Effect of ELMS and disruptions on FNSF plasma-facing components

Abstract Previous work has addressed the thermomechanical and electromagnetic effects of ELMs and disruptions on plasma-facing components in conceptual, commercial fusion reactors. Given that the proposed Fusion Nuclear Science Facility (FNSF) will have different geometry and plasma parameters, it is necessary to address similar issues in that context. Hence, this paper presents two key results: the thermomechanical response of the first wall and divertor to expected FNSF ELMs and disruptions, and the electromagnetic response of all structures inside the FNSF vacuum vessel to a plasma current quench. Structures considered in the electromagnetic analyses include the vacuum vessel, blankets, structural ring (which supports many of the internal components), and all internal shells used for plasma stability and control. The first wall is a ferritic steel structure with a thin tungsten coating and the divertor is all tungsten. Properties used for the divertor are those of pure tungsten, though it is quite possible that some alloy or nanostructured material would be employed at some point. Both the first wall and divertor are gas-cooled, so coolant pressures are quite high (8–10 MPa). The finite element code ANSYS is used to carry out all analyses and parametric studies are employed in order to identify parameters for which uncertainties will have a significant effect on the predicted performance. The ELM and disruption loads are found to be substantially smaller than those expected in a commercial reactor, so the component designs have more margin.