Real-time wavelet detection of crashes in limit cycles of non-stationary fusion plasmas

TitleReal-time wavelet detection of crashes in limit cycles of non-stationary fusion plasmas
Publication TypeJournal Article
Year of Publication2011
AuthorsM. van Berkel, G. Witvoet, MR de Baar, P Nuij, H.G ter Morschec, M. Steinbuch
JournalFusion Engineering and Design
Volume86
Issue12
Pagination2908-2919
Date PublishedDec
Type of ArticleArticle
ISBN Number0920-3796
KeywordsASDEX UPGRADE, CONFINEMENT, EDGE, Edge-detection, Filter-bank, FLUCTUATIONS, FREQUENCY ANALYSIS, INTERMITTENCY, Localized Mode (ELM), MODES, Real-time, REFLECTOMETRY, Sawtooth, SAWTOOTH PERIOD, SIGNALS, TOKAMAK, Wavelet
Abstract

The high performance mode (H-mode) is one of the baseline plasma scenarios for the experimental fusion reactor ITER. This scenario features a periodic crash-like reorganization of the plasma pressure and the magnetic flux in the plasma core and plasma periphery. The core instability is often referred to as the sawtooth instability while the instability at the edge of the plasma is referred to as ELM. In this paper we present an algorithm for optimized (low latency, robust and high fidelity) real-time sensing of the crashes. The algorithm is based on time-scale wavelet theory and edge-detection. It is argued that detection of crashes has considerably less delay than the other methods. The realized accuracy of the detection algorithm is well below the uncertainty of the crash period for most crashes. Multiresolution analysis enables distinction between different sizes of sawtooth crashes due to the different sizes of wavelets (scales), resulting in an algorithm, which is robust and accurate. Although strictly speaking, the crash detection method is demonstrated for sawteeth measured with ECE only, it can be applied to any periodic crash, measured with any temporally resolved data. Note that the possibility of differentiating between crash like events of different nature depends on their individual time-scales and used measurement setup. (C) 2011 Elsevier B.V. All rights reserved.

DOI10.1016/j.fusengdes.2011.07.002
Division

FP

Department

TP

PID

9b690e4fb3033a368ba88f376ceeaff9

Alternate TitleFusion Eng. Des.

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