Progress in disruption prevention for ITER
T. Strait, (E. Schuster) et al. (Collaboration Paper)
Nuclear Fusion 59 (2019) 112012 (12pp)
Abstract
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Key plasma physics and real-time control elements needed for robustly
stable operation of high fusion power discharges in ITER have been
demonstrated in recent research worldwide. Recent analysis has
identified the current density profile as the main drive for disruptive
instabilities in discharges simulating ITER’s baseline scenario with
high and low external torque. Ongoing development of model-based
profile control and active control of magnetohydrodynamic instabilities
is improving the stability of multiple scenarios. Significant advances
have been made toward real-time physics-based prediction of instabilities,
including path-oriented analysis, active sensing, and machine learning
techniques for prediction that are beginning to go beyond simple disruption
mitigation trigger applications. Active intervention contributes to
prevention of disruptions, including forced rotation of magnetic islands
to prevent wall locking, and localized heating/current drive to shrink
the islands. Stable discharge rampdowns have been achieved with the
fastest ITER-like scaled current ramp rates, while maintaining an X-point
configuration. These elements are being integrated into stable operating
scenarios and new event-handling systems for off-normal events in order
to develop the physics basis and techniques for robust control in ITER.