CH298665A - Electric discharge tube with at least one grid made of refractory metal. - Google Patents
Electric discharge tube with at least one grid made of refractory metal.Info
- Publication number
- CH298665A CH298665A CH298665DA CH298665A CH 298665 A CH298665 A CH 298665A CH 298665D A CH298665D A CH 298665DA CH 298665 A CH298665 A CH 298665A
- Authority
- CH
- Switzerland
- Prior art keywords
- discharge tube
- electric discharge
- grid
- refractory metal
- bars
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
- H01J19/28—Non-electron-emitting electrodes; Screens
- H01J19/38—Control electrodes, e.g. grid
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2893/00—Discharge tubes and lamps
- H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
- H01J2893/0012—Constructional arrangements
- H01J2893/0015—Non-sealed electrodes
Description
Elektrische Entladungsröhre mit mindestens einem Gitter aus hochschmelzendem Metall. Die vorliegende Erfindung betrifft eine elek trische Entladungsröhre mit mindestens einem Gitter aus hochschmelzendem Metall, wie Wolf ram, Molybdän und Tantal.
Zur Verhütung von Gitteremission sind verschiedene Belegungen des Gitters bekannt, die aus Platin, karbonisiertem Platin, Kohlen- stoff, Karbiden aus hochschmelzenden Metal len, gepulverten hochschmelzenden Metallen oder dergleichen bestehen.
Bei Senderöhren von einigen 100 kW ist die Schwierigkeit jedoch die, dass die aufgebrachten Pulverschichten beim Auftreten besonders hoher Gittertemperaturen allmählich zu einer glatten Schicht zusammen sintern, bei der die Gittertemperatur hoch wird und somit, besonders unter der Einwirkung gegebenenfalls von der Kathode verdampften Thoriums, wenn eine Wolframthoriumkathode vorhanden ist, leicht Gitteremission eintritt.
Die Erfindung sucht ein Gitter zu schaffen, das auch nach langer Betriebsdauer eine gute Abstrahlung behält und somit auch bei hoher Belastung wenig Primäremission aufweist.
Bei einer elektrischen Entladungsröhre mit mindestens einem Gitter aus hochschmelzen dem Metall bestehen gemäss der Erfindung die Gitterstäbe aus einem Gefüge feiner Drähte. Die Gitterstäbe können z. B. aus sogenanntem Litzendraht oder aus einem massiven Kern draht bestehen, der mit einer Oberflächenschicht aus feinen Drähten versehen ist, die parallel zu der Richtung des Gefüges verlaufen oder mit grosser Steigung wendelförmig gewickelt sind. Infolge der verhältnismässig rauhen Oberfläche, die von den feinen Drähten gebildet wird, ist die Strahlung des Gitters besonders gut, so dass auch bei Aufdampfen des Thoriums von der Kathode her infolge der niedrigen Gittertem peratur nur wenig primäre Gitteremission auf tritt.
Die Erfindung wird nachstehend an Hand eines Ausführungsbeispiels näher erläutert. Bei einer Senderöhre von 20 kW wurden die Gitterstäbe aus einem Gefüge von 7 Wendel förmig ineinandergedrehten Wolframdrähten von 0,25 mm Durchmesser hergestellt. Bei die ser Röhre war für die gleiche Gittertemperatur der zulässige Gitterverlust annähernd um 30 /o höher, als wenn ein glatter Gitterdraht von den gleichen äussern Ausmassen benutzt wurde.
Electric discharge tube with at least one grid made of refractory metal. The present invention relates to an elec tric discharge tube with at least one grid made of refractory metal, such as Wolf ram, molybdenum and tantalum.
To prevent grid emissions, various grids are known which consist of platinum, carbonized platinum, carbon, carbides from high-melting metals, powder-coated high-melting metals or the like.
In the case of transmission tubes of a few 100 kW, however, the difficulty is that the powder layers applied gradually sinter together to form a smooth layer when particularly high lattice temperatures occur, at which the lattice temperature becomes high and thus thorium, especially under the influence of the cathode, may evaporate if a tungsten thorium cathode is present, lattice emission easily occurs.
The invention seeks to create a grille that retains good radiation even after a long period of operation and thus has little primary emission even under high loads.
In an electrical discharge tube with at least one grid made of high-melting metal, according to the invention, the bars consist of a structure of fine wires. The bars can, for. B. consist of so-called stranded wire or a solid core wire, which is provided with a surface layer of fine wires that run parallel to the direction of the structure or are helically wound with a steep slope. As a result of the relatively rough surface that is formed by the fine wires, the radiation of the grid is particularly good, so that even with vapor deposition of the thorium from the cathode, only few primary grid emissions occur due to the low grid temperature.
The invention is explained in more detail below using an exemplary embodiment. With a transmission tube of 20 kW, the bars were made from a structure of 7 helically twisted tungsten wires with a diameter of 0.25 mm. In the case of this tube, for the same grid temperature, the permissible grid loss was approximately 30 / o higher than when a smooth grid wire of the same external dimensions was used.
Claims (1)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL298665X | 1951-02-05 |
Publications (1)
Publication Number | Publication Date |
---|---|
CH298665A true CH298665A (en) | 1954-05-15 |
Family
ID=19783117
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CH298665D CH298665A (en) | 1951-02-05 | 1952-02-04 | Electric discharge tube with at least one grid made of refractory metal. |
Country Status (1)
Country | Link |
---|---|
CH (1) | CH298665A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1021502B (en) * | 1956-02-01 | 1957-12-27 | Philips Nv | Process for producing electrodes with low thermal emission for electrical discharge tubes and electrical discharge tubes with at least one electrode produced by this process |
DE1051991B (en) * | 1956-10-29 | 1959-03-05 | Philips Nv | Process for producing an electrical discharge tube with at least one electrode with low thermal emission and electrical discharge tubes produced by this process |
-
1952
- 1952-02-04 CH CH298665D patent/CH298665A/en unknown
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1021502B (en) * | 1956-02-01 | 1957-12-27 | Philips Nv | Process for producing electrodes with low thermal emission for electrical discharge tubes and electrical discharge tubes with at least one electrode produced by this process |
DE1051991B (en) * | 1956-10-29 | 1959-03-05 | Philips Nv | Process for producing an electrical discharge tube with at least one electrode with low thermal emission and electrical discharge tubes produced by this process |
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