1. Electromechanical modelling and design for phase control of locked modes in the DIII-D tokamak.
- Author
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K E J Olofsson, W Choi, D A Humphreys, R J La Haye, D Shiraki, R Sweeney, F A Volpe, and A S Welander
- Subjects
ELECTROMECHANICAL devices ,TOKAMAKS ,QUANTUM perturbations ,HEAT conduction ,HEAT transfer - Abstract
A basic nonlinear electromechanical model is developed for the interaction between a pre-existing near-saturated tearing-mode, a conducting wall, active coils internal to the wall, and active coils external to the wall. The tearing-mode is represented by a perturbed helical surface current and its island has a small but finite moment of inertia. The model is shown to have several properties that are qualitatively consistent with the experimental observations of mode-wall and mode-coil interactions. The main purpose of the model is to guide the design of a phase control system for locked modes (LMs) in tokamaks. Such a phase controller may become an important component in integrated disruption avoidance systems. A realistic feedback controller for the LM phase is designed and tested for the electromechanical model. The results indicate that a simple fixed-gain controller can perform phase control of LMs with a range of sizes, and at arbitrary misalignment relative to a realistically dimensioned background error field. The basic model is expected to be a useful minimal dynamical system representation also for other aspects of mode-wall-coil interactions. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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