Time-series analysis of nonstationary plasma fluctuations using wavelet transforms

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1147715· OSTI ID:451910

Santoso, S; Powers, E J; Bengtson, R D; Ouroua, A ^[1]

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1. Fusion Research Center, The University of Texas at Austin, Austin, Texas 78712-1084 (United States)

A wavelet or time-scale approach to analyzing a single time series and two time series, in which the fluctuating quantities are statistically nonstationary, is presented. The time scale and scale {open_quotes}power spectra{close_quotes} are introduced and utilized to analyze transient potential fluctuations measured at the core of sawtoothing TEXT-U plasmas. The results show features that have not been previously observed using any Fourier techniques. In addition, the linear time-scale {open_quotes}coherence spectrum{close_quotes} is developed to quantify the degree of linear relationship between two nonstationary fluctuating quantities in the time-scale domain. Such a spectrum is also useful in tracking the time-varying phase difference. A numerical example is provided to demonstrate the efficacy of the time-scale spectra. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 451910
• Report Number(s): CONF-960543--
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 1 Vol. 68; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALGORITHMS
FLUCTUATIONS
PLASMA DIAGNOSTICS
PLASMA POTENTIAL
SAWTOOTH OSCILLATIONS
SPECTRAL DENSITY
TEXT DEVICES
TIME-SERIES ANALYSIS
TOKAMAK DEVICES
plasma fluctuations
plasma probes
sawtooth instability
spectral analysis
time series
wavelet transforms