Details

Autor(en) / Beteiligte

• Olofsson, K E J
• Hanson, J M
• Shiraki, D
• Volpe, F A
• Humphreys, D A
• La Haye, R J
• Lanctot, M J
• Strait, E J
• Welander, A S
• Kolemen, E
• Okabayashi, M

Titel

Array magnetics modal analysis for the DIII-D tokamak based on localized time-series modelling

Ist Teil von

• Plasma physics and controlled fusion, 2014-09, Vol.56 (9), p.95012-15

Ort / Verlag

United States: IOP Publishing

Erscheinungsjahr

2014

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Time-series analysis of magnetics data in tokamaks is typically done using block-based fast Fourier transform methods. This work presents the development and deployment of a new set of algorithms for magnetic probe array analysis. The method is based on an estimation technique known as stochastic subspace identification (SSI). Compared with the standard coherence approach or the direct singular value decomposition approach, the new technique exhibits several beneficial properties. For example, the SSI method does not require that frequencies are orthogonal with respect to the timeframe used in the analysis. Frequencies are obtained directly as parameters of localized time-series models. The parameters are extracted by solving small-scale eigenvalue problems. Applications include maximum-likelihood regularized eigenmode pattern estimation, detection of neoclassical tearing modes, including locked mode precursors, and automatic clustering of modes, and magnetics-pattern characterization of sawtooth pre- and postcursors, edge harmonic oscillations and fishbones.