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

Abstract

Here, 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.

Authors:
 [1];  [1];  [1];  [1];  [2];  [2];  [2];  [2];  [2];  [3];  [3]
  1. Columbia Univ., New York, NY (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1356334
Grant/Contract Number:
FC02-04ER54698
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 56; Journal Issue: 9; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; inference methods; magnetohydrodynamics; microinstabilities

Citation Formats

Olofsson, K. Erik J., Hanson, Jeremy M., Shiraki, Daisuke, Volpe, Francesco A., Humphreys, David A., La Haye, Robert J., Lanctot, Matthew J., Strait, Edward J., Welander, Anders S., Kolemen, Egemen, and Okabayashi, Michio. Array magnetics modal analysis for the DIII-D tokamak based on localized time-series modelling. United States: N. p., 2014. Web. doi:10.1088/0741-3335/56/9/095012.
Olofsson, K. Erik J., Hanson, Jeremy M., Shiraki, Daisuke, Volpe, Francesco A., Humphreys, David A., La Haye, Robert J., Lanctot, Matthew J., Strait, Edward J., Welander, Anders S., Kolemen, Egemen, & Okabayashi, Michio. Array magnetics modal analysis for the DIII-D tokamak based on localized time-series modelling. United States. doi:10.1088/0741-3335/56/9/095012.
Olofsson, K. Erik J., Hanson, Jeremy M., Shiraki, Daisuke, Volpe, Francesco A., Humphreys, David A., La Haye, Robert J., Lanctot, Matthew J., Strait, Edward J., Welander, Anders S., Kolemen, Egemen, and Okabayashi, Michio. Mon . "Array magnetics modal analysis for the DIII-D tokamak based on localized time-series modelling". United States. doi:10.1088/0741-3335/56/9/095012. https://www.osti.gov/servlets/purl/1356334.
@article{osti_1356334,
title = {Array magnetics modal analysis for the DIII-D tokamak based on localized time-series modelling},
author = {Olofsson, K. Erik J. and Hanson, Jeremy M. and Shiraki, Daisuke and Volpe, Francesco A. and Humphreys, David A. and La Haye, Robert J. and Lanctot, Matthew J. and Strait, Edward J. and Welander, Anders S. and Kolemen, Egemen and Okabayashi, Michio},
abstractNote = {Here, 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.},
doi = {10.1088/0741-3335/56/9/095012},
journal = {Plasma Physics and Controlled Fusion},
number = 9,
volume = 56,
place = {United States},
year = {Mon Jul 14 00:00:00 EDT 2014},
month = {Mon Jul 14 00:00:00 EDT 2014}
}

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Cited by: 6works
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