US3555334A - Cathode with graphite end shields - Google Patents

Cathode with graphite end shields Download PDF

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Publication number
US3555334A
US3555334A US770668A US3555334DA US3555334A US 3555334 A US3555334 A US 3555334A US 770668 A US770668 A US 770668A US 3555334D A US3555334D A US 3555334DA US 3555334 A US3555334 A US 3555334A
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US
United States
Prior art keywords
rings
cathode
magnetron
graphite
end shields
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
US770668A
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English (en)
Inventor
Johannes Antonius Van De Goor
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
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Publication of US3555334A publication Critical patent/US3555334A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/04—Cathodes
    • H01J23/05—Cathodes having a cylindrical emissive surface, e.g. cathodes for magnetrons

Definitions

  • Trifari ABSTRACT A tungsten dispenser cathode for a magnetron is described.
  • the cathode is provided with end shields in the form of solid graphite rings to improve suppression of undesirable electron emission.
  • the invention relates to a magnetron in which the activated part of the cathode which consists of porous tungsten with alkaline earth metal compounds incorporated therein. is mounted or enclosed between rings the surface of which counteracts thermal emission.
  • the rings consist of carbonized or zirconium-coated molybdenum.
  • Barium and/or barium oxide which migrates to said rings from the activated cathode part does not give rise to primary or secondary emissions thereon.
  • the life of the known constructions is not quite satisfactory because under the influence of the high operating temperature the molybdenum carbide decarbonizes and the zirconium difiuses into the molybdenum. The emission-inhibiting properties of the surface of the rings have then disappeared.
  • ring s rings consist of graphite
  • Graphite has not only the property that also when coating the cathode with activating material the thennal emission is extremely low, but also due to the nonsmooth surface the secondary emission is very low. The graphite itself does not experience any change even after prolonged operation at the high cathode temperature.
  • the activated part of the cathode may be coated in known manner with osmium, iridium, ruthenium, rhenium or a similar material to increase the emission or to decrease the temperature. See US. Pat. Nos. 3,373,307 and 3,402,314 re for a more detailed description of the known tungsten dispenser cathodes with and without the emission-increasing coating.
  • FIG. I shows a cathode for a magnetron according to the invention of large continuous power
  • F IG. 2 shows a cathode for a magnetron according to the invention for producing pulses in the millimeter wavelength range.
  • reference numeral 1 denotes a molybdenum tube within which a heater element 2 is arranged.
  • the cylinder 3 is rigidly enclosed or mounted between the rings 4 and 5 of graphite, which likewise readily fit the tube 1.
  • graphite rings 4 and 5 are fixed by the welded narrow molybdenum rings 6 and 7.
  • the diameter of the cylinder 3 is l4mm.
  • the filament power of the element 2 is 200 Watt.
  • a continuous power of 2 KW can be produced with a magnetron provided with the cathode as described above, at a frequency of 2450 mcls.
  • reference numeral 8 denotes a profiled molybdenum body in which the heater element .9 is arranged in the thicker part.
  • the aluminate-impregnated tungsten body 10 which exactly fits around the thinner part of the body 8, is enclosed or arranged between the graphite rings 11 and 12.
  • a molybdenum ring 13 locks the ring 12.
  • a plate 14 of molybdenum terminates the body 8 and supports one end of the heater element 9.
  • the diameter of the body 10 is 2mm.
  • the magnetron is suitable for a frequency of approximately 33Gc/s at which pulses of 2 5 KW peak value can be produced.

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  • Microwave Tubes (AREA)
US770668A 1967-11-03 1968-10-25 Cathode with graphite end shields Expired - Lifetime US3555334A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL676714947A NL153370B (nl) 1967-11-03 1967-11-03 Magnetron waarin het geactiveerde gedeelte van de kathode is opgesloten tussen ringen waarvan het oppervlak thermische emissie tegengaat.

Publications (1)

Publication Number Publication Date
US3555334A true US3555334A (en) 1971-01-12

Family

ID=19801629

Family Applications (1)

Application Number Title Priority Date Filing Date
US770668A Expired - Lifetime US3555334A (en) 1967-11-03 1968-10-25 Cathode with graphite end shields

Country Status (5)

Country Link
US (1) US3555334A (nl)
DE (1) DE1803348A1 (nl)
FR (1) FR1591244A (nl)
GB (1) GB1189940A (nl)
NL (1) NL153370B (nl)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3760214A (en) * 1971-12-30 1973-09-18 Hitachi Ltd Shadow masks for use in colour picture tubes
US3988636A (en) * 1974-04-02 1976-10-26 Hitachi, Ltd. Magnetron with cathode end shields coated with secondary electron emission inhibiting material
US4349424A (en) * 1981-05-15 1982-09-14 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Ion sputter textured graphite

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1897933A (en) * 1928-08-02 1933-02-14 Peoples Gas By Products Corp Electrode for electron discharge tubes and method of forming the same
US2683671A (en) * 1952-07-17 1954-07-13 Westinghouse Electric Corp Low primary and secondary electron emission surface
US3308329A (en) * 1962-11-23 1967-03-07 Litton Industries Inc Thermionic emissive cathode with end structure for emissive suppression

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1897933A (en) * 1928-08-02 1933-02-14 Peoples Gas By Products Corp Electrode for electron discharge tubes and method of forming the same
US2683671A (en) * 1952-07-17 1954-07-13 Westinghouse Electric Corp Low primary and secondary electron emission surface
US3308329A (en) * 1962-11-23 1967-03-07 Litton Industries Inc Thermionic emissive cathode with end structure for emissive suppression

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3760214A (en) * 1971-12-30 1973-09-18 Hitachi Ltd Shadow masks for use in colour picture tubes
US3988636A (en) * 1974-04-02 1976-10-26 Hitachi, Ltd. Magnetron with cathode end shields coated with secondary electron emission inhibiting material
US4349424A (en) * 1981-05-15 1982-09-14 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Ion sputter textured graphite

Also Published As

Publication number Publication date
DE1803348A1 (de) 1969-06-19
NL153370B (nl) 1977-05-16
GB1189940A (en) 1970-04-29
NL6714947A (nl) 1969-05-06
FR1591244A (nl) 1970-04-27

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