Effect of edge plasma radiation on erosion and damage to iter plasma facing and nearby components

Abstract

Edge plasma behavior plays an essential role in the success of fusion devices by setting the boundary condition for the core plasma. Comprehensive understanding of tokamak edge plasma transport is important for several reasons including plasma stability and heat loads and lifetime of plasma-facing components (PFCs). During normal and disruptive operations in tokamak devices, radiation transport processes play important role in edge plasma dynamic and can be an indirect potential threat to the divertor and nearby components lifetime as well as the direct escaped core plasma impact. The recent upgraded HEIGHTS simulation package1,2 proved the necessity of integrated detail edge plasma transport in the whole SOL area domain. In particular, modeling of impurity contaminations drift with fine details of radiation transport to nearby component surfaces. In coupling with the earlier developed kinetic model of the core plasma escaping3, the radiation transport model was used for simulation of giant ELMs and disruptions in the current design of ITER device. This hybrid approach was enhanced using adaptive mesh refinement for mapping the complex 3D geometry of device walls and implementing nanoscale surface processes. The surfaces response to radiation fluxes from the evolving divertor plasma as a result of intense power deposition has been numerically modeled. Calculations show in agreement with previous studies2 the significant increase in radiation fluxes and damage risk of nearby divertor components during disruptions. From the same plasma core impact energy, the radiation fluxes from the developed divertor plasma increase with the material atomic number. The detailed radiation spectra were calculated and compared for carbon and tungsten as divertor plate materials. Significant damage risk was predicted for the open stainless steel legs of the dome in current ITER design during disruptions from tungsten-made divertor plates.