Combined magnetron and ion implantation (CMSII) techn. is currently the only W deposition method that passed demanding thermomechanical tests for the first wall of fusion reactors. CMSII W coated CFC tiles are currently installed in JET and are an option for ITER. We evaluated the unknown hydrogen interaction of such 10um W coatings on Eurofer substrate (two layer membrane) by careful hydrogen permeation measurements and analysis. We extracted all H diffusive trans. param.: diffusivity, solubility and permeability of thin W layer. High solubility was explained by H traps in tungsten layer.
COBISS.SI-ID: 24636967
Hydrogen permeation barrier films often exhibit lower efficiency than anticipated. The cause could be defects in the barrier film, high permeability of the defect-free (dense) barrier film, or a combination of both. This study addresses the recognition of the defects in the hydrogen permeation barrier films using the hydrogen permeation rate transient evolution analysis and suitable mathematical models have been developed. An experimentally useful criterion is derived when and how the permeation through the defects in the barrier layer can be recognized and its extent determined.
COBISS.SI-ID: 24679207
Beryllium films will be used in fusion reactors as the first wall tile coating in the near future. The morphology, adhesion and thermal stability of Be films deposited by the thermionic vacuum arc (TVA) method have been confirmed to be compatible with extremely high thermomechanical demands. Actual Be films used in the future plasma experiments may contain defects causing unwanted porosity which may change the tritium interaction kinetics. Here, we present results of hydrogen permeation at 400°C through 8 micrometer thick Be films deposited by the TVA method on Eurofer membranes.
COBISS.SI-ID: 24629799
For hydrogen permeation measurements through rather impermeable metal membranes it is very challenging to suppress the hydrogen background outgassing flux to the level when it represents only a fraction of the permeation flux. The authors present an innovative thin-walled stainless steel permeation cell design that results in efficient hydrogen background suppression. When implemented in an all metal UHV system, low permeation flux density of hydrogen down to j ~1E−9 mbar L/(cm2 s) could be measured on disk-shaped membranes having an area of 8.4 cm2.
COBISS.SI-ID: 23733287
EUROFER ’97 steel, which has already been chosen for the DEMO reactor, although possessing reduced activation, remains very susceptible to hydrogen. In this study we have looked at the effectiveness of thin, TiAlN coatings with respect to the permeability of hydrogen at 400 °C. Our results reveal that the coating forms a columnar structure, with evidence of epitaxy at the substrate-coating interface, and that this coating can produce a permeation-reduction factor for hydrogen of up to 20,000. This is substantially higher than any other coating reported for this type of steel.
COBISS.SI-ID: 24018471