US3490944A - Cathode heater for electron discharge device - Google Patents

Cathode heater for electron discharge device Download PDF

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Publication number
US3490944A
US3490944A US578143A US3490944DA US3490944A US 3490944 A US3490944 A US 3490944A US 578143 A US578143 A US 578143A US 3490944D A US3490944D A US 3490944DA US 3490944 A US3490944 A US 3490944A
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US
United States
Prior art keywords
layer
cathode
dark
electron discharge
discharge device
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
US578143A
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English (en)
Inventor
Friedrich Hermann Raymun Almer
Adrianus Kuiper
Cornelis Maan
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.)
US Philips Corp
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US Philips 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
Application filed by US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3490944A publication Critical patent/US3490944A/en
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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
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/22—Heaters

Definitions

  • the invention relates to a heater body for use in an indirectly heated cathode, this body being coated with a layer preferably consisting of pure alumina and with a dark-colored layer consisting of a mixture of metal oxide particles and metal particles of darker color, and more particularly to a heater body in which the dark-colored particles consist of tungsten.
  • a heating wire can be coated with an insulating layer consisting of pure alumina to which a second layer is applied which consists of alumina mixed with approximately 50% by weight of tungsten powder.
  • a second layer which consists of alumina mixed with approximately 50% by weight of tungsten powder.
  • the dark-colored layer has a considerably lower insulation resistance than the subjacent A1 0 layer. This may result in the occurrence of leakage current between the cathode and the heater body or of breakdown if the A1 0 substratum exhibits pores or cracks. The substratum must therefore be sintered very carefully, which is expensive. Moreover, the dark-colored layer must terminate at a certain distance from the end of the subjacent A1 0 layer in order not to get into contact with the heating wire.
  • the metal oxide particles of the dark-colored layer consist of one or more of the following oxides: magnesia, beryllium oxide, thorium oxide, zirconium oxide. Thorium oxide and zirconium oxide have proved to be particularly suitable and it has been found that with the use of these Oxides the percentage of rejects is low.
  • the insulation resistance between the cathode and the heating wire is also found to be particularly high during the cathode lifetime.
  • the high resistance may be due to the possibility that these oxides react with the A1 0 of the substratum and form a junction layer so that the p-n junctions may be obtained which consequently have a blocking effect on leakage currents.
  • the mean size both of the oxide particles and of the metal particles of the dark-colored layer is approximately the same and is preferably approximately ln while the largest particles are preferably not larger than 12,. This can be obtained by sieving the powder ground for a long time in a sieve having 360 meshes/cm. As described in copending application Ser. No. 575,570, filed Aug. 29, 1966, now abandoned. It has been found that the insulation resistance may be further increased by the application to the dark-colored layer of a third layer consisting or one or more of the oxides of Mg, Be, Zr, or Th. If this layer has a thickness of only a few microns, the heat radiation of the dark-colored layer is substantially not influenced, since such a thin layer is pervious to the heat radiation.
  • the drawing illustrates the coated article of the invention.
  • a heater body for use in an indirectly heated cathode said body being coated with a layer consisting of pure alumina and with a dark-colored layer consisting of a mixture of metal oxide particles and metal particles of darker color, said metal oxide particles consist of an oxide selected from the group consisting of magnesia, beryllium oxide, thorium oxide and zirconium oxide.

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  • Solid Thermionic Cathode (AREA)
  • Heat Sensitive Colour Forming Recording (AREA)
  • Casting Devices For Molds (AREA)
US578143A 1965-09-23 1966-09-09 Cathode heater for electron discharge device Expired - Lifetime US3490944A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6512348A NL6512348A (fi) 1965-09-23 1965-09-23

Publications (1)

Publication Number Publication Date
US3490944A true US3490944A (en) 1970-01-20

Family

ID=19794213

Family Applications (1)

Application Number Title Priority Date Filing Date
US578143A Expired - Lifetime US3490944A (en) 1965-09-23 1966-09-09 Cathode heater for electron discharge device

Country Status (12)

Country Link
US (1) US3490944A (fi)
AT (1) AT263156B (fi)
BE (1) BE687198A (fi)
CH (1) CH477085A (fi)
DE (1) DE1564448C3 (fi)
DK (1) DK118198B (fi)
ES (1) ES331443A1 (fi)
FI (1) FI43089B (fi)
FR (1) FR1501048A (fi)
GB (1) GB1121035A (fi)
NL (1) NL6512348A (fi)
NO (1) NO119366B (fi)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5293410A (en) * 1991-11-27 1994-03-08 Schlumberger Technology Corporation Neutron generator
US20090108192A1 (en) * 2007-10-25 2009-04-30 Schulumberger Technology Corporation Tritium-Tritium Neutron Generator Logging Tool

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3581144A (en) * 1969-03-27 1971-05-25 Gen Electric Metal-clad insulated electrical heater

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3195004A (en) * 1960-08-19 1965-07-13 Rca Corp Cathode heater for electron discharge devices
US3328201A (en) * 1964-04-27 1967-06-27 Rca Corp Heater for electron tubes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3195004A (en) * 1960-08-19 1965-07-13 Rca Corp Cathode heater for electron discharge devices
US3328201A (en) * 1964-04-27 1967-06-27 Rca Corp Heater for electron tubes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5293410A (en) * 1991-11-27 1994-03-08 Schlumberger Technology Corporation Neutron generator
US20090108192A1 (en) * 2007-10-25 2009-04-30 Schulumberger Technology Corporation Tritium-Tritium Neutron Generator Logging Tool

Also Published As

Publication number Publication date
FR1501048A (fr) 1967-11-10
CH477085A (de) 1969-08-15
DE1564448A1 (de) 1970-03-05
AT263156B (de) 1968-07-10
DE1564448B2 (de) 1975-05-15
DE1564448C3 (de) 1976-01-02
FI43089B (fi) 1970-10-01
NO119366B (fi) 1970-05-11
BE687198A (fi) 1967-03-21
ES331443A1 (es) 1967-08-01
GB1121035A (en) 1968-07-24
NL6512348A (fi) 1967-03-28
DK118198B (da) 1970-07-20

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