US1893935A - Highly emissive cathode - Google Patents

Highly emissive cathode Download PDF

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Publication number
US1893935A
US1893935A US545998A US54599831A US1893935A US 1893935 A US1893935 A US 1893935A US 545998 A US545998 A US 545998A US 54599831 A US54599831 A US 54599831A US 1893935 A US1893935 A US 1893935A
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Prior art keywords
barium
cathode
sulphide
highly emissive
sulphate
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Expired - Lifetime
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US545998A
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English (en)
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Emersleben Otto
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    • 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
    • H01J9/042—Manufacture, activation of the emissive part

Definitions

  • the invention relates to a highly emissive with a hydroxyl group).
  • Barium sulphide cathode'and a method ofproducing the same, 'BaS orbarium cyanide (Ba(CN) are exmore particularly according to the metal vaamples of those compounds which result in pour process.
  • 'BaS orbarium cyanide Ba(CN) are exmore particularly according to the metal vaamples of those compounds which result in pour process.
  • cathodes which are prothe necessary mutual decompositions with 5 for example the barium.
  • the sulphide is rials for highly emissive barium cathodes. produced on the cathode itself.
  • the inv ntion relates to another method ner gas-technical, vacuum-technical and oth of activating the barium emission which has er difliculties in manufacture are avoided.
  • ium compounds In addition to barium oxide otherbartoniary in respect of the metal vapour process, ium compounds have proved to be at least barium is so atomized within the valve that equivalent in an electrical respect, while these the same is deposited preferably on the filabarium compounds of other kind disclose adm-ent, this barium itself will act as reducing vantages both as regards the method as well agent in face of the barium sulphate, possibly 49 as certain conditions of emission.
  • potas sium sulphate is more suitable than barium sulphate for application to the cathode, particularly if the same is employ d in the form of potassium bisulphate, KHSOi, which possesses a considerably lower melting point than neutral potassium sulphate.
  • a tungsten filament was in the first place conducted through molten potassium bisulphate produced at 2lO-300 so that the same was coated therewith on the surface.
  • the hydrogen was removed trom the sulphate, for example during the pumping operation, by heating the filament, so that as a whole merely normal sulphate apparently remained on the filament. surface.
  • Barium was thereupon atomized on to the cathode, a barium oxide and aluminium mixture bein applied laterally of the oath ode and heated to the extent of aluminothermal reaction. The barium deposited on the cathode will undoubtedly have reduced the potassium sulphate. Presumably there is formed in this connection an equilibrium of potassium sulphide K 8, barium sulphide BaS, barium oxide Bat) and potassium oxide K 0, in the presence of a considerable excess of metallic barium.
  • a further embodiment of the process according to the invention may consist in s phurating the applied barium by the introduction of small quantities of sulphuretted hydrogen.
  • sulphuretted hydrogen there is formed barium sulphide, while upon the degasifying process not only the excessive sulphurctted hydrogen but also the gases, such as hydrogen, formed upon the reaction may be pumped away.
  • the method is performed in the most suitable manner by at first atomizing a small quantity of barium on to the cathode, then introducing a-small quantity of sulphuretted hydrogen, for example from a sulphuretted hydro gen container, which by means of a three-way tap is connected in a manner permitting the same to be readily shut ofi with the pumping After the introduction of the sulphuretted hydrogen and the subsequent removal of the excess. by pumping, the valve is preferably first sealed and then barium again evaporated, viz., at this stage the essential part of the barium.
  • Electrodes which are not desired to perform emission i. e., in normal threeelectrode 'alves all electrodes with the exception of the cathode, are in this case preferably produced from a metal of that kind which is not, or only to the least possible extent, attached by the sulphuretted hydrogen.
  • molybdenum which in itself is already employed a material for the grids, but which in the present case, according to the additional subject matter of the application, also enters with advantage into consideration as regards a material for the anode.
  • Tungsten may also be employed for electrodes of this kind, whether the same is pure or in the form of an addition or accompanied by additions, which should not be attacked in carrying out the process according to the invention.
  • An additional embodiment of the invention consists in introducing sulphur dioxide S0 into the valve.
  • This possesses in comparison with sulphuretted hydrogen the advantage of not being so very highly reactive. The same does not attack the metals in the valve with the same readiness.
  • nickel electrodes, and more particularly nickel anodes in those valves into which sulphur dioxide is temporarily introduced in performance of the process according to the invention.
  • the sulphur dioxide is mutually decomposed *ith barium oxide in such fashion that equilibrium exists between these two substances on the one hand and barium sulphate and barium sulphide on the other hand.
  • barium sulphate in the manner set forth at the commencement, results by reason of reduction by metallic barium in barium sulphide and new barium oxide.
  • Small amounts of barium oxide which initially are always present if due only to inexactitudes or leakages of the apparatus, are accordingly sufiicient to create fresh quantities of barium oxide which, for the additional course of the process, are essential for maintaining the formation of barium sulphide (in addition to barium oxide) from 1 arium and sulphur dioxide.
  • the invention is not restricted thereto, and may, with correspondingly adapted possibilities of reaction, which in part are somewhat difi'erent in the case of the other materials, be applied to cathodes making use of other light metals, more particularly cathodes composed of calcium or strontium.
  • FIG. 1 shows an electron discharge device containing a plate 1, a grid 2 and a cathode 3.
  • a long tudinal sect on through this cathode 3 is shown on a larger scale in Figure 2.
  • the cathode consists of the cathode body li. e. a wire of tungsten or like metals and the actual emissive layer 5 for instance of barium. Between the wire l and the layer 5 an intermediate layer is provided consisting each according to the selection of the starting material of barium sulphides, barium oxides, etc.
  • a method for manufacturing highly emissive cathodes which consists in coating the surface of the cathode body with a compound of sulphur with a highly emissive metal and that thereon a highly emissive ubstance is deposited in form of metal vapour.
  • a method for manufacturing highly emissive cathodes which consists in coating the cathode body with a compound of sulphur with a highly emissive metal adapted to produce by reactions sulphides of said highly emissive metal and that thereon a highly emissive substance is deposited in form of metal vapour.
  • A. method for manufacturing highly emissive cathodes which consists in coating the cathode body with a compound of sulphur with earth-alkali metals adapted to produce by reactions sulphides of said earthalkali metals and that thereon a highly emissive substance is deposited in form of metal vapour.
  • a method for manufacturing highly emissive cathodes which consists in coating the cathode body with a sulphate of earthalkali metals and that thereon a highly emis- OTTO EMERSLEBEN.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Solid Thermionic Cathode (AREA)
US545998A 1930-06-25 1931-06-22 Highly emissive cathode Expired - Lifetime US1893935A (en)

Applications Claiming Priority (1)

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DE380835X 1930-06-25

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US (1) US1893935A (en(2012))
BE (1) BE380781A (en(2012))
FR (1) FR719069A (en(2012))
GB (1) GB380835A (en(2012))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2861014A (en) * 1956-08-14 1958-11-18 Gen Lab Associates Inc Process of making a semi-conductive ceramic body

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2861014A (en) * 1956-08-14 1958-11-18 Gen Lab Associates Inc Process of making a semi-conductive ceramic body

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Publication number Publication date
GB380835A (en) 1932-09-26
BE380781A (en(2012))
FR719069A (fr) 1932-02-01

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