SOLPS ITER and ERO2.0 modelling to estimate the influence of eroded impurities from wall and samples on experimental results in GyM

Investigating helium (He) plasma and its interaction with plasma-facing materials is one of the key requirements in light of ITER pre-fusion operation phase. Experimental campaigns devoted to plasma-wall interaction studies with He plasma have been recently performed in WEST, JET-ILW and AUG tokamaks in support of the preparation of ITER operation. In addition, experiments performed in linear plasma devices (LPDs) can already reproduce some of the relevant exposure conditions expected in ITER, e.g. in terms of ion fluxes and fluences, and are routinely used to investigate He-induced materials modifications. In this framework, numerical simulations provide an essential tool for the interpretation of LPD experiments extracting information on plasma dynamics and composition, erosion and surface evolution, impurity migration and redeposition. This contribution investigates these aspects considering a He plasma experiment in the GyM linear plasma device [1] modelled through the coupling of SOLPS-ITER [2] and ERO2.0 [3] codes. Recent work presented the coupling strategy of the two codes and applied them to study the erosion of internal walls in GyM due to He plasma, as a function of the wall material and of the bias voltage [4]. The results presented aim to evaluate the effect of impurities sputtered from the stainless-steel wall and from the sample-holder molybdenum mask onto the tungsten exposed samples. The He fluxes on the wall and on the sample-holder (approximately 1020 He m-2 s-1) are retrieved from SOLPS-ITER simulations and benchmarked against Langmuir probes experimental measurements. The sample-holder geometry is drawn with a Computer Aided Design (CAD) tool and imported into ERO2.0 simulation volume. The SOLPS-ITER plasma background is then exploited for ERO2.0 erosion and migration studies. In particular, the contribution of wall impurities on sample erosion is estimated, identifying the main wall components which influence experimental measurements. In addition, the influence of impurities eroded from the sample-holder structures on sample erosion is investigated. Finally, the migration of particles sputtered from the samples in the GyM volume and their redeposition locations are presented.