Closed-loop Control of the Safety Factor Profile in the TCV Tokamak
J. Barton, E. Schuster, F. Felici and O. Sauter
53rd IEEE Conference on Decision and Control
Los Angeles, California, USA, December 15-17, 2014
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Abstract
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A key property that has a close relationship to both the performance
and stability of the plasma in nuclear fusion tokamak devices is the
safety factor profile (q-profile). As a result, extensive research has
been conducted to develop algorithms to actively control the evolution
of the q-profile with the goal of optimizing the tokamak approach to
nuclear fusion energy production. The actuators that can be utilized
to control the q-profile are the total plasma current, the auxiliary
heating/current-drive system and the line-average electron density.
In this work, we first investigate the effect that the control input
direction associated with pure plasma heating has on the q-profile in
low performance (L-mode) operating scenarios in the TCV tokamak.
Secondly, we design feedback controllers that utilize the total plasma
current and exclusively the current-drive capabilities of the
auxiliary sources to control the q-profile in L-mode scenarios in TCV.
The controllers are designed to put emphasis on achieving the target
q-profile in different spatial regions as well as to respond
differently to errors in the q-profile. The control performance of
each controller is tested with the simplified physics-based plasma
profile simulation code RAPTOR. The comparison of the closed- loop
performance of these controllers is done in preparation for future
q-profile control experiments in the TCV tokamak.
