Helium load on W-O coatings grown by pulsed laser deposition

Abstract

W-O deposits with complex morphologies and significant He contents will growth on the surface of plasma facing components exposed to He discharges. To mimic the re/co-deposition process, W-O coatings were loaded with He by implanting He+ ions on W films grown by pulsed laser deposition (PLD). The use of appropriate PLD experimental parameters such as pressurised Ar or He background atmospheres induces the deposition of porous or compact W structures enhancing afterwards the gathering of different amounts of O under exposure to atmospheric air. After multiple ion implantation stages using 150 keV, 100 keV and 50 keV incident He+ ion beams with a total fluence of 5 × 1017 ion/cm2, significant amounts of He were identified in porous coatings by Rutherford backscattering (RBS). Time-of-flight elastic recoil detection (ToF-ERDA) measurements showed that most of the implanted He was already released from the porous coatings five month after implantation, while for the case of compact layers the He content remains significant at deeper layers and smoothly decrease towards the surface, as result of a different morphology and nanostructure. The proposed method involving PLD and ion implantation seems adequate to produce W-O films load by He that may be used as reference samples for fusion investigations.