Dependence of disruption forces on the plasma position inside the vacuum vessel in tokamaks

Abstract

The earlier analytical model (Pustovitov and Kiramov 2018 Plasma Phys. Controlled Fusion 60, 045011) for plasma-wall electromagnetic interaction in tokamaks is revised and extended. In that model, the magnetic field B was treated as tangential to the vacuum vessel (VV) wall, which implied some pre-selected plasma position inside the VV. Here, in contrast, the plasma shift with respect to VV is a free parameter, and the wall is not a magnetic surface. The derived expressions explicitly show the effect of , or the normal component of B on the poloidal distribution of the disruption force on the wall, while the integral radial force is found to be insensitive to . Similar results have been obtained recently in CarMa0NL simulations (Isernia et al 2019 Plasma Phys. Control. Fusion 61 115003), which are now explained and confirmed analytically, including the role and interplay of the normal and tangential forces as functions of . The standard large-aspect-ratio model of an axisymmetric tokamak with circular plasma and an almost coaxial wall is used. Additionally, to facilitate comparison with previous studies, the ideal-wall reaction is assumed.