US2147669A - Secondary electron emitting electrode - Google Patents

Secondary electron emitting electrode Download PDF

Info

Publication number
US2147669A
US2147669A US123203A US12320337A US2147669A US 2147669 A US2147669 A US 2147669A US 123203 A US123203 A US 123203A US 12320337 A US12320337 A US 12320337A US 2147669 A US2147669 A US 2147669A
Authority
US
United States
Prior art keywords
electrode
borate
layer
metal
electron
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
US123203A
Other languages
English (en)
Inventor
Emanuel R Piore
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.)
RCA Corp
Original Assignee
RCA Corp
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
Priority to NL51148D priority Critical patent/NL51148C/xx
Priority to BE426040D priority patent/BE426040A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US123203A priority patent/US2147669A/en
Priority to GB578/38A priority patent/GB491287A/en
Priority to CH204059D priority patent/CH204059A/de
Priority to DER101443D priority patent/DE750047C/de
Application granted granted Critical
Publication of US2147669A publication Critical patent/US2147669A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/32—Secondary-electron-emitting electrodes

Definitions

  • My invention relates to electric discharge devices, particularly to secondary-electron emitting electrodes for use therein, and has for its principal object the provision of improvements in electrodes of the general type disclosed in a copcnding application Serial No. 77,092 to Vladimir K. 'Zworykin and Louis Malter, filed April 30, 1986, and assigned to Radio Corporation of America.
  • caesiated silver was generally considered to be the best surface material for secondary-emissive electrodes. Electrodes constructed in accordance with the prior art, of silver, oxidized and then sensitized by the formation thereon of a layer of caesium oxide, appear to be capable of emitting no more than substantially nine or ten secondary electrons to each impinging primary electron. As a consequence, wherever copious secondary emission is desired, the prior art dictates the use of a number of secondary emitting electrodes in cascade. Such an arrangement is quite well exemplified by French Patent No. 582,428, which discloses an electron multiplier comprising three secondary electron emitting electrodes.
  • Zworykin and Malter achieve an output with a single multiplying electrode equivalent to that heretofore achieved only in tubes employing many electron multiplying stages.
  • Electrodes which is constituted of a layer of an oxide of an alkali metal, a conductive base, and an interposed insulating layer of substantially microscopic thinness.
  • the present invention is predicated upon my discovery that an electrode treated with certain materials other than those described in the Zworykin and Malter disclosure may exhibit the above-described. anomalous emission efiect.
  • an electrode comprising a conductive base covered with an insulating layer of an alkaline earth metal derivative and a superimposed layer of an alkali metal, such, for example, as rubidium, caesium, or the oxides thereof, is capable of emitting a copious flow of secondary electrons.
  • the intermediate, insulating layer may be constituted of a borate of any one, or mixture of two or more, alkaline earth metals and, as above indicated, the outer surface layer, which receives the positive charge, may be constituted of caesium or its oxide.
  • the base upon which the insulating layer is imposed may be formed of almost any conducting material, such, for example, as nickel, aluminum, silver, or alloys thereof.
  • Figure l is a diagrammatic view of an electron multiplier system wherein an electrode constructed according to my invention may advantageously be utilized, and
  • Figure 2 is a diagrammatic, enlarged, sectional View of a multiplying electrode constructed in accordance with the principle of my invention.
  • an electron multiplier in which an electrode formed according to my invention can be utilized may comprise a Y-shape evacuated container 1 within which, adjacent to the extreme end of one of the arms, is mounted a photosensitive cathode 3 and within the end of the other arm of which is mounted an output electrode 5.
  • the cathode material may be silver, having a surface layer comprising caesium oxide.
  • the photosensitive cathode which is the source of primary electrons ' may be replaced by any other source of electrons such as a thermionic cathode or another secondary emitting electrode.
  • An electrode 1 capable of emitting secondary electrons is disposed within the stem of the container in such position that it is accessible to electrons emitted from the photosensitive cathode 3 and is also visible from the output electrode 5.
  • the electrode l mounted in the stem of the container will be referred to as a multiplying electrode.
  • a variab-leor a constant light source may be s0. disposed with respect to the container that light therefrom falls upon the photosensitive cathode.
  • such light source is exemplified by a light 8 connected in circuit with a battery 9 and a variable rheostat I l, and a lens Under the influence of light from the source, electrons leave the surface of the photosensitive cathode in random directions.
  • an electromagnetic coil I may be disposed around one arm of the container between the photosensitive cathode and the multiplying electrode.
  • a similar coil l'l may be disposed around the other arm of the container for the purpose of focusing secondary electrons upon the output electrode.
  • the several focusing coils may be provided with uni-directional potential from a battery l9 or the like.
  • these coils are exemplified as being connected in parallel to the battery, a potential divider 2
  • the polarity of the coils is immaterial.
  • electrostatic focusing of the electrons may be resorted to, or a combination of electrostatic and magnetic focusing.
  • the output electrode 5 may be connected to any suitable utilization circuit, such as a relay 27.
  • the photosensitive cathode may be connected to the negative terminal of a potential divider 29 that is connected across a source of uni-directional potential 3
  • the relative potentials shown in the drawing are to be construed solely as illustrative.
  • the multiplying electrode 1 may have a base portion 33 made of a sheet of nickel, aluminum, silver, copper or any other metal which is readily degassed, or it may be formed of glass or the like plated with metal to give it a conductive surface.
  • This surface 33 carries an insulating layer or film 35 constituted essentially of a borate of an alkaline-earth-metal, such, for example, as barium borate, strontium borate, calcium borate, or mixtures of the same.
  • superimposed on the borate film is a very thin layer 31 of an emissive material selected from the group comprising the alkali-metals and the oxides thereof. Each layer is of a thickness preferably no greater than .001 of an inch.
  • the alkaline-earth-metal-borate layer 35 may be applied to the conductive surface 33 prior to being mounted within the tube I. This may be accomplished by mounting the surface 33 in an evacuated vessel containing a filament of spiral or cylindrical contour supporting, as between the turns, a small quantity of fused borate and then evaporating the borate as by heating the filament.
  • One advantage of coating the metal in a separate tube is that several electrodes, or a large surface which may be later cut up to electrode size, may be treated at one time. If it is desired to coat the surface 33 with the electrodes all mounted in place in the device of Fig. 1 the tube may be provided with a neck portion (not shown), near the electrode 1, in which the auxiliary heater supporting the borate'is mounted.
  • the neck will ordinarily be sealed off after the borate coating is applied.
  • the tube is highly exhausted and. a slight amount of alkali-metal, such as sodium, potassium, rubidium or caesium is distilled in to it. Caesium is preferred. sufficient alkali metal is used to form a thin coating upon the borate layer on electrode 1 and to sensitize the cathode 3.
  • the caesium coating should preferably be no thicker than substantially .001" and may be comprised of no more than a molecularly thin coating.
  • the coating on electrode 1, in this case, is probalby discontinuous and it may be that it consists of spaced apart molecules of the metal, insulated by the borate from each other and from the underlying conductive base 33.
  • the caesium interpenetrates the borate layer to some extent.
  • layer, film, surface coating and the like, here used are not to be construed as necessarily implying physical continuity and homogeneity, but are to be given as broad an interpretation as is consistent with my disclosure.
  • the tube after the introduction of the alkali metal, is preferably baked at 200 C. for approximately ten minutes and then permitted to cool to room temperature. Subsequent to cooling, pure oxygen is admitted into the tube to react with the caesium and is permitted to remain therein for a short time. The tube is then re-evacuated to a pressure sufficiently low to prevent ionization during use. Presumably, the alkali metal which deposits on the alkaline-earth-metal-borate layer 35 is oxidized and the ability of the electrode 1 to emit true secondary electrons is thereby enhanced.
  • Method of preparing an electrode having a metal surface which comprises depositing a thin layer .of a borate of an alkaline-earth metal upon said surface and subsequently depositing a thin layer of an electron-emissive material upon said alkaline-earth-metal borate layer.
  • Method of preparing an electrode having a metal surface which comprises depositing a thin layer of a borate of an alkaline-earth metal upon said surface, subsequently depositing a thin layer of an alkali metal upon said alkaline-earthmetal-borate layer and thereafter oxidizing the said alkali metal layer.
  • An electron emissive electrode comprising a conductive base, an electron-emissive surface layer and an intermediate layer constituted essentially of a borate of an alkaline-earth metal.
  • An electron-emissive electrode comprising a conductive base, an electron-emissive surface layer formed of a material selected from the group comprising the alkali-metals, and an intermediate layer constituted essentially of a borate of an alkaline-earth metal.
  • An electron-emissive electrode comprising a conductive base, an electron-emissive surface layer constituted of an oxide of an alkali metal, and an intermediate layer constituted essentially of a borate of an alkaline-earth metal.

Landscapes

  • Discharge Lamp (AREA)
  • Gas-Filled Discharge Tubes (AREA)
  • Solid Thermionic Cathode (AREA)
US123203A 1937-01-30 1937-01-30 Secondary electron emitting electrode Expired - Lifetime US2147669A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL51148D NL51148C (en:Method) 1937-01-30
BE426040D BE426040A (en:Method) 1937-01-30
US123203A US2147669A (en) 1937-01-30 1937-01-30 Secondary electron emitting electrode
GB578/38A GB491287A (en) 1937-01-30 1938-01-07 Improvements in secondary electron emitting electrodes suitable for electron discharge devices
CH204059D CH204059A (de) 1937-01-30 1938-01-28 Elektrische Entladungsröhre.
DER101443D DE750047C (de) 1937-01-30 1938-02-01 Sekundaeremissionsfaehige Elektrode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US123203A US2147669A (en) 1937-01-30 1937-01-30 Secondary electron emitting electrode

Publications (1)

Publication Number Publication Date
US2147669A true US2147669A (en) 1939-02-21

Family

ID=22407273

Family Applications (1)

Application Number Title Priority Date Filing Date
US123203A Expired - Lifetime US2147669A (en) 1937-01-30 1937-01-30 Secondary electron emitting electrode

Country Status (6)

Country Link
US (1) US2147669A (en:Method)
BE (1) BE426040A (en:Method)
CH (1) CH204059A (en:Method)
DE (1) DE750047C (en:Method)
GB (1) GB491287A (en:Method)
NL (1) NL51148C (en:Method)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2428289A (en) * 1942-11-07 1947-09-30 Charles Schiffman Electron tube coating
US2443324A (en) * 1942-11-07 1948-06-15 Charles Schiffman Electronic tube
US2527981A (en) * 1945-08-23 1950-10-31 Bramley Jenny Secondary-electron emission
US2639963A (en) * 1948-04-05 1953-05-26 Sylvania Electric Prod Secondary emitter and method of manufacture
US2846338A (en) * 1954-08-03 1958-08-05 William G Shepherd Secondary electron emitter
US4047999A (en) * 1974-09-19 1977-09-13 Francis John Salgo Method of making a mobile ion film memory

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2530946A (en) * 1949-04-02 1950-11-21 Bell Telephone Labor Inc Secondary electron emitter

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE356578A (en:Method) * 1927-12-14
US2141322A (en) * 1935-06-25 1938-12-27 Rca Corp Cascaded secondary electron emitter amplifier

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2428289A (en) * 1942-11-07 1947-09-30 Charles Schiffman Electron tube coating
US2443324A (en) * 1942-11-07 1948-06-15 Charles Schiffman Electronic tube
US2527981A (en) * 1945-08-23 1950-10-31 Bramley Jenny Secondary-electron emission
US2639963A (en) * 1948-04-05 1953-05-26 Sylvania Electric Prod Secondary emitter and method of manufacture
US2846338A (en) * 1954-08-03 1958-08-05 William G Shepherd Secondary electron emitter
US4047999A (en) * 1974-09-19 1977-09-13 Francis John Salgo Method of making a mobile ion film memory

Also Published As

Publication number Publication date
NL51148C (en:Method)
CH204059A (de) 1939-04-15
BE426040A (en:Method)
GB491287A (en) 1938-08-30
DE750047C (de) 1944-12-11

Similar Documents

Publication Publication Date Title
US2842706A (en) Cold cathode vacuum tube
US3021472A (en) Low temperature thermionic energy converter
US2643297A (en) Gas discharge transmission arrangement
US2527981A (en) Secondary-electron emission
US3114044A (en) Electron multiplier isolating electrode structure
US2147669A (en) Secondary electron emitting electrode
GB305574A (en:Method)
US2620287A (en) Secondary-electron-emitting surface
US2123024A (en) Electrode for electric discharge devices
US2263032A (en) Cold cathode electron discharge tube
US2178238A (en) Electric discharge device
US3240970A (en) Method and apparatus for replenishing hydrogen in a neutron generator
US2700626A (en) Secondary electron emissive electrodes
US2316276A (en) Electron discharge apparatus
US2468417A (en) Cascade amplifying circuit using gaseous discharge tubes
US2205055A (en) Electric discharge device
US2034571A (en) Electrical discharge device and method of operating same
US2171224A (en) Cathode ray tube
US1723869A (en) Electrical discharge device
US2833953A (en) High voltage electron tube
US3382397A (en) Ion source having a high work function material coating the outer surface of the ionizer
US2677070A (en) Coated grid tube
US2184910A (en) Cold cathode electron discharge tube
US2037075A (en) Phototube
US3569755A (en) Vacuum tube and method of making it