Correlation of electron temperature collapses evolution, mode activity and disruptions in KSTAR through DECAF analysis*

Due to its relevance for the economic viability of fusion power plants, early detection of disruption precursors along with strategies for control and mitigation have been identified as key goals on the next KSTAR experimental campaign scheduled to start later this year. This work presents early forecasting of some plasma disruptions through detection of rapid changes in the magnetic topology, which are observed as local (and global) electron temperature collapses due to the fast thermal transport that follows the opening of the field lines. A general framework to identify and categorize electron temperature collapses is outlined and its application to KSTAR experiments using the electron cyclotron emission diagnostic (ECE) data is presented. Correct characterization of the type of thermal collapse and its relation to key physics events allows for an accurate assessment of the plasma state and up to ~1s disruption warnings in KSTAR, offering the opportunity to trigger disruption avoidance schemes. At the same time, monitoring the plasma state leading to a thermal collapse opens an avenue to trigger actuators to keep the plasma within a stable domain. The formalism presented in this work has been implemented in the DECAF code [1], allowing the analysis of a wide range of KSTAR shots. Work is currently is underway to apply the concepts presented here in real time DECAF analysis modules to be run during the coming KSTAR experimental campaign to examine its use in real-time disruption prediction.

 

[1] S.A. Sabbagh, et al., Phys. Plasmas 30, 032506 (2023); https://doi.org/10.1063/5.0133825