Filament Reconstructions of Plasma and 3D Vessel Current Distributions During Disruptions

Capturing the evolution of the plasma shape and position during disruptions is important for understanding heat load evolution, and improving disruption mitigation strategies. Conventional equilibrium reconstruction tools such as EFIT have limited capability to resolve the fast-evolving plasma parameters during disruptions and typically neglect the effects of currents induced in surrounding conducting structures. Filament analysis tools provide a promising alternative for modeling in these scenarios, but have been limited in capturing conducting wall induced currents with sufficient fidelity. In this work, we explore the extension of such models to capture non-axisymmetric eddy currents using the 3D thin-wall code ThinCurr [1]. Of particular interest is whether including the 3D wall eddy currents enables improved modeling of the plasma evolution from magnetic sensor measurements. We will present comparative analysis between the Thincurr-based approach and JFIT [2] to reconstruct plasma position, shape, and current distributions, including application to disruptive shots in DIII-D, SPARC, and HBT-EP.

[1] Christopher Hansen, et al. (2024). ThinCurr: An open-source 3D thin-wall eddy current modeling code for the analysis of large-scale systems of conducting structures.

[2] Humphreys, D. A., & Kellman, A. G. (1999). Analytic modeling of axisymmetric disruption halo currents. Physics of Plasmas, 6(7), 2742–2756.