DE467674C - Rectifier, consisting of a discharge vessel with a glow cathode - Google Patents

Description

Patent specification 440 044 describes a hot cathode rectifier consisting of a discharge vessel described, whose hot cathode consists of tungsten or another metal, which at temperatures of at least 2,000 ° C has not yet melted, and its atomization by a filling of Nitrogen, argon or mercury at a sufficiently high gas pressure (some Millimeters to a few centimeters) is prevented or reduced. It has now been found that in such a discharge vessel there is a noticeable reduction in the voltage drop can be achieved in the arc if small amounts of a substance such. B. Calcium and the relatives Alkaline earth metals, magnesium, or non-metallic absorbents, such as ζ. Β. Phosphorus pentoxide, which are while it does not act chemically on the gas filling, acts chemically on impurities in the latter and with them Forms compounds of negligibly low vapor pressure. In the case of a filling of the Rectifiers with argon seem to be the most dangerous gaseous contaminants try to increase the voltage drop in the arc, water vapor, hydrogen and to be nitrogen.

The chemically active substance that reacts to harmful gaseous impurities the gas filling or harmful gases contained in the electrodes or in the vessel wall acts, can be evaporated through the cathode if it is in the passage of current to the Glow is brought, or it can simply be in any suitable way in the vessel be housed. For example, metallic calcium or magnesium can be in the form from narrow strips or wires to one of the lead wires of the cathode, namely close to the cathode, pushed or wrapped so that it is heated by the sides evaporate from the arc or the hot cathode. The chemical additive can also be used within the discharge vessel in one thin-walled glass capsule, which after melting the tube broken by shaking.

When filling with nitrogen,

preferably phosphorus pentoxide to absorb water vapor and other gaseous forms Suitable for impurities. When filling with monatomic gases, e.g. B. argon, neon, Krypton, xenon or helium, calcium, magnesium, or a related one is particularly suitable Metal. Calcium vapor absorbs all gases with the exception of the very inert monatomic ones Gases. However, phosphorus pentoxide can also be used successfully to purify a single-atom gas filling in the vessel itself will. Phosphorus pentoxide removes hydrogen and water vapor from the argon filling and to some extent nitrogen. Part of the pentoxide becomes reduced by the hydrogen and forms water vapor, which then by the rest Pentoxide is absorbed and forms gummy phosphoric acid of very low vapor pressure.

The beneficial effect of the cleaning agents to be used according to the invention achieved, must not start with the chemical cleaning of the filling gas before its' Introduction to the discharge vessel can be confused. The one inside the discharge vessel in contact with its gas filling Any chemically active substance brought in has, in addition to cleaning the gas filling, in the - At the start of operation, the effect of continuously absorbing traces of harmful gases are released from the electrodes and the vessel wall during operation. 'Obvious The arc activates the gaseous contaminants so that they can interact with the chemical vapor within the Connect the tube more easily.

Applying the latter can reduce the voltage drop to half and in in some cases even more reduced compared to discharge vessels, their Gas filling before introduction into the discharge vessel in the most careful manner has been purified using known chemical methods. For example, one 6 amp rectifier with one in the ordinary Wise purified argon filling found a voltage drop of 30 to 40 volts, which was reduced to about 10 volts when in accordance with the invention phosphorus pentoxide was introduced into the discharge vessel. Similarly, with a 6 amp tube, the one in the usual Way purified neon filling of about half atmospheric pressure contained a voltage drop of about 50 volts, on the other hand, after the introduction of metallic calcium, only one of about 20 volts was found.

This can result in an even further reduction in the voltage drop in the arc be achieved that the anode itself consists wholly or partly of a chemically very active metal, for. B. Calcium: Magnesium or titanium.

An exemplary embodiment for a discharge vessel of the latter type is shown in the figure shown. The vessel 1 consists of a glass of small size, e.g. B. made of sodium magnesium brosilicate glass. The cathode 2 consists of a very heat-resistant Fabric, e.g. B. A tungsten, tantalum,. Carbon or the like. The anode 3 consists of metallic calcium, magnesium, titanium or any other metal that opposes each other the gases, apart from the noble gases, are chemically very active. The cathode gets electricity through the wires 4 and 5 are fed to the anode through the wire 6. These wires are in the fused into feet 7 and 8 in the usual way. The cathode preferably has a glow head 9 of slightly larger diameter, as described in the additional patent specification 442,276. The tube is first vented and then filled with a monatomic gas to a considerable pressure. the Choosing the anode material makes it unnecessary to take as much care as before when venting apply. The gas pressure fluctuates depending on the type of discharge vessel and its task; it can be a few millimeters of Hg to about atmospheric pressure. With the arrangement described, the voltage loss be pushed down to 4 or 5 volts.

The advantageous effect of the invention should be illustrated by the following examples, which relate to discharge vessels with calcium anodes. With an argon filling at a pressure of approximately 1/2 to 12 cm Hg, an 8 ampere arc with a voltage drop of 10.4 volts could be generated with an incandescent cathode. After three hours of operation, the voltage drop had dropped to 7.8 volts. An initial voltage drop of 6.9 volts was observed with a 20 ampere arc, which had dropped to 4.5 volts after three hours of operation. In a purified in the usual manner neon fill of about ¹ I ₄ atmospheric pressure, a voltage drop of approximately 58 volts, for a 10-Ämpere arc initially observed, which sank in about 40 minutes to about 12.5 volts.

Another advantage of using anodes made of chemically very active metals is their extremely low chip resistance. voltage required to ignite the arc. For example, a 15 ampere arc can be used in conjunction with a cathode whose temperature is 2500 ^{° C.}

can be ignited with a voltage of only 14 volts.

It should be noted "that the means described here are in themselves already used to produce a high vacuum or for cleaning gas residues in vacuum tubes are known. It is also known that j the gas residues of the cathode fall is greatly reduced, z. B. in argon up to 120 volts (see red t gar dt, annals of the Physics, 4th episode, volume 33, 1910, page 1185). In the present case, these means are applied to the rectifier according to the main patent, whose total voltage drop is already significantly lower than the aforementioned cathode drop of 120 volts, and this voltage drop is further significantly reduced, making this rectifier in trained in a particularly expedient manner

ao will.

Claims (2)

Patent claims: 1. Rectifier, consisting of a discharge vessel with hot cathode according to Patent 440 044, characterized in that in otherwise known manner in the vessel a small amount of one Substance is present which does not have any chemical effect on the gas filling, on the other hand acts on impurities of the latter and forms with them compounds of very low vapor pressure, e.g. B. Phosphorus pentoxide with nitrogen filling or alkaline earth and similar metals Filled with monatomic gases. 2. Rectifier according to claim 1, characterized in that in otherwise As is known, the anode itself consists of calcium, magnesium, titanium or a similar metal. 1 sheet of drawings