Stabilization of NTMs using real-time equilibrium reconstruction on TCV

In tokamak plasmas, Neoclassical Tearing Modes (NTMs) can limit $\beta $ values to below the ideal MHD limit and degrade plasma confinement [1]. Therefore, to reach the high performance tokamak regime, control and stabilization of NTMs is essential; it can be achieved using localized electron cyclotron heating and current drive (ECH/ECCD) [2]. In previous TCV experiments, NTM stabilization was obtained as ECH/ECCD deposition was swept in one direction until the mode disappeared [3]. We now enhance our control of NTMs using a real-time (RT) version of the equilibrium code LIUQE [4]. RT-LIUQE gives the safety factor (q) profile, and from pre-calculated ray-tracing and an assumption of the mode rational surface, a target q is converted to a requested EC launcher angle. When an NTM appears, one, or several, EC beams are directed at the NTM and the mode is successfully stabilized. \textit{This work was supported in part by the Swiss National Science Foundation.} \\[4pt] [1] Sauter O. \textit{et al} 1997 \textit{Phys. Plasmas} \textbf{4} 1654\\[0pt] [2] La Haye R.J. 2006 \textit{Phys. Plasmas} \textbf{13 }055501\\[0pt] [3] Felici F. \textit{et al }2012 \textit{Nucl. Fusion} \textbf{52} 074001\\[0pt] [4] Hofmann F. \textit{et al }1988 \textit{Nucl. Fusion} \textbf{28} 1871