US3753025A - Indirectly heated supply cathode - Google Patents

Indirectly heated supply cathode Download PDF

Info

Publication number
US3753025A
US3753025A US00203705A US3753025DA US3753025A US 3753025 A US3753025 A US 3753025A US 00203705 A US00203705 A US 00203705A US 3753025D A US3753025D A US 3753025DA US 3753025 A US3753025 A US 3753025A
Authority
US
United States
Prior art keywords
base plate
cathode
emissive body
sintered
indirectly heated
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
US00203705A
Other languages
English (en)
Inventor
Stratum A Van
S Loyen
Os J Van
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
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 US3753025A publication Critical patent/US3753025A/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

Definitions

  • the invention relates to an indirectly heated supply cathode consisting of a sintered emissive body which is surrounded by a metal jacket and is supported by a metal base plate.
  • the invention relates in particular to a supply cathode having a large diameter and a comparatively small thickness.
  • the emissive body consists, for example, of a layer of barium aluminate and tungsten and a porous tungsten body or consists entirely of such a mixture of barium aluminate power and t tungsten powder.
  • Such cathode which layers are compressed and sintered have the drawback that it is not possible to increase the diameter without also increasing the thickness of the emissive body, since otherwise the mechanical rigidity of the cathode becomes too small since the sintered emissive body is brittle.
  • a thin sintered disc-shaped emissive body therefore is very fragile.
  • the sintered disc does not remain flat but warps as a result of heating and cooling during operation and then becomes located loosely in the jacket as a result of which moreover the electric contact with the jacket is impaired.
  • an indirectly heated cathode consisting of a sintered emissive body which is surrounded by a jacket and is supported by a metal base plate if, according to the invention, the base plate is provided with a number of metal pins which are embedded at least for part of their length in the emissive body.
  • the heating element may be provided in known manner on the other side of the base plate, but a cheaper construction is obtained if the heating element is positioned between the sintered emissive body and the base plate.
  • FIGS. 1, 2 and 3 show various embodiments of cathodes according to the invention.
  • reference numeral 1 denotes a metal jacket which in this case comprises a base 11.
  • the jacket 1 with the base 11 consists, for example, of molybdenum and can be obtained by turning or pressing.
  • a heating wire 4 is provided in an insulated manner on the base 11 in that the wire 4 is embedded in a layer of aluminium oxide powder 9.
  • the ends 5 of the heating wire 4 are covered with an insulating layer and pass through the bore 11.
  • the metal base plate 2, which supports the emissive body 8, is provided with a number of metal pins 3 which are secured in the base plate 2 and are embedded in the sintered emissive body 8. In this manner it has proved to be possible to avoid deformation of the emissive body 8.
  • the cathode may have any large diameter without it being necessary to increase the thickness.
  • the base plate 2 and the pins 3 may consist of molybdenum.
  • FIG. 2 A cheaper construction is shown in FIG. 2.
  • the base plate 2 with the pins 3 also form the bottom of the ring 1.
  • the base plate 2 is, for example, pressed in the turned ring 1 and clamped.
  • the heating wire 4 which is covered with a thin layer of alumina is laid between the pins 3, for example, in a zig-zag manner or as a coiled coil and is covered with alumina powder 9.
  • alumina powder 9 On this powder the preferably granulated powdered mixture of barium aluminate and tungsten is poured and the assembly is compressed until the layer has a density of from to 90 percent and is then sintered.
  • the pins 3 are embedded in the emissive body 8 and prevent warping of the emissive body.
  • the thickness of the disc-shaped cathode is considerably smaller than that of the cathode shown in FIG. 1. Since the cathode has a smaller mass, the heating time is comparatively short.
  • a layer 6 consisting of a mixture of tungsten and barium-calcium aluminate powder and on top of this a layer 7 consisting of tungsten powder is provided on the aluminium oxide layer 9 of the heating element.
  • the layers are compressed and at the same time sintered, as in FIG. 2.
  • the upper surface of the emissive body of the cathodes shown in FIGS. 1, 2 and 3 is covered, preferably prior to sintering, with an osmium layer, preferably by sputtering, which osmium layer is then also sintered.
  • the jacket 1, the base plate 2 and the pins 3 preferably consist of molybdenum.
  • the base plate 2 may also consist of compressed and sintered metal powder, in which compression and sintering can be car ried out simultaneously with the compression and sintering of the remaining layers.
  • the outside diameter of the cathode is 2 cm, the thickness is 3 mm, and pins are provided.
  • the thickness of the emissive body is substantially independent of the diameter.
  • the jacket 1 need not consist of metal.
  • Cathodes according to the invention are particularly suitable for disc triodes and tubes which operate with large current densities.
  • An indirectly heated supply cathode comprising a. a metal base plate;
  • heating means comprises a heating element located between said base plate face and said emissive body, said heating element being located between and electrically insulated from said pins.

Landscapes

  • Powder Metallurgy (AREA)
  • Solid Thermionic Cathode (AREA)
US00203705A 1970-12-10 1971-12-01 Indirectly heated supply cathode Expired - Lifetime US3753025A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7018001A NL7018001A (en(2012)) 1970-12-10 1970-12-10

Publications (1)

Publication Number Publication Date
US3753025A true US3753025A (en) 1973-08-14

Family

ID=19811756

Family Applications (1)

Application Number Title Priority Date Filing Date
US00203705A Expired - Lifetime US3753025A (en) 1970-12-10 1971-12-01 Indirectly heated supply cathode

Country Status (6)

Country Link
US (1) US3753025A (en(2012))
CA (1) CA934431A (en(2012))
DE (1) DE2157768A1 (en(2012))
FR (1) FR2117650A5 (en(2012))
GB (1) GB1327975A (en(2012))
NL (1) NL7018001A (en(2012))

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4147954A (en) * 1976-07-10 1979-04-03 E M I-Varian Limited Thermionic electron emitter
US4379979A (en) * 1981-02-06 1983-04-12 The United States Of America As Represented By The Secretary Of The Navy Controlled porosity sheet for thermionic dispenser cathode and method of manufacture
US5118983A (en) * 1989-03-24 1992-06-02 Mitsubishi Denki Kabushiki Kaisha Thermionic electron source
US5350969A (en) * 1991-12-03 1994-09-27 Litton Systems, Inc. Cathode heater and cathode assembly for microwave power tubes
US5451831A (en) * 1992-06-27 1995-09-19 Goldstar Co., Ltd. Impregnated pellet for a cathode structure and method of producing the same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2798182A (en) * 1951-07-12 1957-07-02 Siemens Ag Dispenser cathode having heater embedded in densely sintered receptacle wall
US3117249A (en) * 1960-02-16 1964-01-07 Sperry Rand Corp Embedded heater cathode
US3432715A (en) * 1966-03-22 1969-03-11 Commissariat Energie Atomique Composite electrode for mhd conversion duct

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2798182A (en) * 1951-07-12 1957-07-02 Siemens Ag Dispenser cathode having heater embedded in densely sintered receptacle wall
US3117249A (en) * 1960-02-16 1964-01-07 Sperry Rand Corp Embedded heater cathode
US3432715A (en) * 1966-03-22 1969-03-11 Commissariat Energie Atomique Composite electrode for mhd conversion duct

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4147954A (en) * 1976-07-10 1979-04-03 E M I-Varian Limited Thermionic electron emitter
US4379979A (en) * 1981-02-06 1983-04-12 The United States Of America As Represented By The Secretary Of The Navy Controlled porosity sheet for thermionic dispenser cathode and method of manufacture
US5118983A (en) * 1989-03-24 1992-06-02 Mitsubishi Denki Kabushiki Kaisha Thermionic electron source
US5350969A (en) * 1991-12-03 1994-09-27 Litton Systems, Inc. Cathode heater and cathode assembly for microwave power tubes
US5451831A (en) * 1992-06-27 1995-09-19 Goldstar Co., Ltd. Impregnated pellet for a cathode structure and method of producing the same

Also Published As

Publication number Publication date
FR2117650A5 (en(2012)) 1972-07-21
NL7018001A (en(2012)) 1972-06-13
DE2157768A1 (de) 1972-06-29
CA934431A (en) 1973-09-25
GB1327975A (en) 1973-08-22

Similar Documents

Publication Publication Date Title
US3260880A (en) Electro-optical indicator devices with multiple anodes for each cell
US2731578A (en) Electron tube
US4053807A (en) Thermionic cathode and heater structure on ceramic base plate
US3753025A (en) Indirectly heated supply cathode
US2899590A (en) Ceramic vacuum tube
US3297902A (en) Electron discharge device having a laminated and finely reticulated grid structure therein
US3231776A (en) Display device
JPH07147127A (ja) 異方性の熱分解グラファイトヒーター
US3528156A (en) Method of manufacturing heated cathode
US2740067A (en) Ceramic vacuum tube
US3638062A (en) Support for composite electrode structure
US3113236A (en) Oxide dispenser type cathode
US2754445A (en) Ceramic vacuum tube
US4013912A (en) Gas mixture for glow discharge device
US3776613A (en) Gas-discharge display panel
US5507675A (en) Method of manufacturing a thermionic cathode structure
US3754882A (en) Method of manufacturing a light conductive perforated plate
US2910607A (en) Ceramic type electron tube
US3175118A (en) Low power heater
US3495120A (en) Microheating elements,more particularly for cathodes of electron tubes
US2197526A (en) Support for electrodes
US2786957A (en) Emissive cathodes
US3684909A (en) Display panel having particle source
JPS59196541A (ja) 電子増倍器及び該電子増倍器を具えた放射線検出装置
US2713532A (en) Electron tube and method of making the same