Transient multiphysics modeling of the electromagnetic loads on the first wall during plasma disruptions

Abstract

A transient three-dimensional multiphysics finite element model that relies on coupling electromagnetic and solid-mechanics modules was developed for modeling the effect of electromagnetic (EM) loads on the in-vessel components during plasma midplane disruptions. The T-Ω formulation is employed within the finite element framework to numerically solve the Maxwell's governing equations of the electromagnetic problem, for the induced current density ($J$), and magnetic flux density ($B$) on the in-vessel components. The $J\times B$ forces are fed into the transient large strain kinematics within solid mechanics module through a one-way coupled interface for computation of stress and displacement distributions on the first wall (FW). The effects of the continuity of the FW on $J\times B$ forces and consequently stress state are studied. The current densities are higher at the edges of the non-continuous FW and at the midplane of the continuous FW. The current quench produces forces that both pull away and push the non-continuous FW to the plasma while the current quench causes the continuous FW to be pushed towards the plasma only. The maximum stress on the non-continuous FW and the continuous FW are 93 MPa and 52 MPa. The factor of safety (FOS) calculated for non-continuous and continuous FWs under the EM loads are about 5 and 10 respectively. Both walls will withstand the EM loads without failure, but the continuous blanket FW has higher structural integrity for the EM loads. Preliminary studies of the EM loads on the inboard blanket are consistent with the FW results and earlier works.