Closed Loop Sawtooth Period Control Using Variable ECCD Injection Angles on Tore Supra

Closed loop control of the sawtooth instability in nuclear fusion

“…Various studies on different tokamaks, like TCV [8], TEXTOR [9] and ASDEX [10], have shown that the period can be altered using a spatially localized Electron Cyclotron Current Drive (ECCD). Recently, some first experimental feedback results with ECCD have been reported on TCV [11] and Tore Supra [12]. However, these results do not provide a basis for structured controller design, which requires a control-oriented model of the sawtooth behavior.…”

Recent Advances in Sawtooth Control

“…In section VII recent JET experiments are described briefly which aim to verify the control mechanism, and minimise the effect of ICRH on the current profile. Without such experiments, it could be argued that sawtooth control occurred because of a magnetic shear change, as in ECCD experiments of TCV [30,18] and TORE-SUPRA [31,19]. Finally, it should be pointed out that despite the apparent applicability of asymmetric NBI and RF distributions to control sawteeth in ITER, there is a downside.…”

Sawtooth control using electron cyclotron current drive in ITER demonstration plasmas in DIII-D

“…Consequently, recent experiments have focussed on destabilizing sawteeth using ECCD in the presence of energetic particles. Sawtooth destabilization of long period sawteeth induced by ICRH generated core fast ions with energies 0.5 MeV was achieved in Tore Supra, even with modest levels of ECCD power [30,31]. Similarly, ECCD destabilization has also been achieved in the presence of ICRH accelerated NBI ions in ASDEX Upgrade [32] as well as with normal NBI fast ions in ASDEX Upgrade [7] and JT-60U [33].…”