Abstract: The process for making a structural element subjected to a high thermal stress and made of a material of high thermal conductivity such as molybdenum, tungsten, copper, aluminum or an alloy of these metals with a protective layer protecting the surface of the structural element comprises treating the surface of the structural element to remove surface impurities present and then coating the surface with an amorphous hydrogen containing carbon layer. For reduction, i.e. removal, of the surface impurities the structural element can advantageously be exposed to a hydrogen flow containing hydrogen atoms and/or ions at a temperature of from 100.degree. C. to 600.degree. C. at a pressure of from 10.sup.-2 to 10.sup.2 Pa. The hydrogen atoms and/or the hydrogen ions coming in contact with the surface of the structural element are formed by contact dissociation at at least one hot surface or by glow discharge or by electron cyclotron resonance and the volatile products are pumped away.

Abstract: In separating hydrogen from a mixture of gases by diffusion through a non-porous membrane which is selectively permeable to hydrogen, the hydrogen being at least partially dissociated prior to being contacted with the membrane, the membrane is made up of at least two layers of different materials. The layer on the upstream side of the membrane is less dissolving to hydrogen and has a lower release rate constant at 300.degree. C. than the layer on the downstream side. The membrane may consist of an iron diaphragm with a thin coating of copper on the upstream side.

Abstract: An apparatus utilized for separating hydrogen isotopes from a gas mixture separate isotopes contained in a hydrogen isotope mixture. The apparatus is provided with two chambers closable by valves and surrounded on all sides by walls and separated from each other by a wall or partition of material differing from palladium though permeable preferably for atomic hydrogen and permeable only to a lesser extent for molecular hydrogen. One of the chambers is connected with a gas supply line as well as a gas discharge line, and the other chamber, provided for collecting isotope mixture coming through the permeable wall, is capable of being evacuated. The remaining walls of the chambers consist of material which is not or is only poorly permeable for hydrogen isotopes.

Abstract: Molecular hydrogen is caused to flow past a hot filament and then past an article having surfaces which are to be cleaned located in a vacuum chamber, at a pressure such that the mean free path of hydrogen molecules is less than the minimum space between the surfaces to be cleaned and the walls of the container. Some of the hydrogen molecules are converted by the hot filament into hydrogen atoms, which react with contaminants on the surface to be cleaned to form products that can be removed by the flow of gas. Other devices can be used for dissociating hydrogen flowing into the chamber into hydrogen atoms and/or ions. Cleaning is effective even on surfaces facing away from the location where the hydrogen atoms are formed.