US2146099A - 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
US2146099A
US2146099A US143946A US14394637A US2146099A US 2146099 A US2146099 A US 2146099A US 143946 A US143946 A US 143946A US 14394637 A US14394637 A US 14394637A US 2146099 A US2146099 A US 2146099A
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US
United States
Prior art keywords
carbon
layer
heating
secondary electron
electrode
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
US143946A
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English (en)
Inventor
Boer Jan Hendrik De
Bruining Hajo
Prakke Frits
Karel Marinus Van Gessel
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
Publication date
Application filed by Philips Gloeilampenfabrieken NV filed Critical Philips Gloeilampenfabrieken NV
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    • 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 a surface havini a high secondary electron emitting capacity and to a method of manufacturing such a surface.
  • a surface according to the invention consists of a pure carbon layer having a high adsorption power and having adsorbed to it one or more metals of the second,
  • a surface according to the present invention may be established, for instance, by coating a supporting body or electrode for example, of nickel with a carbon layer and by applying on ,to said layer one or more of the metals referred to. Particularly good results are achieved when heating a metal surface in an atmosphere of a simple hydrocarbon, preferably acetylene, in a high frequency member.
  • a simple hydrocarbon preferably acetylene
  • a pure carbon layer is formed on the metal surface, which layer eminently adsorbs alkaline earth metals.
  • one or more of the abovementioned metals are then caused to be adsorbed from the vapour-phase by such a layer.
  • a supporting body such as a nickel electrode is coated with a layer consisting of one or more oxides or hydroxides of these metals, preferably with magnesium oxide, whereon carbon is precipitated by high frequency heating in an atmosphere consisting of a simple hydrocarbon, the body thus obtained being subsequently heated for some time in a. high vacuum.
  • the hydrocarbons may, for instance, be acetylene, methane or the like.
  • the heating operation after provision of the carbon may, for 5 instance, be effected at a temperature of 900 to 1000 C. Very probably the oxide is partly reduced thereby and the metal produced is adsorbed to the carbon.
  • l surfaces according to the present invention may advantageously be used in electric discharge tubes, more particularly in socalled electron multipliers.
  • the method according to the invention may be carried out as follows. l
  • a nickel electrode is coated with a layer of magnesium oxide, which may be effected, for instance, by spraying.
  • An electrode thus coated is introduced into an acetylene atmosphere and then the electrode is covered with a carbon layer by high frequency heating. This treatment may, for instance, take several minutes. After that the electrode together with other parts is introduced into the bulb of a discharge tube and then the tube is exhusted. After that the surface obtained is heated, for some moments to a temperature of about 900 C. which may also be effected by high frequency heating. It has been found that a surface thus established permits a secondary emission to be obtained of the order of magnitude of 6 secondary electrons per primary electron at a voltage of 500 volts.
  • Figure 1 shows the steps of the method according to the invention
  • Figure 2 shows in greatly enlarged cross-section a portion of an electrode made in accordance with the invention.
  • the outer rectangles numbered I, 2, 3, and 4 represent the successive steps of the method, rectangles 2 and 4 representing steps 4 which are always used.
  • the small rectangles inside rectangles l and 3 represent alternative ways of carrying out the first and third steps. If, in step I the alternative a is adopted, and the core is clean or uncoated nickel, then in step 3 the alternative a of exposure to magnesium vapor is followed. If, in step I the alternative I: is adopted, and the core is nickel with a magnesia coating, then in step 3 the alternative b of proceeding directly to the final step is followed. 55
  • pure carbon layer contains or is impregnated with an alkaline earth metal such as magnesium absorbed in the carbon layer as indicated by the small crosses I, and supplied to the carbon layer by exposure to vaporized magnesum, or by reductlon of the magnesia on the magnesia coated core by the carbon.
  • an alkaline earth metal such as magnesium absorbed in the carbon layer as indicated by the small crosses I
  • the method of making a surface having secondary electron emissivity several times unity which consists in coating a metal core body with a, coating of carbon by heating said body by high frequency induction heating in an atmosphere of a simple hydrocarbon, metallizing the surface of said coated body by depositing on it an alkaline earth metal from the vapor-phase, and then heating the metallized body in vacuum.
  • the method of making a surface having secondary electron emissivity several times unity which consists in coating a metal core body with a layer of carbon absorbent of alkaline earth metal by heating said body by high frequency induction to a high temperature in an atmosphere of acetylene at substantially room temperature, exposing said carbon coated body in vacuum to an excess of vapor of an alkaline earth metal to cause metal from the vapor-phase to be adsorbed by said carbon coated body, and then heating said body by high frequency induction heating to about 900 C.
  • the method of producing an electrode havin secondary electron emissivity several times unity which comprises coating a body of nickel with carbon highly absorbent of alkaline earth metal by heating said body to a high temperature in an atmosphere of acetylene by high frequency induction heating, treating said carbon coated body at room temperature with an excess of magnesium vapor to impregnate said carbon with magnesium, and heating said body in vacuum at about 900 C. for several minutes to activate said electrode.
  • a secondary electron emitting electrode having a ratio of secondary electron emission of several times unity upon impact by primary electrons at several hundred volts which comprises a metal core, a layer of alkaline earth oxide on and adherent to said core, and a pure carbon coating on and in contact with said layer and having the alkaline earth metal of said layer absorbed in said carbon.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Discharge Lamp (AREA)
  • Cold Cathode And The Manufacture (AREA)
US143946A 1936-02-10 1937-05-21 Secondary electron emitter and method of making it Expired - Lifetime US2146099A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE473398X 1936-02-10

Publications (1)

Publication Number Publication Date
US2146099A true US2146099A (en) 1939-02-07

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ID=6541560

Family Applications (1)

Application Number Title Priority Date Filing Date
US143946A Expired - Lifetime US2146099A (en) 1936-02-10 1937-05-21 Secondary electron emitter and method of making it

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US (1) US2146099A (enrdf_load_html_response)
BE (1) BE419911A (enrdf_load_html_response)
FR (1) FR817503A (enrdf_load_html_response)
GB (1) GB473398A (enrdf_load_html_response)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2472189A (en) * 1941-07-03 1949-06-07 Hartford Nat Bank & Trust Co Thermionic tube having a secondary-emission electrode
US2820728A (en) * 1955-06-21 1958-01-21 Diamond Alkali Co Method of treating carbon electrodes with polymerizable oil

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2530167A (en) * 1944-12-14 1950-11-14 Hartford Nat Bank & Trust Co Discharge tube

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2472189A (en) * 1941-07-03 1949-06-07 Hartford Nat Bank & Trust Co Thermionic tube having a secondary-emission electrode
US2820728A (en) * 1955-06-21 1958-01-21 Diamond Alkali Co Method of treating carbon electrodes with polymerizable oil

Also Published As

Publication number Publication date
GB473398A (en) 1937-10-12
BE419911A (enrdf_load_html_response)
FR817503A (fr) 1937-09-04

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