Modeling for Control of the Current Profile Evolution During the Ramp-Up Phase at DIII-D
Y. Ou, C. Xu, E. Schuster, T.C. Luce, J.R. Ferron, M.L. Walker, D.A. Humphreys
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Philadelphia, Pennsylvania, October 30-November 3, 2006
Abstract
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Simultaneous real-time control of the current and pressure profiles
can lead to the steady-state sustainment of an internal transport
barrier (ITB). It has also been suggested that global current profile
control, eventually combined with pressure profile control, can be an
effective mechanism for neoclassical tearing mode (NTM) control and
avoidance. A key goal in control of an advanced tokamak (AT) discharge
is to maintain a safety factor (q) and pressure profiles that are
compatible with both MHD stability at high toroidal beta and at a high
fraction of the self-generated bootstrap current. Active feedback
control of the q profile evolution at DIII-D has been already
demonstrated. We report progress towards enabling model-based active
control of the current profile during both plasma current ramp-up and
flattop phases. Initial results on modeling and simulation of the
dynamic evolution of the poloidal flux profile during the ramp-up
phase, open-loop control results, and an assessment of control needs
are presented.