Global SOLPS-ITER and ERO2.0 coupling in linear devices: study plasma-wall interaction in helium plasma

Helium (He) plasma is foreseen to characterize the Pre-Fusion Power Operation phase (PFPO) in ITER. Due to its peculiar effects on plasma-facing materials with respect to hydrogenic plasmas, plasma-wall interaction (PWI) in He must be carefully investigated. Since, currently, there are no tokamaks comparable to ITER, the use of linear plasma devices (LPDs) to reproduce some of the relevant features of ITER He plasma is fundamental. At the same time, it is of extreme interest to develop numerical tools that can effectively help to interpret the observed results in LPDs. Two state-of-the-art codes for the edge plasma description and plasma-wall interaction are SOLPS-ITER and ERO2.0, respectively, and their coupling would pave the way to a full simulation of the experiments carried out in LPDs. Recently SOLPS-ITER code has been already used in linear geometry to simulate non-hydrogenic plasmas, including helium [1]. On the contrary, ERO2.0 has been used in linear machines but never in connection with a background plasma code [2,3]. In the present work, the first global coupling between SOLPS-ITER and ERO2.0 related to the linear machine GyM is shown. The background plasma previously obtained with SOLPS-ITER is exploited with the aim of performing ERO2.0 global simulation to study the erosion of GyM internal walls. The issues related to the transition from the SOLPS-ITER 2D background plasma to the ERO2.0 3D one in a linear device are investigated. First simulations considering a full iron wall are performed, and the role of different wall materials (carbon, copper, tungsten) is addressed. The effects of the inclusion of a bias voltage on erosion and impurity migration is also studied. Eroded particles migration is shown to be influenced by the ionization potential of materials, determining different locations, energy and angle distributions of redepositing particles.