CH298664A - An electric discharge tube with a tungsten-thorium hot cathode and at least one grid which is provided with a coating which reduces grid emissions. - Google Patents
An electric discharge tube with a tungsten-thorium hot cathode and at least one grid which is provided with a coating which reduces grid emissions.Info
- Publication number
- CH298664A CH298664A CH298664DA CH298664A CH 298664 A CH298664 A CH 298664A CH 298664D A CH298664D A CH 298664DA CH 298664 A CH298664 A CH 298664A
- Authority
- CH
- Switzerland
- Prior art keywords
- grid
- coating
- discharge tube
- thorium
- tungsten
- Prior art date
Links
- 239000011248 coating agent Substances 0.000 title claims description 8
- 238000000576 coating method Methods 0.000 title claims description 8
- WLTSUBTXQJEURO-UHFFFAOYSA-N thorium tungsten Chemical compound [W].[Th] WLTSUBTXQJEURO-UHFFFAOYSA-N 0.000 title claims description 5
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 26
- 229910052697 platinum Inorganic materials 0.000 claims description 13
- 239000000843 powder Substances 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 2
- 238000002844 melting Methods 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- 229910052715 tantalum Inorganic materials 0.000 claims 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 238000003763 carbonization Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 101100400378 Mus musculus Marveld2 gene Proteins 0.000 description 1
- 229910052776 Thorium Inorganic materials 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000003870 refractory metal Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 229910052845 zircon Inorganic materials 0.000 description 1
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 1
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
- H01J19/30—Non-electron-emitting electrodes; Screens characterised by the material
-
- 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
- H01J2893/0019—Chemical composition and manufacture
- H01J2893/002—Chemical composition and manufacture chemical
Landscapes
- Solid Thermionic Cathode (AREA)
Description
Elektrische Entladungsröhre mit einer Wolfram-Thorium-Glühkathode und mindestens einem Gitter, das mit einem die Gitteremission verringernden Überzug versehen ist. Die Erfindung bezieht sich auf eine elek trische Entladungsröhre mit einer Wolfram Thorium-Glühkathode und mindestens einem Gitter, das mit einem die Gitteremission ver ringernden Überzug versehen ist, der wenig stens teilweise aus Platin besteht.
Es ist bereits bekannt, ein Gitter mit einer gegebenenfalls in Kohlenstoff eingebetteten Platinschicht zu versehen und diese Schicht danach mit Kohlenstoff zu überziehen, wobei im Fall einer nicht eingebetteten Schicht so lange geheizt wird, dass das Platin auf der Aussenseite karbonisiert wird.
Soweit, für den Fall, dass das Platin in Kohlenstoff einge bettet und auf der Aussenseite mit einer zu sätzlichen Kohlenschicht versehen ist, das Pla tin nicht absichtlich karbonisiert wird, wird dennoch bei den höheren Betriebstemperatu ren, :die diese Gitterart gewöhnlich annimmt, eine Karbonisierung zwischen dem Platin und der äussern Kohlenstoffsehicht eintreten.
Nach dem absichtlichen Karbonisieren erfolgt ein Ausglühen in Wasserstoff; die Oberfläche wird infolgedessen: glatt, strahlt. somit schlecht und nimmt infolgedessen leicht eine so hohe Tem peratur an, dass trotz des hohen Austritts potentials dennoch etwas primäre Gitteremis sion auftreten kann.
Es ist auch bekannt, Gitter mit Karbiden hochschmelzender Metalle zu überziehen, -was meistens vor dem Einbau in der Röhre durch geführt. wird. Dies hat den Nachteil, dass leicht kleine Beschädigungen der angebrachten Schicht eintreten, wobei :das blanke Gitter material zum Vorschein kommt und sich wäh rend des Betriebes eine verhältnismässig starke primäre Gitteremission ergeben kann.
Die Erfindung bezweckt, die vorstehend erwähnten Nachteile zu vermeiden. Bei einer elektrischen Entladungsröhre mit einer Wolf - ram-Thorium-Glühkathode und mindestens einem Gitter, das mit einem die Gitteremission verringernden-, wenigstens teilweise aus Platin bestehenden Überzug versehen ist, besteht ge mäss der Erfindung dieser Überzug aus einer Platinschicht und einer aufgebrachten,
grauen bis schwarzen Pulverschicht eines hochsebnnel- zenden Metalles, wie zum Beispiel Tautal oder Zirkon.
Die erwähnten hochschmelzenden, Metalle haben infolge ihrer grauen bis schwarzen Pul verform eine gute Strahlungsfähigkeit und halten somit die Temperatur niedrig, wodurch die primäre Gitteremission herabgemindert wird. Die Sekundäremission der erwähnten Stoffe ist auch niedrig, so dass die Gesamt- gitteremission besonders niedrig sein kann.
Ist örtlich die Pulverschicht infolge einer Be schädigung entfernt, so kommt nicht das blanke Gittermaterial zum Vorschein, sondern das Platin, das eine schlechte Primäremission aufweist; ausserdem wird :das Platin durch die starke Strahlung des Pulverüberzuges in der Umgebung kühl gehalten. Wenn vorstehend von Primärgit-teremis- sion die Rede ist, so ist die Primäremission gemeint, die auf eine Aktivierung des Gitters durch Thorium zurückzuführen: ist, das von der Kathode aus auf das Gitter aufdampft.
Die Erfindung wird machstehend an: Hand eines Beispielsnäher erMutert- Das Steuergitter einer Senderöhre besteht aus einem Molybdändraht von 0,;45 mm Stärke. Dieser Draht ist elektrolytisch mit einer Pla tinschicht von 2 ,u überzogen; darüber ist aus einer Suspension feinverteiltes 'Zirkon in 20 ,u Stärke aufgebracht..
Bei einer Gitter belastung von 10 bis 12 W/cin2 ist die Gitter- temperatur etwa 1000 C und die Ge- samtgitteremission beträgt nicht- mehr als 0,2 mAmp./em2.
An electric discharge tube with a tungsten-thorium hot cathode and at least one grid which is provided with a coating which reduces grid emissions. The invention relates to an elec tric discharge tube with a tungsten thorium hot cathode and at least one grid which is provided with a coating which reduces the grid emission and which consists of little at least partially platinum.
It is already known to provide a grid with a platinum layer optionally embedded in carbon and then to coat this layer with carbon, in the case of a non-embedded layer being heated for so long that the platinum is carbonized on the outside.
If the platinum is embedded in carbon and provided on the outside with an additional layer of carbon, the platinum is not intentionally carbonized, but at the higher operating temperatures: that this type of grid usually adopts, carbonization will occur occur between the platinum and the outer carbon layer.
After the deliberate carbonization, annealing takes place in hydrogen; as a result, the surface becomes: smooth, radiant. therefore bad and consequently easily assumes such a high temperature that, despite the high leakage potential, some primary lattice emission can still occur.
It is also known to coat grids with carbides of refractory metals, which is usually done before installation in the tube. becomes. This has the disadvantage that the applied layer is easily damaged, whereby: the bare grid material comes to light and a relatively strong primary grid emission can result during operation.
The invention aims to avoid the disadvantages mentioned above. In the case of an electrical discharge tube with a tungsten-thorium hot cathode and at least one grid that is provided with a coating that reduces grid emissions and is at least partially made of platinum, according to the invention, this coating consists of a platinum layer and an applied,
gray to black powder layer of a high-level metal, such as tautal or zircon.
The above-mentioned high-melting metals have, as a result of their gray to black powder form, good radiation properties and thus keep the temperature low, which reduces the primary lattice emission. The secondary emission of the substances mentioned is also low, so that the overall lattice emission can be particularly low.
If the powder layer is locally removed as a result of damage, it is not the bare grid material that appears, but rather the platinum, which has poor primary emission; In addition: the platinum is kept cool by the strong radiation of the powder coating in the area. When primary grid emission is mentioned above, the primary emission is meant which can be attributed to activation of the grid by thorium: which evaporates onto the grid from the cathode.
The invention is illustrated by: Hand of an example closer erMutert- The control grid of a transmitter tube consists of a molybdenum wire of 0.45 mm thickness. This wire is electrolytically coated with a 2 µ layer of platinum; on top of this, finely divided zirconium in a thickness of 20 u is applied from a suspension.
With a grid load of 10 to 12 W / cin2, the grid temperature is around 1000 C and the total grid emission is no more than 0.2 mAmp./em2.
Claims (1)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL298664X | 1951-02-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CH298664A true CH298664A (en) | 1954-05-15 |
Family
ID=19783116
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CH298664D CH298664A (en) | 1951-02-02 | 1952-01-31 | An electric discharge tube with a tungsten-thorium hot cathode and at least one grid which is provided with a coating which reduces grid emissions. |
Country Status (1)
| Country | Link |
|---|---|
| CH (1) | CH298664A (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
- 1952-01-31 CH CH298664D patent/CH298664A/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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