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P: Fachverband Plasmaphysik

P 3: Plasma Wall Interactions I / Astrophysical Plasmas

P 3.1: Vortrag

Montag, 5. März 2018, 14:00–14:15, A 0.112

Impact of steady state deuterium plasmas on WCrY Smart Alloys — •Janina Schmitz^1,2, Andrey Litnovsky¹, Felix Klein¹, Tobias Wegener¹, Xiao Yue Tan¹, and Christian Linsmeier¹ — ¹Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich, Germany — ²Department of Applied Physics, Ghent University, 9000 Ghent, Belgium

Tungsten (W) is envisaged as first wall material for future fusion devices such as DEMO. W-based smart alloys aim at improving one of the drawbacks of W, its fast oxidation in case of accidental reactor scenarios such as a Loss-of-Coolant-Accident (LOCA) with air ingress. By adding chromium (Cr) and yttrium (Y) as alloying elements a protective oxide scale is formed on the smart alloy’s surface when coming into contact with oxygen. During normal plasma operation alloying elements should be depleted, leaving the plasma facing a pure W surface. For assessing the plasma compatibility of smart alloys, WCrY and pure W samples were exposed to steady state pure D plasmas in the linear plasma-device PSI-2. By means of target biasing the ion impact energy was varied. For the two experiments conducted a fluence of 1*10²⁶  ions/m² was reached, further plasma conditions are based on calculated DEMO first wall loads. As a consequence of preferential sputtering, ion energies of 220 eV resulted in a nearly doubled volumetric loss of WCrY in comparison to W. In contrast to this, at lower ion energies of 120 eV, Cr and Y were significantly depleted towards the surface while W was enriched. Analysis by Focussed Ion Beam (FIB) Technique revealed similar erosion yields for W and WCrY.