量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Numerical diagnostics using 3D simulation data are carried out to capture fluctuation properties in helical plasmas. Here, ion-temperature-gradient (ITG) turbulence data are used and obtained by the gyrokinetic code, GKV-X, with realistic magnetic configuration. Fluctuations are calculated in the field aligned coordinates, which have long wave lengths in the magnetic field direction and are anisotropic in the radial and poloidal directions; their features are represented in the experimental frame. For the validation, the density fluctuation spectrum is calculated, which is integrated along the line of sight as in the phase contrast imaging signals. From that integrated signal, its vertical profile is reconstructed by utilizing the variation of the direction of the magnetic field, as the operation carried out in experimental data. In experiments, there usually exists a limitation on the observation region and spatial resolution, so differences between the deteriorated and real spectra is confirmed by numerical simulations with variations related to spatial limitations. ITG modes have a characteristic wavelength and frequency, and are identified with sufficient spatial resolution even from the integrated signal by comparing the wavemunber spectra at different radial positions. Combination of multiple flux-tube data is also tested for calculation to give fluctuations spreading in wider radial ranges of plasma. These fluctuation spectra are compared with the experimental one for comprehensive understanding of experimental observations.
Numerical diagnostics of fluctuation spectrum in 3D magnetic configurations
