Central Safety Factor Control in DIII-D using Neutral Beam Injection and Electron Cyclotron Launchers in Zero Input-Torque Scenarios
A. Pajares and E. Schuster
Proceedings of the 2017 IEEE Conference on Control Technology and Applications (CCTA)
Kohala Coast, Hawaii, USA, August 27-30, 2017
Abstract
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The tokamak is a torus-shaped machine whose final purpose is generating
energy from nuclear fusion reactions. In order to achieve this goal, a
reactant plasma is confined inside the tokamak by means of magnetic
fields. For a tokamak to be commercially competitive, operation for
long periods of time at high-performance operating points will be needed.
Those high-performance scenarios are characterized by a steady-state,
stable plasma operation in which the safety factor, a property of the
plasma that measures the pitch of the magnetic field lines, plays a
decisive role. In particular, control of the central safety factor,
which is the value of the safety factor at the tokamak magnetic axis,
is one of the crucial aspects to the success of tokamak devices due to
its close relationship to magneto- hydrodynamic stability. Therefore,
control algorithms for the central safety factor in tokamaks will be
required. In the present work, a linear controller is proposed for the
regulation of the central safety factor using neutral beam injection
and electron cyclotron launchers. This controller is designed to
guarantee a zero input torque delivered by the neutral beam injection
system. The controller performance is tested via a simulation study in
a DIII-D scenario.