episciences.org_14641_2026051822193364920260518221933649episciences.orgraphael.tournoy+crossrefapi@ccsd.cnrs.frepisciences.orgOpen Plasma Science3076-146810.46298/journals/opshttp://ops.episciences.org02242025Volume 1E.FableMax-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germanyhttps://orcid.org/0000-0001-5019-9685G.TardiniMax-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germanyhttps://orcid.org/0009-0002-0544-6880L.GiannoneMax-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germanyhttps://orcid.org/0000-0001-5611-200Xthe ASDEX UpgradeTeamA new axisymmetric equilibrium solver has been written, called FEQIS (Flexible EQuIlibrium Solver), which purpose is to be used inside integrated modeling of tokamak plasmas. The FEQIS code solves the Grad-Shafranov equation and the "circuit" equations for the external coils and passive conducting structures that are toroidally connected. The code has been specifically equipped with flexibility in choice of circuit connections, and a stripped-down numerical scheme for the solution of the Grad-Shafranov equation through a structure of multi-level simplifications which can be tested against the required accuracy.022420250127202514641https://creativecommons.org/licenses/by-nc-nd/4.0https://creativecommons.org/licenses/by-nc-nd/4.0https://creativecommons.org/licenses/by-nc-nd/4.0arXiv:2410.1363010.48550/arXiv.2410.13630https://arxiv.org/abs/2410.13630v4https://arxiv.org/abs/2410.13630v210.46298/ops.14641http://ops.episciences.org/14641https://arxiv.org/pdf/2410.13630v7https://arxiv.org/pdf/2410.13630v7