Progress in Disruption Prevention for ITER
T. Strait, (E. Schuster), et al. (Collaboration Paper)
27th IAEA Fusion Energy Conference
Gandhinagar, India, October 22-27, 2018
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 MHD 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 a new event-handling system for
off-normal events in order to develop the physics basis and techniques
for robust control in ITER.