Abstract Details
Abstracts
Author: Joseph R Jepson
Requested Type: Poster
Submitted: 2025-03-14 21:59:08
Co-authors: S. A. Sabbagh, E. C. Howell, G. Bustos-Ramirez, H. Lee, J. D. Riquezes, F. C. Sheehan, G. Tillinghast, M. Tobin, V. Zamkovska
Contact Info:
Columbia University
100 Stellerator Rd
Princeton, NJ 08540
United States
Abstract Text:
As the fusion community prepares for the next generation of high-performance tokamaks, disruption prediction and avoidance remains of paramount importance. Unmitigated disruptions in higher-performance devices such as ITER are anticipated to produce unacceptable forces on the device and unacceptable heat loads on the plasma facing components. Effective disruption avoidance and mitigation relies crucially on an ability to predict, in real-time, the plasma state, and as necessary, to activate appropriate actuators to keep the plasma away from disruption boundaries in parameter space. The Disruption Event Characterization and Forecasting (DECAF) code [1] automates the identification of the chain of events leading to a disruption and provides appropriate forecasting of such events, allowing appropriate plasma control systems to be activated to prevent (or mitigate) plasma disruptions. Recent work on the KSTAR tokamak demonstrated the first disruption avoidance triggered by the real-time DECAF system [2]. In support of DECAF, recent NIMROD simulations have been performed for MAST-U shot 49220. These simulations show that the safety factor dipping below one leads to the creation of magnetic islands extending between the two q=1 surfaces, which results in a redistribution of angular momentum in the plasma. A hypothesis is that this resistive mode couples to eddy currents in the wall, resulting in a slowing down of the plasma rotation leading to mode locking. While a conducting wall was used for these simulations, results with a resistive wall are forthcoming. Future simulations will further investigate the causes of mode growth and loss of high beta in MAST-U plasmas. The interplay of rotation, shaping, and q shear on plasma stability and mode dynamics will be examined.[1] S. A. Sabbagh et al., Phys. Plasmas 30, 032506 (2023). [2] https://www.apam.columbia.edu/first-demonstration-tokamak-disruption-avoidance-disruption-event-characterization-and-forecasting-0
Characterization: 1.0
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