US2200722A - Electron discharge device - Google Patents

Electron discharge device Download PDF

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Publication number
US2200722A
US2200722A US205929A US20592938A US2200722A US 2200722 A US2200722 A US 2200722A US 205929 A US205929 A US 205929A US 20592938 A US20592938 A US 20592938A US 2200722 A US2200722 A US 2200722A
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United States
Prior art keywords
cathode
collector electrode
electron
cathodes
electrode
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Expired - Lifetime
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US205929A
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English (en)
Inventor
John R Pierce
Gordon K Teal
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AT&T Corp
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Bell Telephone Laboratories Inc
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Publication date
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US205929A priority Critical patent/US2200722A/en
Priority to US205930A priority patent/US2274092A/en
Priority to US227649A priority patent/US2207355A/en
Priority to FR853617D priority patent/FR853617A/fr
Application granted granted Critical
Publication of US2200722A publication Critical patent/US2200722A/en
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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
    • H01J43/20—Dynodes consisting of sheet material, e.g. plane, bent

Definitions

  • This invention relates to electron discharge devices and more particularly to such devices, such as shown in the applications Serial No. 205,930,
  • Electron multipliers of a type comprehended by this invention comprise a source of primary electrons, such, for example, as a photoelectric cathode, an anode or collector electrode spaced from the primary electron source, and one or a plurality of secondary electron emissive cathodes between the primary electron source and the anode or collector electrode.
  • a source of primary electrons such, for example, as a photoelectric cathode, an anode or collector electrode spaced from the primary electron source, and one or a plurality of secondary electron emissive cathodes between the primary electron source and the anode or collector electrode.
  • the operating characteristics of such an electron multiplier are. dependent to a large extent upon the direction and intensity of the various fields extant between the various electrodes which fields determine, among other things, the electron trajectories and the character and magnitude of the emission from the various secondary cathodes.
  • the various fields are determined primarily by the form of the various electrodes and, more particularly, by the shape of l the emissive surfaces of the various cathodes and by the relative disposition of the electrodes.
  • One general object of this invention is to obtain such fields and distribution thereof in an electron multiplier that eiilcient and stable operation obtains and uniform characteristics throughout a wide range of interelectrode potentials and input frequencies are achieved.
  • objects of this invention are:
  • the primary andvsecondary cathodes'in an electron multiplier are so shaped and spacially related that strong fields away from the emissive surfaces thereof obtain and the electrons emanating from each cathode are converged and focussed upon a restricted portion of the next succeeding electrode.
  • means are provided in cooperative relation with the anode or collector electrode for producing a saddle back in the field adjacent the face of the anode or collector electrode directed emission from the antoward the last secondary cathode, and a retard-' ing field around the anode or collector electrode.
  • Fig. 1 is a perspective view of an electron multiplier illustrative of one embodiment of this invention, portions of the enclosing vessel and of the electrode structure being broken away to show details more clearly;
  • Fig. 2 is a side view, mainly in section, of the electrode assembly incorporated in the electron multiplier shown in Fig. 1;
  • Fig. 3 is a top view along line 3-3 of Fig. 1;
  • Fig. 4 is an enlarged diagrammatic dimensioned side view of one of the secondary cathodes in the electron multiplier shown in Fig. 1;
  • Fig. 5 is a diagrammatic detail side view of the collector electrode or anode end of the electrode assembly illustrated in Fig. 2 and incorporated in the multiplier shown in Fig. 1; and I Fig. 6 is a circuit diagram illustrating one manner in which an electron multiplier constructed in accordance with this invention may be operated.
  • the electron multiplier there shown comprises a highly evacuated enclosing vessel It having at one end thereof an inwardly extending, generally cylindrical stem ll. Clamped about the stem II are a pair of semicircular bands or collars l2 from which the electrodes, fabricated in a unitary assembly, are supported.
  • This assembly comprises an insulating spacer member l3, for example, a mica disc, which is mounted upon a plurality (four) of rigid bands or collars i2 and aflixed to these uprights, as by eyelets l5.
  • a primary cathode l8 mounted between and supported by the insulating uprights iii
  • a primary cathode l8 is mounted between and supported by the insulating uprights iii
  • a primary cathode l8 is mounted between and supported by the insulating uprights iii
  • anode or collector electrode l9 mounted between and supported by the insulating uprights iii are a primary cathode l8, an anode or collector electrode l9 and a plurality of secondary cathodes 20 to 20 ,.inclusive, the "cathodes being mounted in two parallel rows and in staggered relation.
  • the primary and secondary cathodes are identical in form and dimensions except that the first secondary cathode 20 is slightly shorter than the other cathodes, the decrease in length being due
  • the various secondary cathodes 20 to 20 are so mounted and arranged that they have glide plane symmetry; that is, they are so arranged and mounted that if one row of secondary cathodes were displaced longitudinally a distance a, as indicated in Fig. 2, parallel to the medial plane (see A-A, Fig. 2) between the two :rows of cathodes, each cathode in one row would be exactly opposite a corresponding cathode in the other row.
  • these cathodes are so mounted and arranged that they are symmetrical with respect to a longitudinal plane normal to the medial plane mentioned above.
  • the electrodes do not have symmetry with respect to any plane, such as one passing through the line 3-3 in Fig. 2, normal to both the medial plane and the longitudinal plane previously mentioned.
  • Each of the primary and secondary cathodes l8 and 20, respectively, may be formed of a strip of metal, for example, silver, and has a continuously curved portion, the concave surface of which is treated or coated so that the concave surface of the primary cathode i8 is photoelectrically active and the concave surface of each of the secondary cathodes 20 is secondary electron emissive.
  • the concave surface of each of the primary and secondary cathodes may be treated to form thereon a coating or matrix including silver, caesium oxide and some free caesium.
  • the cathodes i8 and 20 preferably have side flanges 22 which assist in preventing lateral dispersion'of the electrons emanating from the emissive surfaces thereof.
  • support members or brackets which may be, for example, of
  • the anode or collector electrode may be a relatively small area metallic plate disposed obliqueuprights or. posts I extending from the 1y to the medial plane between the rows of secondary cathodes 20- and supported by a pair of bent wires 21 extending through and fitted in suitable apertures in the insulating uprights l6. Leading-in connection to the anode or collector electrode may be made through a conductor 50.
  • the cathodes may be maintained at successively equally higher potentials. That is to say, for example, the first secondary cathode 20 may be maintained of the order of twenty-five to one hundred volts positive with respect to the primary cathode IS, the next secondary cathode 20 may be maintained of the order of twenty-five to one hundred volts positive with respect to the secondary cathode 20 and each succeeding secondary cathode may be maintained similarly positive with respect to the next preceding secondary cathode.
  • the potentials for thevarious cathodes may be obtained from a potentiometer arrangement including a resistance 28 having equally spaced taps to which the cathodes are connected, the resistance 28 being shunted by a suitable source such as rectifier 29.
  • the anode or collector electrode I9 may be maintained of the order of twenty-five to one hundred volts positive with respect to the last secondary cathode 20 as by a source such as a battery 30.
  • each impinging primary electron will cause the release of a plurality of secondary electrons so that the secondary electron current emitted from the cathode 20 will be greater, for example, four to eight times, than the primary electron current thereto. Consequently, in effect, an electron multiplication and a corresponding amplification of the signal corresponding to the light beam played upon the primary cathode will result.
  • the secondary electrons emanating from the cathode 26 under the influence of the fields between this cathode and the secondary cathode 20 will be drawn toward and impinge upon the latter cathode and cause the release of a still greater number of secondary electrons therefrom.
  • This phenomenon is repeated at each of the secondary cathodes 20 so that the secondary electron current emanating from the secondary cathode Ml will represent a very large amplification of the signal corresponding to the light beam focussed upon the primary cathode l8.
  • the secondary electrons emanating from the cathode 20 are attracted toward and impinge upon the anode or collector electrode I9 and constitute the output current of the electron multiplier.
  • the fields adjacent the concave surface of each of the cathodes be such that the emanating electrons are accelerated away from these surfaces and, in addition, that the fields be such that the electrons emanating from each concave surface are concentrated and fairly sharply focussed upon a concave surface of the next succeeding electrode.
  • the fields between the various successive electrodes are primarily dependent upon the shape of the electrode surfaces. The proper direction of these fields resulting in copious emission and concentration or focussing of the electrons may be obtained in accordance with this invention by shaping the secondary cathodes so that the concave surfaces are of the form and have the relative dimensions indicated in Fig. 4.
  • the relative dimensions are expressed in units, a typical unit being, for example, one-thousandth of an inch.
  • the fields adjacent the emitting surfaces of the various cathodes are dependent also upon the relative spacings of these electrodes.
  • the critical spacings are indicated in Fig. 5 wherein a equals 250 units and b equals 418 units, a typical unit being one-thousandth of an inch, as above.
  • auxiliary or field electrodes 32 to 32, inclusive mounted between the two rows of secondary cathodes 20.
  • these auxiliary electrodes may be linear small area rods or wires extending between the insulating uprights l6 and ,fitted in apertures therein. As shown clearly in Fig.
  • the auxiliary electrode 32 may be mounted opposite the concave surface of the primary cathode l8 and immediately adjacent and parallel to the upper edge of the first secondary cathode 20
  • Each of the auxiliary electrodes 32 to 32 inclusive, may be mounted opposite the secondary cathode having the same superscript and immediately adjacent and parallel to the upper edge of the secondary cathode having the next higher superscript.
  • the auxiliary electrode 32 may be mounted opposite the concave surface of the last secondary cathode 20
  • the auxiliary electrodes 32 to 32 are equally spaced and are mounted parallel to one another and in the medial plane extending between the two rows of cathodes.
  • auxiliary electrodes 32 Individual connection may be established to the auxiliary electrodes 32 by leading-in conductors 33 extending through suitable apertures in the spacer disc l3 and sealed in the wall of the enclosing vessel III, as indicated at 25.
  • each of the auxiliary electrodes 32 may be maintained at a higher positive potential than the corresponding opposite cathode and the next succeediug cathode.
  • each auxiliary electrode may be maintained at the same potential as the one having the second greater superscript. That is to say, for example, the auxiliary electrode 32 may be maintained at the same potential as the secondary cathode 20', the auxiliary electrode 32 may be maintained at the same potential as the secondary cathode 20 and so on.
  • Each of the auxiliary electrodes 32 thus operated will produce a strong field component away from the opposite emissive surface. ,That is, for example, the auxiliary electrode 32 will produce a strong field component away from the concave surface of the primary cathode l3 and each of the auxiliary electrodes 32 to 32 will produce a strong field component away from the concave thereto.
  • auxiliary electrodes 32 assist in producing convergence of the electron streams and the focussing thereof upon restricted portions of the next succeeding electrodes.
  • auxiliary electrodes 32 cause a turning or bending of the electron streams.
  • This turning or bending effect is dependent upon the potential of the several auxiliary electrodes 32 and control of the electron streams, therefore, may be effected by varying the potentials of these electrodes. For example, these potentials may be made such that the electrons arrive at each secondary cathode with a substantially grazing incidence, which condition is most favorable to the production of copious secondary emission.
  • the gain of the multi plier may be varied and its output may be modulated through the controlling of the bending or turning of the electron streams. That is to say, for example, the potentials may be such that the electrons emanating from one or more of the secondary cathodes do not impinge upon the emissive surface of ,thenext succeeding cathode, or impinge upon a portion thereof which does not contribute substantially to electron multiplication.
  • d 1 equals 231 units, a typical unit being as given heretofore.
  • the collector electrode or anode I 9 may be substantially enclosed on three sides by an auxiliary or screen electrode 34 which, asshown clearly in Fig. 2, has three walls at right angles to each other and is supported by and between the insulating uprights l6 by a plurality of wires 35 fitted in apertures in the uprights l6.
  • auxiliary or screen electrode 34 which, asshown clearly in Fig. 2, has three walls at right angles to each other and is supported by and between the insulating uprights l6 by a plurality of wires 35 fitted in apertures in the uprights l6.
  • this auxiliary or screen electrode is electrically integral with the secondary electrode 20". It may be formed integral with this cathode or fabricated separately and joined to this cathode.
  • baille or field plate 36 Mounted in cooperative relation with the secondary' cathodes 20" and 20 and the anode or collector electrode I9 is a baille or field plate 36 which is supported by bent wires 31 fitted in apertures in the insulating upright 16 and extends obliquely toward the medial plane between the rows of secondary cathodes; Leading-in connection to the baflie or field plate 36 may be established through a conductor 38.
  • a second baflle or field plate 39 having a leading-in conductor 5
  • the baflle or field plate 39 is slightly offset with respect to the medial plane passing between the rows of secondary cathodes and is parallel
  • the bafile or field plate 36 may be maintained at the same potential as the auxiliary electrode 32" and the baflie or field electrode, 39 may be operated at the same potential as the auxiliary electrode 32
  • the secondary electrons emanating from the last secondary cathode 20 are subjected to strong fields accelerating them toward the medial or symmetry plane and they finally arrive at the anode or collector electrode !9, the fields being produced by the baffle or field electrodes 36 and 39 and by the auxiliary electrode 32
  • these secondary electrodes In passing from the symmetry plane to the anode or collector electrode, these secondary electrodes cross a saddle back in the potential field due to the potentials of the secondary cathode 2B", the field electrodes 36 and 39, and the screen or shield electrode 34. They are accelerated toward the anode or collector'electrode and focused upon it.
  • the screen electrode 34 and the baflie or field electrode 36 or 33 produce a saddle back in the potential field in front of the anode or collector electrode I9, that is, the face thereof toward the secondary electrode 20, and produce also a retarding field around the anode or collector electrode i9.
  • secondary electrons are prevented from passing from the anode or collector electrode to the baffle or plate electrodes 36 and 39 and the use of an additional or higher collector electrode potential is rendered unnecessary.
  • this arrangement of the electrodes assures that the electron current arriving at the anode or collector electrode I9 is substantially unaffected by potential changes arising from or attributable to changes in the current of the output circuit. It may be noted, also, that the electrons emanating from the last secondary cathode 2B are concentrated and sharply focused so that a small area collector electrode or anode may be utilized and, hence, a low capacity output achieved.
  • An electron multiplier comprising a pair of electron emissive members and an anode mounted successively in staggered relation,- and a shield memberenclosing saidanode' on three sides and having an open side toward the emissive member opposite said anode, said shield member being electrically integral with the other electron emissive member.
  • An electron multiplier comprising a primary cathode, a collector electrode, a secondary cathode between said primary cathode and said collector electrode and having an electron emissive surface facing said collector electrode, and a pair of field electrodes between said surface and said collector electrode and mounted obliquely. to said collector electrode.
  • An electron multiplier comprising a primary cathode, a collector electrode, a secondary cathode between said primary cathode and said collector electrode and having an electron emissive surface toward said collector electrode, and a pair of auxiliary electrodes opposite spaced portions of said surface for focussing electrons emanating therefrom upon said collector electrode said auxiliary electrodes being mounted at different angles'with respect to said collector electrode.
  • An electron multiplier in accordance with claim 3 comprising means having portions opposite the surface of said collector electrode remote from said first surfacefor preventing diffusion of electrons about said collector electrode.
  • An electron multiplier comprising a primary cathode, a collector electrode, a secondary cathode between said primary cathode and said collector electrode and having an emissive surface facing said collector electrode, and means for shaping the field between said surface and said collector electrode including electrodes between said surface and said collector electrode and an electrode partially encompassing said collector electrode.
  • An electron multiplier comprising a primary cathode, a collector electrode, a secondary cathode having a dished emissive surface facing said collector electrode, a second secondary cathode having a dished emissive surface facing said first surface, a field electrode between said first surface and said collector electrode, and a second field electrode between said dished surfaces, said field electrodes being disposed on opposite sides of a medial plane passing between said dished surfaces.

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US205929A 1938-05-04 1938-05-04 Electron discharge device Expired - Lifetime US2200722A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US205929A US2200722A (en) 1938-05-04 1938-05-04 Electron discharge device
US205930A US2274092A (en) 1938-05-04 1938-05-04 Electron discharge device
US227649A US2207355A (en) 1938-05-04 1938-08-31 Electron discharge device
FR853617D FR853617A (fr) 1938-05-04 1939-04-28 Dispositifs à décharge électronique par émissions secondaires successives

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US205929A US2200722A (en) 1938-05-04 1938-05-04 Electron discharge device

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US2200722A true US2200722A (en) 1940-05-14

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2416303A (en) * 1941-02-05 1947-02-25 Bell Telephone Labor Inc Secondary emissive shell resonator tube
US2485586A (en) * 1947-02-01 1949-10-25 Int Standard Electric Corp Geiger counter
US2868994A (en) * 1955-10-24 1959-01-13 Rca Corp Electron multiplier
US2903595A (en) * 1954-12-24 1959-09-08 Rca Corp Electron multiplier
US3258402A (en) * 1960-02-26 1966-06-28 Itt Electric discharge device for producing interactions between nuclei
US4415832A (en) * 1981-11-20 1983-11-15 Rca Corporation Electron multiplier having an improved planar utlimate dynode and planar anode structure for a photomultiplier tube
US4426596A (en) 1981-02-24 1984-01-17 Rca Corporation Photomultiplier tube having a heat shield with alkali vapor source attached thereto
US4446401A (en) * 1981-11-20 1984-05-01 Rca Corporation Photomultiplier tube having improved count-rate stability
US4570102A (en) * 1984-05-18 1986-02-11 Rca Corporation Photomultiplier tube having an electron multiplier cage assembly with uniform transverse spacing

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2416303A (en) * 1941-02-05 1947-02-25 Bell Telephone Labor Inc Secondary emissive shell resonator tube
US2485586A (en) * 1947-02-01 1949-10-25 Int Standard Electric Corp Geiger counter
US2903595A (en) * 1954-12-24 1959-09-08 Rca Corp Electron multiplier
US2868994A (en) * 1955-10-24 1959-01-13 Rca Corp Electron multiplier
US3258402A (en) * 1960-02-26 1966-06-28 Itt Electric discharge device for producing interactions between nuclei
US4426596A (en) 1981-02-24 1984-01-17 Rca Corporation Photomultiplier tube having a heat shield with alkali vapor source attached thereto
US4415832A (en) * 1981-11-20 1983-11-15 Rca Corporation Electron multiplier having an improved planar utlimate dynode and planar anode structure for a photomultiplier tube
US4446401A (en) * 1981-11-20 1984-05-01 Rca Corporation Photomultiplier tube having improved count-rate stability
US4570102A (en) * 1984-05-18 1986-02-11 Rca Corporation Photomultiplier tube having an electron multiplier cage assembly with uniform transverse spacing

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Publication number Publication date
FR853617A (fr) 1940-03-23

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