US2639996A - Filamentary cathode - Google Patents

Filamentary cathode Download PDF

Info

Publication number
US2639996A
US2639996A US81854A US8185449A US2639996A US 2639996 A US2639996 A US 2639996A US 81854 A US81854 A US 81854A US 8185449 A US8185449 A US 8185449A US 2639996 A US2639996 A US 2639996A
Authority
US
United States
Prior art keywords
nickel
oxide
aluminum
filamentary
coating
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
US81854A
Other languages
English (en)
Inventor
Jacobs Harold
Hees George
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.)
GTE Sylvania Inc
Original Assignee
Sylvania Electric Products Inc
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 NL78158D priority Critical patent/NL78158C/xx
Application filed by Sylvania Electric Products Inc filed Critical Sylvania Electric Products Inc
Priority to US81854A priority patent/US2639996A/en
Priority to GB6554/50A priority patent/GB673237A/en
Application granted granted Critical
Publication of US2639996A publication Critical patent/US2639996A/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
    • H01J1/13—Solid thermionic cathodes
    • H01J1/14—Solid thermionic cathodes characterised by the material
    • H01J1/146—Solid thermionic cathodes characterised by the material with metals or alloys as an emissive material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/294—Coated or with bond, impregnation or core including metal or compound thereof [excluding glass, ceramic and asbestos]
    • Y10T428/2958—Metal or metal compound in coating

Definitions

  • cathodes of the prior art had a tendency to break or cause short circuits due to their poor strength qualities while operating in a heated condition.
  • the object of this invention is to provide a method of increasing the rate of activation of oxide coated cathodes.
  • a still further defect of this invention is to provide a method of manufacuning oxide coated eathode'skhaving a'filamentary core of cobalt aluminum or nickel aluminum which can be activatedmore readily than heretofore deemed possible.
  • a still further :obj'ect of this invention is to provide an oxide coated cathode having a nickel or cobalt aluminum filamentary "core which can be readily activated.
  • Fig. 1 illustrates a .plan view of aspecial emission diode which is adaptable to the study of thermionic electron emission.
  • Fig. 2 is a trout elevation of the tube shown in Fig.1.
  • the special electron tube shown in the drawings contains three nickel cylinders 10, 12 and :4 which are used as anodes in a standard soft glass lock in" ty e vacuum tube :bulb I6.
  • lament 2D is vertically 'suppor ted'within the tube iii by means of supports 22 and 24.
  • the end cylinders Ill and M are provided with slots [8 which help these cylinders act as guard'rings and help provide a uniform electrost'atic field at that portion of the filament as it is being studied.
  • the use of guard rings also minimizes the end effect, that-is, the cooling of the ends or the filament by thermal conduction.
  • the center anode i2 is isolated electrically and used as the collector for the emission studies.
  • the tube is further equipped with a getter which may be barium aluminum so shielded that it only flashes on the tube walls to abscrbany .gas which may be liberated during life. To reduce the probability of marked evolution of gas no mica or lava spaces are used in the illustrated tube but all spacing is accomplished by means of nickel supports.
  • the filament -20 is preferablymade of a nickel aluminum alley or of a-cobalt aluminum alloy. Both of these alloys have been found suitable for "the production of cathodes capable of copious thermionic emission and both can withstand high temperatures In the case of the nickel alloy the preferred percentage has been found to 'be approximately '2 atomic percent of aluminum. In the case of the cobalt alloy. the atomic percentage is approximately one percent. A greater percentage of aluminum results in greater emission. In the manufacture of these filaments, it has been found that it is of definite advantage to vacuum melt these alloys before drawing them into wire. This undoubtedly improves the purity of the product. At any rate it certainly has been found to improve its emission characteristics.
  • the filament 20 is coated with an oxide coatmg capable of giving thermionic emission.
  • an oxide coatmg capable of giving thermionic emission.
  • a triple carbonate mixture containmg a small amount of nickel oxide has been found to be preferable if the best results are to be obtained.
  • the triple carbonate coating is well known and widely used in the art.
  • the addition of the nickel oxide is novel. When this latter ingredient is added, it promotes the activation of the thermionic emitter and materially cuts down the time necessary to reach peak emission.
  • This filament coating can naturally be applied in many ways including spraying and electrophoresis.
  • nickel oxide and the standard triple carbonate suspen sion containing approximately 38.6 mol percent of barium carbonate, 15.2 mol percent calcium carbonate and 46.2 mol percent of strontium carbonate suspended in lacquer is cataphoretically applied to the filament to an approximate oxide diameter of 0.0065 inch,
  • the coating density is preferably held within 1.0 plus or minus 0.3 gram per centimeters squared.
  • the amount of nickel oxide used is preferably kept at about 5% by weight of solid material although there is nothing critical in the percentage of this material used. It is preferably added to the triple carbonate in the form of a powder before it is applied to the filament to form the cathode coating.
  • the addition of the nickel oxide increases the rate of activation of both the nickel aluminum triple carbonate coated filament and the cobalt aluminum triple carbonate coated filaments
  • the rate of activation is more marked in the case of the cobalt aluminum alloy base than it is in the case where the nickel aluminum alloy is used as the filamentary material.
  • the triple carbonate coated cobalt aluminum alloy without the addition of the nickel oxide to the oxide coating takes much longer to activate than does the nickel aluminum based filament. It is therefore readily apparent that in view of the fact that the cobalt aluminum alloys are the slowest to activate, the nickel oxide is especially useful in the coating of these materials since they present the greatest problem from the point of view of activation time.
  • the nickelous oxide when added to the triple carbonate to form the coating does show an appreciable decrease in activating time for the coated filament, the nickelous oxide does not seem to have any additional efiect that is to say, when once the filament material has reached its highest level of thermionic emission, it is substantially the same as that for filaments coated with triple carbonate but Without the addition of the nickelous oxide, On the other hand, in this connection, it should also be noted that the nickelous oxide has no harmful effect when once the filament has been properly activated.
  • a filamentary cathode capable of giving copious thermionic emission comprising a core of an alloy selected from the group consisting of nickel aluminum containing approximately 2% aluminum and cobalt aluminum containing approximately 1 aluminum with an electron emissive oxide coating containing 2 to 5% nickel oxide.
  • a filamentary cathode capable of giving copious thermionic emission comprising a core 01' a nickel aluminum alloy with an electron emissive oxide coating containing 2 to 5% of nickel oxide, said alloy containing substantially 2% of aluminum.
  • a filamentary cathode capable of giving copious thermionic emission comprising a core of a cobalt aluminum alloy with an electron emissive oxide coating containing 2 to 5% of nickel oxide, said alloy containing approximately 1% of aluminum.
  • a filamentary cathode capable of giving a copious thermionic emission comprising a core of a nickel aluminum alloy with an electron emissive oxide coating containing approximately 5% of nickel oxide said alloy containing substantially 2% of aluminum.
  • a filamentary cathode capable of giving copious thermionic emission comprising a core of a cobalt aluminum alloy with an oxide coating containing a mixture of barium, strontium and calcium oxides together with 2-5% of nickel oxide said alloy containing approximately 1% of aluminum.

Landscapes

  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Solid Thermionic Cathode (AREA)
US81854A 1949-03-17 1949-03-17 Filamentary cathode Expired - Lifetime US2639996A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL78158D NL78158C (en, 2012) 1949-03-17
US81854A US2639996A (en) 1949-03-17 1949-03-17 Filamentary cathode
GB6554/50A GB673237A (en) 1949-03-17 1950-03-15 Improvements in and relating to oxide-coated cathodes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US81854A US2639996A (en) 1949-03-17 1949-03-17 Filamentary cathode

Publications (1)

Publication Number Publication Date
US2639996A true US2639996A (en) 1953-05-26

Family

ID=22166827

Family Applications (1)

Application Number Title Priority Date Filing Date
US81854A Expired - Lifetime US2639996A (en) 1949-03-17 1949-03-17 Filamentary cathode

Country Status (3)

Country Link
US (1) US2639996A (en, 2012)
GB (1) GB673237A (en, 2012)
NL (1) NL78158C (en, 2012)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111446140A (zh) * 2020-04-27 2020-07-24 中国科学院国家空间科学中心 一种用于空间探测仪器的阴极及其制备方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1925978A (en) * 1931-02-04 1933-09-05 Kemet Lab Co Inc Alloy and article composed of same
US2003609A (en) * 1932-08-26 1935-06-04 Electrons Inc Preparation of composite substances
US2041802A (en) * 1933-06-30 1936-05-26 Bell Telephone Labor Inc Electron emitter
US2049372A (en) * 1934-11-19 1936-07-28 Gen Electric Emissive coating for cathodes and method for preparing the same
US2081864A (en) * 1934-11-24 1937-05-25 Electrons Inc Of Delaware Emissive cathode
US2085605A (en) * 1934-05-11 1937-06-29 Gen Electric Thermionic cathode for electric discharge devices
US2103267A (en) * 1926-11-20 1937-12-28 Rca Corp Alloy for vacuum tube elements
US2185410A (en) * 1938-09-30 1940-01-02 Rca Corp Metal compositions

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2103267A (en) * 1926-11-20 1937-12-28 Rca Corp Alloy for vacuum tube elements
US1925978A (en) * 1931-02-04 1933-09-05 Kemet Lab Co Inc Alloy and article composed of same
US2003609A (en) * 1932-08-26 1935-06-04 Electrons Inc Preparation of composite substances
US2041802A (en) * 1933-06-30 1936-05-26 Bell Telephone Labor Inc Electron emitter
US2085605A (en) * 1934-05-11 1937-06-29 Gen Electric Thermionic cathode for electric discharge devices
US2049372A (en) * 1934-11-19 1936-07-28 Gen Electric Emissive coating for cathodes and method for preparing the same
US2081864A (en) * 1934-11-24 1937-05-25 Electrons Inc Of Delaware Emissive cathode
US2185410A (en) * 1938-09-30 1940-01-02 Rca Corp Metal compositions

Also Published As

Publication number Publication date
NL78158C (en, 2012)
GB673237A (en) 1952-06-04

Similar Documents

Publication Publication Date Title
GB1005386A (en) Improvements in discharge lamps with cathode shields
US2624024A (en) Cathode for use in electron discharge tubes
US2806970A (en) Electron emission coatings and method of preparing air stabilized barium oxide
US2419902A (en) Fluorescent electric discharge lamp
US3563797A (en) Method of making air stable cathode for discharge device
US2769112A (en) Discharge lamp, mount therefor, and method
US2639996A (en) Filamentary cathode
US2497111A (en) Electron tube having carburized thoriated cathode
US2085605A (en) Thermionic cathode for electric discharge devices
JPH04259725A (ja) 酸化物陰極
GB485476A (en) Improvements in and relating to electric incandescent lamps
US2686274A (en) Thermionic cathode
US2153009A (en) Electric discharge lamp
US2175696A (en) Electron emitter
Benjamin I. The influence of impurities in the core-metal on the thermionic emission from oxide-coated nickel: Part I. of a thesis approved for the degree of doctor of philosophy in the University of London
US2840751A (en) Electrode coating composition and electrode for cold cathode gas discharge lamp
US2657325A (en) Electrode for electric discharge lamps
US3069580A (en) Fluorescent lamp
US2959702A (en) Lamp and mount
US2740914A (en) Thermionic cathodes
US2885587A (en) Low pressure discharge lamp and method
US2208692A (en) Active metal compound for vacuum tubes
US2831137A (en) Cathode coating
US3597271A (en) Method of producing air stable alkaline-earth metal oxide while avoiding eutectic melting
US3070550A (en) Cathodes for electron tubes