Tungsten nitride coatings obtained by HiPIMS as plasma facing materials for fusion applications

Abstract

In this work, tungsten nitride coatings with nitrogen content in the range of 19–50 at% were prepared by reactive multi-pulse high power impulse magnetron sputtering as a function of the argon and nitrogen mixture and further exposed to a deuterium plasma jet. The elemental composition, morphological properties and physical structure of the samples were investigated by Rutherford backscattering spectrometry, atomic force microscopy and X-ray diffraction. Deuterium implantation was performed using a deuterium plasma jet and its retention in nitrogen containing tungsten films was investigated using thermal desorption spectrometry. Deuterium retention and release behaviour strongly depend on the nitrogen content in the coatings and the films microstructure. All nitride coatings have a polycrystalline structure and retain a lower deuterium level than the pure tungsten sample. Nitrogen content in the films acts as a diffusion barrier for deuterium and leads to a higher desorption temperature, therefore to a higher binding energy.