Title
Magnetic island localization for NTM control by ECE viewed along the same optical path of the ECCD beam
Author
Bongers, W.A.
Goede, A.P.H.
Westerhof, E.
Oosterbeek, J.W.
Doelman, N.J.
Schüller, F.C.
de Baar, M.R.
Kasparek, W.
Wubie, W.
Wagner, D.
Stober, J.
Team, T.
TNO Industrie en Techniek
Publication year
2009
Abstract
Neoclassical tearing modes (NTMs) deteriorate highpressure tokamak plasma confinement and can be suppressed by electron cyclotron current drive (ECCD). In order to obtain efficient suppression, the ECCD power needs to be deposited at the center of an NTM magnetic island. To enhance efficiency, this power also needs to be synchronized in phase with the rotation of the island. The problem is that of real-time detection and precise localization of the island(s) in order to provide the feedback signal required to control the ECCD power deposition area with an accuracy of 1 to 2 cm. Existing schemes based on mode location, equilibrium reconstruction, and plasma profile measurements are limited in positional and temporal accuracy and moreover will become very complex when applied to ITER. To overcome these limitations, it is proposed to provide the feedback signal from electron cyclotron emission (ECE) measurements taken along the identical line of sight as traced by the incident ECCD millimeter-wave beam but in reverse direction. Experiments on TEXTOR have demonstrated a proof of principle. These measurements motivate the further development and the implementation of such an ECCD-aligned ECE system for NTM control in larger fusion machines. Possible implementation of such a system on ASDEX-Upgrade, based on waveguides equipped with a fast directional switch, is presented in this paper. Possible further development for ITER is also discussed.
Subject
ECHR/ECCD
NTM stabilization
Electron cyclotron resonance
Experimental reactors
Fusion reactors
Plasma confinement
Tokamak devices
Asdex upgrades
Electron cyclotron current drives
Electron-cyclotron emissions
Equilibrium reconstruction
Feedback signals
Fusion machines
Magnetic islands
Millimeter-wave beams
Neo-classical tearing modes
NTM stabilization
Optical paths
Plasma profiles
Power depositions
Real-time detections
To reference this document use:
http://resolver.tudelft.nl/uuid:86a12750-28fb-49a1-a336-3eeadbaaac79
TNO identifier
241383
ISSN
1536-1055
Source
Fusion Science and Technology, 55 (2), 188-203
Document type
article