Surface chemistry and morphology studies of boronized tungsten samples from WEST

WEST is a long-pulse tokamak with a full tungsten first wall and divertor which are conditioned using boron. After the C4 campaign, tiles were extracted from the tokamak in order to perform post-mortem analyses. The analyses will be performed at Penn State with techniques such as depth-profile X-ray Photoelectron Spectroscopy (XPS), Scanning Auger Electron Spectroscopy, Scanning Electron Microscopy, and 3D optical profilometry. With XPS, the chemical composition and stoichiometry of the top 10 nm of a material can be analyzed, while depth profiling enables characterization of compositions from the surface towards the bulk of the material. The focus of these post-mortem analyses will be on characterizing the chemistry and morphology of reconstituted (or redeposited) layers. Reconstituted layers form after repeated high particle and heat flux exposure in tokamak environments. The characteristics of these WEST reconstituted layers will be compared to those of lab-grown boron and tungsten mixed material deposited films, in order to evaluate new ways to study these complex materials. These mixed material films will be deposited and characterized in the new IGNIS-2 facility at Penn State.