! which may conveniently be of wire grid or mesh form.
  • may have a modulating or control potential applied to it.
  • it may be connected to a circuit tuned to required signal frequencies and furthermore it may be biassed or constructed for rectification of modulated carrier wave signals applied to the control grid I3 for amplification by the multiplier.
  • These control grids 3! do not affect the secondary emission of the secondary cathodes with which they are associated because oi the provision of the auxiliary electrode 20.
  • a perforated plate may be employed similar to that forming the secondary cathode.
  • Such an arrangement is shown diagrammatically in Figure 4 in which the perforated plate forming the auxiliary electrode 20 has its perforations 32 staggered with respect to the perforations l8 of the secondary cathode with which it is associated, but in line with the perforations I8 of the preceding secondary cathode beneath it in Figure 4.
  • the auxiliary electrode offers a minimum of obstruction to electrons approaching the associated secondary cathode and tends to direct such electrons so that they impinge on the secondary cathode.
  • the secondary cathodes are spaced 6 to 8 mm. apart and the auxiliary electrode is positioned 3 or 4 mm. in front of the secondary cathode with which it is associated, that is to say, midway between successive secondary cathodes.
  • the invention is applicable also to electron multipliers having one or more secondary cathodes in which apertures are not provided and in which the secondary electrons are drawn away sideways from the surface of the cathode'instead of through the cathode.
  • the invention is thus applicable to electron multipliers of the Zworykin type in which there is employed a plurality of secondary cathodes spaced apart in a single plane with deflectors for causing the electrons to follow a curved path between each of these secondary cathodes, and to electron multipliers of the Slepian type in which the secondary cathodes are arranged in two groups spaced apart, a cathode of one group being positioned opposite the space between adjacent cathodes of the other group, so that the electrons follow a zig-zag path between the cathodes of the two groups alternately.
  • An electron multiplier comprising a primary cathode, a plurality of secondary cathodes each consisting of a perforated plate and a collector electrode, an auxiliary electrode positioned between successive secondary cathodes and also consisting of a perforated plate, the perforations in said auxiliary electrode'being in line with the 1 perforations of the preceding secondary cathode and staggered in relation to the perforations in the succeeding secondar cathode.
  • An electron multiplier comprising a primary cathode, a plurality of secondary cathodes each consisting of a perforated plate and a collector electrode, an auxiliary electrode positioned between successive secondary cathodes and also consisting of a perforated plate, the perforations in said auxiliary electrode being in line with the perforations of the preceding secondary cathode and staggered in relation to the perforations in the succeeding secondary cathode, and a control electrode interpositioned between the secondary cathode and the auxiliary electrode.

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Electron Sources, Ion Sources (AREA)
  • Electron Tubes For Measurement (AREA)
  • X-Ray Techniques (AREA)
US326813A 1939-05-11 1940-03-29 Electron multiplier Expired - Lifetime US2285848A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB14124/39A GB531541A (en) 1939-05-11 1939-05-11 Improvements in electron multipliers

Publications (1)

Publication Number Publication Date
US2285848A true US2285848A (en) 1942-06-09

Family

ID=10035425

Family Applications (1)

Application Number Title Priority Date Filing Date
US326813A Expired - Lifetime US2285848A (en) 1939-05-11 1940-03-29 Electron multiplier

Country Status (5)

Country Link
US (1) US2285848A (en, 2012)
BE (1) BE438865A (en, 2012)
FR (1) FR872190A (en, 2012)
GB (1) GB531541A (en, 2012)
NL (1) NL59599C (en, 2012)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2602921A (en) * 1946-10-12 1952-07-08 Sperry Corp Aircraft traffic control system
US5689152A (en) * 1995-04-26 1997-11-18 U.S. Philips Corporation Electron multiplier for a multi-channel photomultiplier tube

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2602921A (en) * 1946-10-12 1952-07-08 Sperry Corp Aircraft traffic control system
US5689152A (en) * 1995-04-26 1997-11-18 U.S. Philips Corporation Electron multiplier for a multi-channel photomultiplier tube

Also Published As

Publication number Publication date
NL59599C (en, 2012)
FR872190A (fr) 1942-06-01
GB531541A (en) 1941-01-07
BE438865A (en, 2012)

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