Towards a Mean‐Field Braginskii Model for Stellarators

Experiments in the stellarator Wendelstein 7‐X indicate that particle drifts have a significant impact on the plasma in the scrape‐off layer. However, drift effects have been absent in the mean‐field transport codes such as EMC3‐Eirene. For this reason, we present the first steps towards a mean‐field model that incorporates drifts. The code is based on the BOUT++ framework and includes an EMC3‐Eirene‐like transport model that yields steady‐state plasma profiles. To investigate the potential distribution on these profiles, we include a 3‐field model that evolves the electrostatic potential and verifies the implementations via the method of manufactured solutions. As a first application, we carry out simulations of the scrape‐off layer of Wendelstein 7‐X. The inferred potential distribution is predominantly aligned with the separatrix.