US2949557A - Equipotential cathode for electric discharge tubes - Google Patents

Equipotential cathode for electric discharge tubes Download PDF

Info

Publication number
US2949557A
US2949557A US765254A US76525458A US2949557A US 2949557 A US2949557 A US 2949557A US 765254 A US765254 A US 765254A US 76525458 A US76525458 A US 76525458A US 2949557 A US2949557 A US 2949557A
Authority
US
United States
Prior art keywords
cathode
tungsten
electric discharge
discharge tubes
wire
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
US765254A
Other languages
English (en)
Inventor
Gerlach Hans Georg
Dorgelo Eduard Gerhardus
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
North American Philips Co Inc
Original Assignee
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 US2949557A publication Critical patent/US2949557A/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
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/28—Dispenser-type cathodes, e.g. L-cathode
    • 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
    • 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
    • H01J1/15—Cathodes heated directly by an electric current
    • 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
    • H01J1/15—Cathodes heated directly by an electric current
    • H01J1/16—Cathodes heated directly by an electric current characterised by the shape
    • 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
    • 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
    • H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes

Definitions

  • This invention relates to tungsten-thorium equipotential cathodes and more particularly to such cathodes having a smooth surface. It also relates to electric discharge tubes, more particularly for short waves, containing such cathodes.
  • tungsten-thorium equipotential cathode may be manufactured by helically winding a wire of this material so that the returns engage one another. The cathode was then covered with tungsten powder and sintered, resulting in a solid tubular body being obtained. By carrying out the sintering process in a special way, it is possible to obtain a structure having a surface as smooth as possible.
  • the sintered cylindrical surface is not sufliciently smooth for very high frequencies.
  • the cylinder is electron-emissive not only on the outer side, but also on the inner side where the heater is situated.
  • the engaging turns of the wire of the tungsten-thorium cathode are wholly covered with a solder on the side adjacent the heater and ground off to half their thickness on the electron-emissive side, so that the cathode has a continuous smooth surface.
  • the solder may consist of the carbide of tungsten, molybdenum, tantalum, orthorium which has a smaller electron-emitting capacity than tungsten-thorium, a melting point of more than 2000 C. and a low vapour pressure. It is possible to add to the carbide a refractory metal in the pulverulent form, for example powdery tungsten by simply mixing the powders with nitro-cellulose, binder to form a paste in order to enhance the roughness of the surface, so as to obtain a good transmission of heat from the heater to the surface of the cathode.
  • the amount of W powder is not critical and may be about equal to the amount of carbide.
  • a suitable paste consists e.g. of 100 g. tungsten-carbide (WC) powder, to which is added a binder, consisting of 30 cc. acetone, 30 cc. diacetone-alcohol and 30 cc. nitrocellulose.
  • WC tungsten-carbide
  • Fig. 1 shows a tube containing a cathode according to the invention of a determined embodiment
  • Fig. 2 shows a detail of the cathode cylinder
  • Figs. 3 and 4 show other embodiments of the cathode.
  • reference numeral 1 indicates the bulb of the tube which is closed by a base 2, into which contact pins 3 are sealed.
  • One of the pins 3 carries rod 4, the upper end 9 of which is connected to a heater 5 and an equipotential cathode 6.
  • the cathode 6 is surrounded by a grid 7 and an anode 8.
  • the cathode 6, as shown in detail in Fig. 2, consists of a tungsten-thorium wire 10 of the usual type employed to make thoriated tungsten cathodes for transmitting type States Patent wound to form a cylinder having a diameter of, for example, 1 cm. and a length of 3 cm., which is covered with soldering material 11.
  • the outer side of the cylinder is ground ofi to half the thickness of the tungsten thorium wire, resulting in a continuous, perfectly smooth tungsten-thorium surface.
  • the surface is constituted by the soldering material 11, which is rough and has a low electron-emitting capacity. Due to the smooth outer surface, the radiation of heat is small, whilst the inner side of the cathode cylinder well absorbs the radiation of heat from the filament 5.
  • the cathode after being ground off, may be carbonized in the usual manner by heating in a vapour of a carbon-hydrogen compound. Dueto the comparatively large wall thickness, the cathode is very well resistant to mechanical shocks.
  • the inner surface of the cylinder may be the electron emitting surface.
  • the cathode which in this case is flat, consists of a tungsten-thorium wire 3, likewise of, for example, 1 mm. in diameter, which is spirally wound to form a disc having a diameter of, for example 1 cm, the disc on the side adjacent the filament 14 being covered with the soldering material 11 and soldered to :a supporting cylinder 12.
  • the filament 14 is mounted on an insulating body 15, for example of ceramic material, which is secured in the supporting cylinder 12.
  • the cylinder 12 may be secured in a discharge tube by means of a flange 13.
  • the heating may take place wholly or in part by bombardment by electrons, if a positive potential with respect to the heating wire 14 is applied to the cathode 10. This is convenient, more particularly for cathodes of large diameter (5 cms.).
  • the heating wire which consists of tungsten, then constitutes together with the lower side of the cathode, a diode.
  • the electron-emissive surface of the cathode is cup-shaped, so that a concentration of electrons may be obtained.
  • the cathode according to the invention may alternatively have other shapes, for example a conical or spherical shape.
  • An indirectly heated equipotential cathode for an electric discharge tube comprising a body formed by a plurality of turns of tungsten thorium wire, adjacent turns of said wire being spaced by a distance substantially less than the diameter of said wire and having adjacent coplanar portions for providing a substantially continuous smooth tubular surface on the outer side of said body, and a layer of a refractory metal solder covering the inner surface of the body and extending between adjacent turns of the wire.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Solid Thermionic Cathode (AREA)
US765254A 1957-10-04 1958-10-03 Equipotential cathode for electric discharge tubes Expired - Lifetime US2949557A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL221344 1957-10-04
NL225825 1958-03-13

Publications (1)

Publication Number Publication Date
US2949557A true US2949557A (en) 1960-08-16

Family

ID=26641626

Family Applications (1)

Application Number Title Priority Date Filing Date
US765254A Expired - Lifetime US2949557A (en) 1957-10-04 1958-10-03 Equipotential cathode for electric discharge tubes

Country Status (7)

Country Link
US (1) US2949557A (es)
BE (1) BE571711A (es)
CH (1) CH366905A (es)
DE (1) DE1063718B (es)
FR (1) FR1204038A (es)
GB (1) GB829339A (es)
NL (1) NL95320C (es)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3262814A (en) * 1960-12-15 1966-07-26 Philips Corp Method for coating an indirectly heated cathode
US3318716A (en) * 1962-09-11 1967-05-09 Pennsalt Chemicals Corp Foam reduction and coating

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1180468B (de) * 1961-04-21 1964-10-29 Siemens Elektrogeraete Gmbh Garraum eines HF-Strahlungsherdes

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2526054A (en) * 1940-03-13 1950-10-17 M O Valve Co Ltd Electrode assembly for very highfrequency electron discharge devices
US2723363A (en) * 1952-04-01 1955-11-08 Gen Electric Cathode and method of producing same

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB582162A (en) * 1940-03-13 1946-11-07 M O Valve Co Ltd Improvements in thermionic valves adapted to operate at very high frequencies

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2526054A (en) * 1940-03-13 1950-10-17 M O Valve Co Ltd Electrode assembly for very highfrequency electron discharge devices
US2723363A (en) * 1952-04-01 1955-11-08 Gen Electric Cathode and method of producing same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3262814A (en) * 1960-12-15 1966-07-26 Philips Corp Method for coating an indirectly heated cathode
US3318716A (en) * 1962-09-11 1967-05-09 Pennsalt Chemicals Corp Foam reduction and coating

Also Published As

Publication number Publication date
NL95320C (es)
CH366905A (de) 1963-01-31
DE1063718B (de) 1959-08-20
GB829339A (en) 1960-03-02
FR1204038A (fr) 1960-01-22
BE571711A (es)

Similar Documents

Publication Publication Date Title
US2543728A (en) Incandescible cathode
US2698913A (en) Cathode structure
US2741717A (en) Dispenser type cathode having gettercoated parts
US2449113A (en) Electric discharge device
US2147447A (en) Glow cathode
US2488731A (en) Electron-emitting electrode for electric discharge tubes
US2501089A (en) Thermionic electron emitter
US2314134A (en) Gaseous discharge device
US2539096A (en) Electron tube and grid for the same
US2438732A (en) Electron tube cathode
US2949557A (en) Equipotential cathode for electric discharge tubes
US2864028A (en) Thermionic dispenser cathode
US2497111A (en) Electron tube having carburized thoriated cathode
US2957100A (en) Magnetron cathode structure
US3041209A (en) Method of making a thermionic cathode
US2210761A (en) Cathode
US2153009A (en) Electric discharge lamp
US2497110A (en) Method of making electrodes
US2684452A (en) Electron tube
US2417460A (en) Nonemissive electrode for electron tube and method of making the same
US2769114A (en) Anode for electron tubes
US2358200A (en) Grid assembly structure
US3221203A (en) Sintered metal conductor support
US2848641A (en) Vapor electric lamp
US3467879A (en) Planar dispenser cathode assembly with a cap member to which an electronemissive,tubular heater,and rodshaped support members are clamped