US2083196A - Heating element for high-voltage cathodes - Google Patents

Heating element for high-voltage cathodes Download PDF

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Publication number
US2083196A
US2083196A US103120A US10312036A US2083196A US 2083196 A US2083196 A US 2083196A US 103120 A US103120 A US 103120A US 10312036 A US10312036 A US 10312036A US 2083196 A US2083196 A US 2083196A
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United States
Prior art keywords
heating element
cathodes
layer
rod
furnished
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Expired - Lifetime
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US103120A
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English (en)
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Liebmann Gerhard
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Individual
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Individual
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    • 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

Definitions

  • high-voltage cathodes are understood to be cathodes which may be heated by the mains in direct fashion without the interposition of throttling resistances, or at least those 5 in which by the series connection of a few cathodes of this nature it is accomplished that the full mains voltage may be applied thereto. Since present-day high-emission cathodes require merely a small heating output, the heating element of the cathode may be furnished with a high resistance for the purpose of obtaining very small intensity of the heating current.
  • a novel and fundamentally different method according to the invention consists in the fact that in place of the very thin and long metallic wire there is employed a straight semi-conductor rod.
  • the heating element according to the invention consists of a very thin ceramic rod (for example, aluminum oxide), which is coated with a thin layer of so-called hard carbon.
  • This hard-carbon layer is produced by the decomposition of benzole vapour at high temperature and may be regulated practically withindesired limits by selection of the temperature, the gas pressure and the period of reaction. It is quite readily possible in accordance with this process to produce cathodes which, with the dimensions usual at the present time, may be heated in direct fashion by lighting mains of 220 V.
  • the method of producing this layer of carbon is known per se.
  • the deposit may be obtained, for example, by introducing the ceramic rods to be treated into a refractory furnace pipe, which has been evacuated and filled with benzole vapor, whereupon the entire receptacle is heated over a lengthy evenly through a short heating zone.
  • the rods to be treated may also be allowed to rotate.
  • the known methods for the continuous application of carbon there may also be employed the known methods for the continuous application of carbon.
  • any other suitable hydrocarbon in the same manner as it is also possible to allow the current of hydrocarbon to flow through the reaction vessel, whereby it may also be diluted with a neutral gas.
  • a separately introduced heating element to employ the small insulating tube contained in the majority of cathodes as support for the layer of carbon, the deposit of car bon being produced on its interior.
  • the procedure may be such that an insulating tube of, say, 1 metre in length is' traversed by benzole vapor with preclusion of the air whilst the entire tube is being moved At the hot points there occurs a deposition of carbon within the tube.
  • the long tube coated with carbon on the inside is later cut to the desired length.
  • the carboncoated heating elements are furnished preferably with clamped on shoes, whereby the contact resistance may be decreased by an intermediate layer of graphite or by a metallic coating.
  • Cathodes having the described heating elements are distinguished by a particularly even temperature. If it is desired to keep the ends of the cathode cool, this may be readily accomplished by extending the metallic coating at the ends.
  • the heating rod commences to glow only proceeding from the end of the metallic coating.
  • Fig. 1 is a sectional view along the axis and Fig. 2 a sectional view cut vertically to the axis, while Fig. 3 shows a modification in a sec tion vertically to the axis.
  • Figs. 2 and 3 show the ceramic support I having the layer of hard carbon 1, whereby in Fig. 2 the hard-carbon layer is applied to the outside, whilst in Fig. 3 it is provided in the interior of the small tube.
  • a highly emissive cathode of the indirectly heated type consisting of a tubular semi-conductor rod of ceramic material furnished over its entire length with a hard carbon layer and furnished at the ends of the cylindrical surface with metallic coatings to which metallic connecting caps are fitted, a second insulating tubular rod fitted over said first rod, said second rod being furnished with an equipotential layer and a highly emissive layer.
  • a highly emissive cathode of the indirectly heated type consisting of a tubular semi-conductor rod of ceramic material furnished over its entire length on the outside with a hard carbon layer and furnished at the ends of the cylindrical surface with metallic coatings to which metallic connecting caps are fitted, a second insulating tubular rod fitted over said first rod, said second rod being furnished with an equipotential layer and a highly emissive layer.
  • a highly emissive cathode of the indirectly heated type consisting of a small insulating tubular rod of ceramic material furnished over its entire length in the interior with a hard carbon layer and furnished at the ends of the inner cylindrical surface with metallic coatings, to which metallic coating caps are fitted, said rod being furnished at the outer surface with an equipotential layer and a highly emissive layer.

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  • Furnace Details (AREA)
  • Solid Thermionic Cathode (AREA)
  • Resistance Heating (AREA)
US103120A 1935-10-02 1936-09-29 Heating element for high-voltage cathodes Expired - Lifetime US2083196A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DER94368D DE724812C (de) 1935-10-02 1935-10-02 Heizelement fuer indirekt geheizte Hochvoltkathoden

Publications (1)

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US2083196A true US2083196A (en) 1937-06-08

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ID=7419148

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US103120A Expired - Lifetime US2083196A (en) 1935-10-02 1936-09-29 Heating element for high-voltage cathodes

Country Status (5)

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US (1) US2083196A (fr)
DE (1) DE724812C (fr)
FR (1) FR811528A (fr)
GB (1) GB474179A (fr)
NL (1) NL47731C (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528425A (en) * 1950-10-31 Electron tube cathode heater
US2563573A (en) * 1951-08-07 Hot cathode electron tube which re
US2817605A (en) * 1947-03-24 1957-12-24 Manuel C Sanz Method for sealing the pores in a carbon body
US3307974A (en) * 1962-03-19 1967-03-07 Rank Radio And Television Ltd Method of forming thermionic cathodes
US3479551A (en) * 1966-09-26 1969-11-18 Atomic Energy Authority Uk Electron emitting cathodes having a flexible graphite filament with an emissive coating thereon
US3534218A (en) * 1967-03-30 1970-10-13 Atomic Energy Authority Uk Electron emitting cathodes for irradiation machines

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110218987A (zh) * 2019-07-24 2019-09-10 合肥百思新材料研究院有限公司 一种冷壁法cvd沉积设备及其工作方法

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528425A (en) * 1950-10-31 Electron tube cathode heater
US2563573A (en) * 1951-08-07 Hot cathode electron tube which re
US2817605A (en) * 1947-03-24 1957-12-24 Manuel C Sanz Method for sealing the pores in a carbon body
US3307974A (en) * 1962-03-19 1967-03-07 Rank Radio And Television Ltd Method of forming thermionic cathodes
US3479551A (en) * 1966-09-26 1969-11-18 Atomic Energy Authority Uk Electron emitting cathodes having a flexible graphite filament with an emissive coating thereon
US3534218A (en) * 1967-03-30 1970-10-13 Atomic Energy Authority Uk Electron emitting cathodes for irradiation machines

Also Published As

Publication number Publication date
FR811528A (fr) 1937-04-16
NL47731C (fr) 1940-02-15
GB474179A (en) 1937-10-27
DE724812C (de) 1942-09-05

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