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Purohit S, Suzuki Y, Ohdachi S, Yamamoto S. Improved design for Heliotron J soft X-ray diagnostic for tomographic reconstruction studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10G102. [PMID: 30399660 DOI: 10.1063/1.5038953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/12/2018] [Indexed: 06/08/2023]
Abstract
Identifications of the plasma boundary shape and mode structure are important problems for the studies of the magnetohydrodynamics equilibrium and stability studies. Imaging diagnostics have the possibility to measure the plasma boundary shape and mode structure directly. The soft X-ray (SX) tomography is an imaging diagnostic for offering these direct measurements. However, SX tomography is by nature a limited angle tomography and provides a challenge as an ill-condition inverse problem. The reconstructed profiles depend heavily on the quality of measurements along with the employed inversion algorithm. This paper provides a detailed description of tomographic reconstruction of simulated SX measurements from the current SX diagnostic design of Heliotron J (H-J), which is a medium size heliotron device. Heliotron J has a unique magnetic geometry, and the quantitative identification of the plasma boundary and mode structure is a critical problem. The Phillip-Tikhonov regularization is employed to address the inversion problem. Finally, a new design for Heliotron J soft X-ray diagnostic is discussed which holds enhanced capabilities for tomographic reconstructions especially for the high poloidal number perturbations.
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Affiliation(s)
- S Purohit
- SOKENDAI, The Graduate University for Advanced Studies, 322-6 Oroshi-cho Toki, Gifu 509-5292, Japan
| | - Y Suzuki
- SOKENDAI, The Graduate University for Advanced Studies, 322-6 Oroshi-cho Toki, Gifu 509-5292, Japan
| | - S Ohdachi
- SOKENDAI, The Graduate University for Advanced Studies, 322-6 Oroshi-cho Toki, Gifu 509-5292, Japan
| | - S Yamamoto
- Institute of Advanced Energy, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan
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Toi K, Isobe M, Osakabe M, Watanabe F, Ogawa K, Yamamoto S, Nakajima N, Spong DA, Ida K, Ido T, Ito T, Morita S, Nagaoka K, Narihara K, Nishiura M, Ohdachi S, Sakakibara S, Shimizu A, Tanaka K, Todo Y, Tokuzawa T, Weller A. MHD Modes Destabilized by Energetic Ions on LHD. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst10-a10805] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- K. Toi
- National Institute for Fusion Science, Toki, Japan
| | - M. Isobe
- National Institute for Fusion Science, Toki, Japan
| | - M. Osakabe
- National Institute for Fusion Science, Toki, Japan
| | - F. Watanabe
- Department of Energy Engineering and Science, Nagoya University, Nagoya, Japan
| | - K. Ogawa
- Department of Energy Engineering and Science, Nagoya University, Nagoya, Japan
| | - S. Yamamoto
- Institute of Advanced Energy, Kyoto University, Uji, Japan
| | - N. Nakajima
- National Institute for Fusion Science, Toki, Japan
| | - D. A. Spong
- Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - K. Ida
- National Institute for Fusion Science, Toki, Japan
| | - T. Ido
- National Institute for Fusion Science, Toki, Japan
| | - T. Ito
- Department of Energy Engineering and Science, Nagoya University, Nagoya, Japan
| | - S. Morita
- National Institute for Fusion Science, Toki, Japan
| | - K. Nagaoka
- National Institute for Fusion Science, Toki, Japan
| | - K. Narihara
- National Institute for Fusion Science, Toki, Japan
| | - M. Nishiura
- National Institute for Fusion Science, Toki, Japan
| | - S. Ohdachi
- National Institute for Fusion Science, Toki, Japan
| | | | - A. Shimizu
- National Institute for Fusion Science, Toki, Japan
| | - K. Tanaka
- National Institute for Fusion Science, Toki, Japan
| | - Y. Todo
- National Institute for Fusion Science, Toki, Japan
| | - T. Tokuzawa
- National Institute for Fusion Science, Toki, Japan
| | - A. Weller
- Max-Planck Institut für Plasma Physik, Greifswald, Germany
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Ohshima S, Kobayashi S, Yamamoto S, Nagasaki K, Mizuuchi T, Kado S, Okada H, Minami T, Lee HY, Zang L, Kenmochi N, Kasajima K, Ohtani Y, Shi N, Nagae Y, Konoshima S, Sano F. Highly time-resolved evaluation technique of instantaneous amplitude and phase difference using analytic signals for multi-channel diagnostics. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:11E814. [PMID: 25430379 DOI: 10.1063/1.4891102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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.
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Affiliation(s)
- S Ohshima
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - S Kobayashi
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - S Yamamoto
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K Nagasaki
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - T Mizuuchi
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - S Kado
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - H Okada
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - T Minami
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - H Y Lee
- Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea
| | - L Zang
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - N Kenmochi
- Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K Kasajima
- Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Y Ohtani
- Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - N Shi
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Y Nagae
- Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - S Konoshima
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - F Sano
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
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Kobayashi S, Kado S, Oishi T, Ohshima S, Kagawa T, Nagae Y, Yamamoto S, Mizuuchi T, Nagasaki K, Okada H, Minami T, Estrada T, Murakami S, Lee HY, Minami T, Harada T, Nakamura Y, Konoshima S, Toushi K, Sano F. Density fluctuation measurements using beam emission spectroscopy on Heliotron J. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:10D535. [PMID: 23126873 DOI: 10.1063/1.4734039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This paper describes the measurement of the density fluctuation using beam emission spectroscopy in Heliotron J, having the non-symmetrical helical-magnetic-axis configuration. In order to optimize the sightlines, the numerical calculations are carried out to estimate the spatial resolution and the observation location. When a tangential neutral beam is used as diagnostic one, suitable sightlines from the newly installed diagnostic port are selected whose spatial resolution Δρ is less than ± 0.07 over the entire plasma region. Modification of the interference filter and the detection systems enables us to measure the radial profile of the density fluctuation. Each of the three coherent modes due to the fast-ion-driven magnetohydrodynamic instabilities has different radial structure of the density fluctuation.
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Affiliation(s)
- S Kobayashi
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
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