Implementation of MHD-mode induced disruption forecaster into the DECAF code *

Timely detection and prevention of plasma disruptions, leading to abrupt losses of the plasma confinement, is a prerequisite for successful operation of next-step tokamaks such as ITER. The Disruption Event Characterization and Forecasting (DECAF) code [1] implements algorithms that aim at resolving, characterizing and forecasting the chain of events that precede the disruption. One such event is onset of an MHD mode that triggers the plasma deconfinement once it reaches a critical amplitude. This amplitude, for modes that are static in the laboratory frame, has been estimated in past work with an empirical formula [2] that was recently validated on multiple devices [3]. Application of this formula thus represents a potentially important ingredient for a forecaster of the disruption onset. The formula’s accuracy will be explored and the underlying physics analyzed using DECAF on a large set of plasmas from several tokamak devices including KSTAR and NSTX. This analysis will serve as an important base for further expansion of offline and real-time DECAF capabilities.

[1] S.A. Sabbagh et al. Proc.27th IAEA Fusion Energy Conference, Ahmedabad, India (2018)

[2] P.C. de Vries et al., Nuclear Fusion 56 (2015) 026007

[3] V. Klevarova et al., Fusion Engineering and Design 160 (2020) 111945