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Title: Highly time-resolved evaluation technique of instantaneous amplitude and phase difference using analytic signals for multi-channel diagnosticsa)
Authors: Ohshima, S.
Kobayashi, S.
Yamamoto, S.
Nagasaki, K.
Mizuuchi, T.
Kado, S.
Okada, H.
Minami, T.
Lee, H. Y.
Zang, L.
Kenmochi, N.
Kasajima, K.
Ohtani, Y.
Shi, N.
Nagae, Y.
Konoshima, S.
Sano, F.
Author's alias: 大島, 慎介
Issue Date: Nov-2014
Publisher: AIP Publishing
Journal title: Review of Scientific Instruments
Volume: 85
Issue: 11
Thesis number: 11E814
Abstract: A fluctuation analysis technique using analytic signals is proposed. Analytic signals are suitable to characterize a single mode with time-dependent amplitude and frequency, such as an MHD mode observed in fusion plasmas since the technique can evaluate amplitude and frequency at a specific moment without limitations of temporal and frequency resolutions, which is problematic in Fourier-based analyses. Moreover, a concept of instantaneous phase difference is newly introduced, and error of the evaluated phase difference and its error reduction techniques using conditional/ensemble averaging are discussed. These techniques are applied to experimental data of the beam emission spectroscopic measurement in the Heliotron J device, which demonstrates that the technique can describe nonlinear evolution of MHD instabilities. This technique is widely applicable to other diagnostics having necessity to evaluate phase difference.
Rights: © 2014 AIP Publishing LLC
DOI(Published Version): 10.1063/1.4891102
Appears in Collections:Journal Articles

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