title: Highly time-resolved evaluation technique of instantaneous amplitude and phase difference using analytic signals for multi-channel diagnostics.
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.
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ohshima
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nagasaki
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Mizuuchi
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kado
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Okada
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Minami
authors.affiliation: Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea.
authors.forename: H Y
authors.initials: HY
authors.lastname: Lee
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: L
authors.initials: L
authors.lastname: Zang
authors.affiliation: Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kenmochi
authors.affiliation: Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kasajima
authors.affiliation: Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ohtani
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Shi
authors.affiliation: Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nagae
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Konoshima
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Sano