Advanced Reconstruction of Plasma and Vessel Current Distributions During Disruptions

Capturing the evolution of the plasma during and after disruptions is important for understanding post-disruption plasma stability, heat load evolution, and improving disruption mitigation strategies. Conventional equilibrium tools such as EFIT are limited in their ability to capture the plasma state during highly transient phases, such as disruptions. Filament analysis tools provide a promising alternative for equilibrium modeling in these scenarios. In this work we explore the extension of such models to capture non-axisymmetric eddy currents using the 3D thin-wall E-M code ThinCurr [1] . By including a more complete wall model, eigenmodes or other physically-informed structures, it reduces the number of free parameters and increases the number of constraints by incorporating such 3D sensor information. Of particular interest is whether including a 3D wall model enables improved assessment of 3D structures within the post-disruption plasma from toroidally-distributed magnetic measurements. We will present progress and plans on a comparative analysis between the Thincurr-based approach and JFIT to reconstruct plasma position, shape, and current distributions, including application to disruptive shots in DIII-D, LTX, and SPARC.

[1] A. Battey et al., Nucl. Fusion 64 016010 (2024)