DE1273883B - Device for maintaining a constant hydrogen pressure in a negative pressure container, in particular an electrical discharge tube - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN W9W> PATENT OFFICE Int. CL:

G05d

EDITORIAL

German class: 42 q - 1/10

Number: 1273 883

File number: P 12 73 883.9-52 (N 27650)

Filing date: November 16, 1965

Opening day: July 25, 1968

The invention relates to a device for maintaining a constant hydrogen pressure in a vacuum vessel, in particular an electrical discharge tube, with an at elevated temperature Rare earth metal that emits hydrogen and is stored in a separate, electrically heated container is housed.

It is known to use hydrogen-containing metals or metal compounds to keep the hydrogen pressure constant to be used in vacuum vessels. Since the individual parts of the device absorb hydrogen, it is necessary to continuously replenish the amount of hydrogen.

It is known for this purpose to place rare earth metals in a heatable container in a discharge tube accommodate. After venting and degassing the tube, the earth metal is with Hydrogen is saturated, whereupon the tube is melted shut. The difficulty arises with such metals on that their container is severely attacked, since these metals are particularly aggressive. The two known embodiments made of nickel containers therefore have a short service life, especially when the container to the influence of the changing ambient temperature to make the temperature of the hydrogen supplement member sufficiently low, to a temperature is heated from 700 to 800 ° C. In addition, the application of the rare earth metals very favorable, since the pressure of the hydrogen gas of these metals at the temperatures mentioned in in the range of 0.2 to 1 mm mercury pressure is constant, regardless of that present in the metal Amount of hydrogen so that the metal can give off large amounts of hydrogen without the Pressure decreases at the mentioned temperature. Reproducible hydrogen supplement members are thus obtained also in that these metals can be activated better, which in these metals a more uniform hydrogen concentration is achieved.

In order to prevent attack on the container, it has already been proposed to coat the container at least on the inner surface with an oxide of a rare earth metal or to manufacture it entirely from such an oxide. However, such an embodiment has proven useless in practice, since the manufacture is much too complex and difficult for practical use. In addition, the oxide layer of the container can easily break due to the expansion of the underlying nickel, while the device for maintaining one when heated in a vacuum
constant hydrogen pressure in one
Vacuum container, in particular one
electric discharge tube

Applicant:

N. V. Philips' Gloeilampenfabrieken,

Eindhoven (Netherlands)

Representative:

Dr.-Ing. H.-D. Zeller, patent attorney,

2000 Hamburg 1, Mönckebergstr. 7th

Named as inventor:

Placido Reina, Eindhoven (Netherlands)

Claimed priority:

Netherlands of November 20, 1964 (6413 498)

Oxide is atomized, which can then attack the container again.

From many studies it has now shown that the disadvantages mentioned can be avoided if the container for the hydrogen-containing, rare earth metal is made according to the invention from a ceramic material consisting essentially of aluminum oxide and is closed by porous bodies. _{Very pure Al 2} O ₃ is preferably used for the container. The porous bodies can also consist of this ceramic material, but the container is preferably closed by means of plugs made of a thin wire of pure tungsten. It has been found that _{material consisting essentially of Al 0} O ₃ and pure tungsten are not noticeably attacked by the very aggressive metals mentioned.

Rare earth metals are known to mean lanthanum, cerium, praseodymium, neodymium, promethium, Samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, Ytterbium and lutetium.

The invention is explained in more detail with reference to the drawing, which shows a section through an embodiment of a device according to the invention, a so-called hydrogen refill shows.

In the figure, 1 denotes a cylinder made of ceramic _{essentially consisting of Al 0 O.}

809 587/281

Material. Very pure Al ₂ O ₃ is preferably used. The active material 2 consists in this case, for. B. from the rare earth metal lanthanum. Although such metals oxidize more or less rapidly in air, the good effect is not impaired if suitable precautions are taken. The simplest method is that the metal mentioned is applied in the form of lumps or rods.

The cylinder 1 is surrounded by a filament 3 and filled at each end with a porous plug 4, which consists of a thin wire of pure tungsten. The plugs 4 extend into the part of the cylinder 1 which is surrounded by the heating filament 3. The active metal 2 is thus enclosed in the part of the cylinder 1 where a uniform temperature prevails. Since the active substance is surrounded on all sides by the hot tube, it assumes the same temperature everywhere, also as a result of the thermally insulating effect of the container. In this way, a certain hydrogen pressure is achieved without the gas being partially absorbed again by colder parts of the active substance. The hydrogen given off by the metal 2 can escape from the tube 1 through the plugs 4. At the ends of the tube 1 tongues 5 and 6 are attached, which press resiliently against the tube 1 and hold the parts of the container.

The cylinder 1 can have a round cross-section or any other shape. The filament 3 is heated by the supply of current through the lines 10 and 11 so much that the temperature of the active Substance 2 reaches the desired value.

The cylinder 1 is by means of a ceramic disc 7 and a nickel cap 8 in a metal cylinder 9 attached, which is also effective as a heat shield, so that the influence of the ambient temperature is reduced to the temperature of the cylinder 1.

Claims (4)

Patent claims: 1. Device for maintaining a constant hydrogen pressure in a vacuum vessel, in particular, an electric discharge tube, with an at elevated temperature Rare earth metal that emits hydrogen and is stored in a separate, electrically heated container is housed, characterized in that the container (1) consists essentially of aluminum oxide, ceramic material produced and closed by means of one or more porous bodies (4) is. 2. Apparatus according to claim 1, characterized in that the container (1) made of pure Aluminum oxide. 3. Apparatus according to claim 1 or 2 with a tubular, surrounded by a heating coil Container, characterized in that the porous bodies (4) are made from wire plugs Wolframs are made. 4. Hydrogen thyratrone formed according to claim 1, 2 or 3. Considered publications:
U.S. Patent No. 3,095,518. 1 sheet of drawings 809 587/281 7.68 © Bundesdruckerei Berlin