Development of a Computational Model for MHD Response of a Novel Vacuum Vessel to Disruption Events Using the MFEM Library*

A computational model using the finite element library MFEM to predict the response of a novel multiphase vacuum vessel technology to disruption events is presented. A vacuum vessel design consisting of a thin plasma facing wall of silicon carbide (SiC), molten salt cooling channels, a thick layer of SiC, and helical liquid lead channels to mitigate structural stresses during disruptions is studied. This configuration potentially reduces the structural stresses in a tokamak during disruption events by forcing induced currents to travel largely parallel to the toroidal magnetic field through the lead, reducing the magnetic force and converting shear stress to fluid flows and pressure gradients in the lead. The optimization of such a vacuum vessel to minimize the peak structural loading during disruptions requires exploration of a large geometric space, for which most configurations are prohibitive to solve analytically. To this end, a model using the finite element method is designed and first validated against simple geometries for which analytic solutions are known, and then applied to search for favorable vacuum vessel designs.