US2159774A - Secondary electron emitter and method of making it - Google Patents

Secondary electron emitter and method of making it Download PDF

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Publication number
US2159774A
US2159774A US195942A US19594238A US2159774A US 2159774 A US2159774 A US 2159774A US 195942 A US195942 A US 195942A US 19594238 A US19594238 A US 19594238A US 2159774 A US2159774 A US 2159774A
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US
United States
Prior art keywords
metal
secondary electron
electrode
oxide
magnesium
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
US195942A
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English (en)
Inventor
Veenemans Cornelis Frederik
Lopp Edmund Heinrich
Bruining Hajo
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
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
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Application filed by Philips Gloeilampenfabrieken NV filed Critical Philips Gloeilampenfabrieken NV
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Publication of US2159774A publication Critical patent/US2159774A/en
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Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/12—Manufacture of electrodes or electrode systems of photo-emissive cathodes; of secondary-emission electrodes
    • H01J9/125—Manufacture of electrodes or electrode systems of photo-emissive cathodes; of secondary-emission electrodes of secondary emission electrodes
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/32—Secondary emission electrodes

Definitions

  • This invention relates to an electric discharge tube comprising a secondary electron emitting .electrode or emitter with at least a part of its surface consisting of a substance readily emittin secondary electrons when struck by a stream of primary electrons t
  • a secondary electron emitting .electrode or emitter with at least a part of its surface consisting of a substance readily emittin secondary electrons when struck by a stream of primary electrons t
  • Various materials have been used for secondary electron emission electrodes, such as the alkali metals and their oxides, for example, caesium, l and the alkaline earth metals such as barium and strontium and their oxides, and in addition magnesium and aluminum and their oxides have been suggested.
  • these electrodes or emit-- ters can be made by methods of manufacture v known for primary thermionic cathodesffor instance, by applying the material containing the active metal to the secondary electron emission electrode by vaporization from a primary cathode.
  • excellent secondary electron emittters may be made in accordance with our invention.
  • an electric discharge tube comprising a secondary GQ litfsifil ⁇ electrode or emitter the active substance fionsisting of a compound of a metal 'selected
  • the gas pressure must have a value such that ⁇ 35 the compound, and not merely a metal surface is produced.
  • a reacting or inert gas atmosphere may be used.
  • the pressure 4c of the gas need not be as high as for the vaporization of the metals themselves.
  • the method maybe carried out in diflerent ways.
  • a source of alkali metal, alkaline earth metal, or magnesium either the metal or a readily decomposable compound of the l 55. metal
  • a gas such as carbon dioxide, oxygen, and the like, for example, has been introduced at a suitable pressure into the tube.
  • a gas such as carbon dioxide, oxygen, and the like, for example
  • a carbon dioxide atmosphere is obtained by providing barium-strontium car- 10 bonate on a separate heatable electrode, and ma nesium at another point of the tube, and by heating the carbonate shortly before vaporization of the magnesium to such a degree that carbon dioxide is set free and part, of the re- 1 suiting barium and strontium oxide also evaporates to the secondary electron emitter, so that the secondary electron emission electrode is finally coated with a mixture of barium oxide, strontium oxide, and magnesium oxide having a very good secondary electron emission and a ratio of secondary to primary electrons much greater than unity at practicable voltages.
  • the invention will be more clearly understood by reference to the accompanying drawing representing, by wayof example, a discharge tube in which the method of the invention may be used.
  • This tube comprises .a cathode 2, coated with barium and strontium oxides, a control grid 3, and a screen grid 4.
  • the electrons issuing from the cathodeare led along curved paths, schematically represented by the arrows 5, to a secondary emission electrode 6 and an anode I.
  • the secondary electron emitting electrode 6 is preferably a sheet of nickel having on its active surface a thin layer or film of barium oxide, strontium oxide, and magnesium oxide applied in accordance with our invention.
  • the tube comprises a curved accelerating electrode 8 and a shield 9 which serve to direct the electron discharge along curved paths and at the same time prevent material evaporating from the primary cathode from reaching the secondary emission electrode.
  • the accelerating electrode 8 is sprayed with a thin layer Ill of barium-strontium I 2 e I T 2,159 ⁇ ?” magnesium I l on the shield 9 is evaporated in the atmosphere of carbon dioxide and forms magnesium oxide on the electrode 6, In this case care has to be taken that the carbon dioxide is at 'such a pressure that no surface of metallic magnesium is formed.
  • the easily detectable pressure developed in the tube by the decomposition of the carbonates is suilicient. As a result,
  • the surface of the nickel electrode is coated .
  • a layer ofactive material in the form of an intimateadmixture consisting predominantly of oxides from the barium strontium carbonate coating, and of the oxide or compound of the "vaporized metal, such as magnesium.
  • metallic magnesium is not observable on the coating, although it is possible that minute amounts of metal are present in it;
  • the method of forming in a tube a metal electrode having a surface of high secondary electron emissivity which comprises evacuating the tube, heating an alkaline earth metal carbonate in the tube to a temperature at which the carbonate decomposes with'evolutlonvof carbon di- 7 oxide gas and some alkaline earth metal oxide, and
  • a secondary electron emitter comprising a sheet of nickel having a surface coated with a mixture consisting predominantly of an alkaline 5 earth metal oxide and of magnesium oxide.
  • a secondary electron emitter comprising sheet of nickel having a surface coated with a mixture consisting predominantly of an alkaline earth metal oxide and not an oxide of a dlficrent o metal selected irom the group comprising the alkali metals, the alkaline earth metals, and
  • a secondary electron emitting electrode which comprises enclosing a 5 metal electrode in an evacuated vessel, produc ing in'said vessel an atmosphere of carbon dioxide, depositing on said metal electrode in said atmosphere a thin him of alkaline earth metal oxide, and vaporizing in said atmosphere a difmnict metal selected from the group of alkali metals, alkaline earth metals, and magnesium to form a layer of oxide of said different metal on said fllm of alkaline earth metal oxides.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Discharge Lamp (AREA)
  • Gas-Filled Discharge Tubes (AREA)
  • Solid Thermionic Cathode (AREA)
US195942A 1937-03-30 1938-03-15 Secondary electron emitter and method of making it Expired - Lifetime US2159774A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL207921X 1937-03-30

Publications (1)

Publication Number Publication Date
US2159774A true US2159774A (en) 1939-05-23

Family

ID=19778652

Family Applications (1)

Application Number Title Priority Date Filing Date
US195942A Expired - Lifetime US2159774A (en) 1937-03-30 1938-03-15 Secondary electron emitter and method of making it

Country Status (7)

Country Link
US (1) US2159774A (en(2012))
BE (1) BE427228A (en(2012))
CH (1) CH207921A (en(2012))
DE (1) DE747205C (en(2012))
FR (1) FR835838A (en(2012))
GB (1) GB498792A (en(2012))
NL (1) NL50262C (en(2012))

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2422088A (en) * 1944-04-03 1947-06-10 Rca Corp Electronic discriminator
US2553997A (en) * 1948-01-24 1951-05-22 Emi Ltd Thermionic valve utilizing secondary electron emission amplification
US2556166A (en) * 1939-02-27 1951-06-12 Int Standard Electric Corp Electron switch, structures, and circuits
US2581460A (en) * 1939-02-03 1952-01-08 Int Standard Electric Corp Electron multiplier
US2602905A (en) * 1945-10-24 1952-07-08 Emi Ltd Electron discharge device
US2792273A (en) * 1954-01-14 1957-05-14 Gen Electric Oxide coated nickel cathode and method of activation
US2878093A (en) * 1955-02-14 1959-03-17 Univ Minnesota Method of preparing emitter surfaces

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE914418C (de) * 1939-02-19 1954-07-01 Fernseh Gmbh Entladungsroehre mit einer sekundaeremittierenden Isolieroberflaeche
DE895629C (de) * 1940-07-31 1953-11-05 Zeiss Ikon Ag Verfahren zur Herstellung von Sekundaeremissionskathoden

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT101557B (de) * 1923-04-11 1925-11-10 Philips Nv Entladungsröhre.
BE359997A (en(2012)) * 1928-05-14
GB443214A (en) * 1934-08-20 1936-02-20 Albert Karl Franz Patin Improved method of applying coatings of alkali or alkaline earth metals

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2581460A (en) * 1939-02-03 1952-01-08 Int Standard Electric Corp Electron multiplier
US2556166A (en) * 1939-02-27 1951-06-12 Int Standard Electric Corp Electron switch, structures, and circuits
US2422088A (en) * 1944-04-03 1947-06-10 Rca Corp Electronic discriminator
US2602905A (en) * 1945-10-24 1952-07-08 Emi Ltd Electron discharge device
US2553997A (en) * 1948-01-24 1951-05-22 Emi Ltd Thermionic valve utilizing secondary electron emission amplification
US2792273A (en) * 1954-01-14 1957-05-14 Gen Electric Oxide coated nickel cathode and method of activation
US2878093A (en) * 1955-02-14 1959-03-17 Univ Minnesota Method of preparing emitter surfaces

Also Published As

Publication number Publication date
GB498792A (en) 1939-01-13
FR835838A (fr) 1939-01-04
CH207921A (de) 1939-12-15
BE427228A (en(2012))
DE747205C (de) 1944-09-15
NL50262C (en(2012))

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