Upgraded Pilot-PSI: a new high flux linear plasma device for operando ion beam studies

To investigate dynamic plasma surface interaction processes, we developed the linear plasma generator Upgraded Pilot-PSI (UPP). It couples high-flux plasma exposure with operando ion-beam analysis (IBA) for the first time. UPP generates steady-state hydrogen plasma up to 8.5×1023 m-2 s-1 with electron temperatures ranging from 0.4 to 3.6 eV and densities up to 7.4 × 1019 m-3. Simultaneously, up to 2.8 MeV p, 3He, or 4He ion beams may be used to analyse the top few μm of the material using IBA techniques, allowing the study of hydrogen isotope transport and exchange, dynamic retention, sputtering, and related processes. Alternatively, the ion beam can be used to induce radiation damage in the material while it is simultaneously exposed to plasma, enabling studies of defect stabilisation under plasma conditions. This paper details the design and technical specifications of UPP, focusing on the engineering challenges and solutions involved in integrating operando IBA with a high-flux plasma generator. Our first studies on tungsten exposed to deuterium plasma reveal the mechanism of D transport in the surface (first 0.4 μm) and the bulk (beyond 0.4 μm up to the beam penetration depth) as well as the time to reach saturation.