Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

• development and benchmarking of 2-d and 3-d models for disruption dynamics,
including electromagnetic and thermal loads, runaway electrons, wall interaction, etc.
• Theoretical and numerical stability modeling, including time-dependent scenario
modeling, to improve capabilities for disruption prediction.
• development and benchmarking of real-time energy balance and transport analysis, for
early warning of impurity accumulation and other possible disruption precursors.
• development of real-time stability calculations, to warn of proximity to stability limits.
• development of direct, real-time determination of plasma stability through “active mhd
spectroscopy” (mhd damping rate measurement by exciting the mode at low amplitude).
• development of diagnostics and real-time analysis for identification of a growing
instability at amplitude well below the threshold for disruption.
• development and testing in present devices of sensors that can provide the required
measurements for disruption prediction in a long-pulse, nuclear environment.
avoidance of disruptions
disruption avoidance includes both passive and active techniques to avoid instabilities. The rapid
growth rate of many ideal mhd instabilities means that their stability limits must be detected
and avoided well ahead of the onset. on the other hand, normal operation may lie beyond passive
stability limits such as those for the neoclassical tearing mode or the resistive wall kink mode;
these cases require active stabilization of the plasma. The disruption predictors described in the
preceding list form the input to these passive and active controls.
key research steps include:
• modeling and experimental benchmarking of control strategies to steer the operating
point away from an impending instability, without approaching other operating limits.
• modeling and experimental benchmarking of control strategies to recover normal
operation in the event of an instability or another potential disruption-inducing event.
• modeling and experimental benchmarking of strategies for recovery of normal operation
in the event of an off-normal condition caused by component failure or human error, and
specification of operating practices that minimize such events.
• development of actuators capable of modifying the pressure, current density, and rotation
profile with minimal auxiliary power, and suitable for use in a nuclear environment.
• modeling and experimental benchmarking of active stability control using actuators such
as localized current drive and non-axisymmetric coils.
• development of high-bandwidth coils for mhd spectroscopy and active feedback control,
suitable for use in a nuclear environment.
• assessment of the impact of implementing disruption prediction and avoidance
techniques, consistent with iteR and demo requirements on fusion power production.
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