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Current profile and energy control in DIII-D plasmas using discrete-time variable-structure control

Authors :
Christopher Holcomb
David Humphreys
M Menno Lauret
Michael L. Walker
Eugenio Schuster
J.R. Ferron
B.G. Penaflor
William Wehner
Robert D. Johnson
T.C. Luce
Source :
MED
Publication Year :
2017
Publisher :
IEEE, 2017.

Abstract

One of the most promising candidates to produce clean nuclear fusion energy is the tokamak, a device magnetically confining an extremely hot plasma (i.e. an ionized gas) where the fusion reactions take place. To produce nuclear fusion energy using tokamak devices, it is crucial that the poloidal magnetic flux (characterized by the so-called q profile) and the plasma internal energy are tightly controlled to avoid magnetohydrodynamic instabilities and to reach the high pressures and temperatures that are needed for high fusion-power density. Simultaneous control of the q profile and the internal energy is challenging for a number of reasons: the system is nonlinear, there are significant parameter uncertainties and large disturbances, the available number of actuators is small, and the actuation authority is limited from a control perspective. Therefore, a variable-structure controller is proposed in this work to tackle this plasma control problem since this type of controllers can typically diminish the impact of serious disturbances and nonlinearities while still leading to good performance. Simulations and recent experiments on the DIII-D tokamak in a challenging high-confinement (H-mode) plasma regime show that this control approach does indeed lead to good and repeatable control of the q profile and the internal energy.

Details

Database :
OpenAIRE
Journal :
2017 25th Mediterranean Conference on Control and Automation (MED)
Accession number :
edsair.doi...........0bb13fcc53f5f30dfa8b51c282c56f25