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Title: Highly time-resolved evaluation technique of instantaneous amplitude and phase difference using analytic signals for multi-channel diagnostics

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.
Authors:
; ; ; ; ; ; ; ; ; ;  [1] ;  [2] ;  [1] ;  [3] ; ; ; ;  [4]
  1. Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)
  2. Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)
  3. (Japan)
  4. Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011 (Japan)
Publication Date:
OSTI Identifier:
22308662
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; EMISSION SPECTROSCOPY; EXPERIMENTAL DATA; HELIOTRON; MAGNETOHYDRODYNAMICS; MULTI-CHANNEL ANALYZERS; PLASMA INSTABILITY; TIME DEPENDENCE; TIME RESOLUTION