1
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Kobayashi T, Sasaki M, Ido T, Kamiya K, Miura Y, Nagashima Y, Ida K, Inagaki S, Fujisawa A, Itoh SI, Itoh K. Quantification of Turbulent Driving Forces for the Geodesic Acoustic Mode in the JFT-2M Tokamak. Phys Rev Lett 2018; 120:045002. [PMID: 29437414 DOI: 10.1103/physrevlett.120.045002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/29/2017] [Indexed: 06/08/2023]
Abstract
We investigate spatial structures of turbulence and turbulent transport modulated by the geodesic acoustic mode (GAM), from which the excitation mechanism of the GAM is discussed. The GAM is found to be predominantly excited through a localized Reynolds stress force, rather than the dynamic shearing force. The evaluated growth rate is larger than the linear damping coefficients and is on the same order of magnitude as the effective growth rate evaluated from time evolution in the GAM kinetic energy.
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Affiliation(s)
- T Kobayashi
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
| | - M Sasaki
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - T Ido
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
| | - K Kamiya
- National Institutes for Quantum and Radiological Science and Technology, Naka 311-0193, Japan
| | - Y Miura
- Japan Atomic Energy Agency, Naka 311-0193, Japan
| | - Y Nagashima
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - K Ida
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - S Inagaki
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - A Fujisawa
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - K Itoh
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
- Institute of Science and Technology Research, Chubu University, Kasugai 487-8501, Japan
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2
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Kobayashi T, Itoh K, Ido T, Kamiya K, Itoh SI, Miura Y, Nagashima Y, Fujisawa A, Inagaki S, Ida K. Turbulent transport reduction induced by transition on radial electric field shear and curvature through amplitude and cross-phase in torus plasma. Sci Rep 2017; 7:14971. [PMID: 29097702 PMCID: PMC5668279 DOI: 10.1038/s41598-017-14821-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/16/2017] [Indexed: 11/23/2022] Open
Abstract
Spatiotemporal evolutions of radial electric field and turbulence are measured simultaneously in the H-mode transition, which is a prototypical example of turbulence structure formation in high-temperature plasmas. In the dynamical phase where transport barrier is established abruptly, the time-space-frequency-resolved turbulent particle flux is obtained. Here we report the validation of the mechanism of transport barrier formation quantitatively. It is found that the particle flux is suppressed predominantly by reducing density fluctuation amplitude and cross phase between density fluctuation and potential fluctuation. Both radial electric field shear and curvature are responsible for the amplitude suppression as was predicted by theory. Turbulence amplitude reduction immediately responds to the growth of the radial electric field non-uniformity and saturates, while cross phase continuously approaches zero.
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Affiliation(s)
- T Kobayashi
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.
| | - K Itoh
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.,Institute of Science and Technology Research, Chubu University, Kasugai, 487-8501, Japan.,Research Center for Plasma Turbulence, Kyushu University, Kasuga, 816-8580, Japan
| | - T Ido
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan
| | - K Kamiya
- National Institute for Quantum and Radiological Science and Technology, Naka, 311-0193, Japan
| | - S-I Itoh
- Research Center for Plasma Turbulence, Kyushu University, Kasuga, 816-8580, Japan.,Research Institute for Applied Mechanics, Kyushu University, Kasuga, 816-8580, Japan
| | - Y Miura
- Japan Atomic Energy Agency, Tokai, 319-1184, Japan
| | - Y Nagashima
- Research Center for Plasma Turbulence, Kyushu University, Kasuga, 816-8580, Japan.,Research Institute for Applied Mechanics, Kyushu University, Kasuga, 816-8580, Japan
| | - A Fujisawa
- Research Center for Plasma Turbulence, Kyushu University, Kasuga, 816-8580, Japan.,Research Institute for Applied Mechanics, Kyushu University, Kasuga, 816-8580, Japan
| | - S Inagaki
- Research Center for Plasma Turbulence, Kyushu University, Kasuga, 816-8580, Japan.,Research Institute for Applied Mechanics, Kyushu University, Kasuga, 816-8580, Japan
| | - K Ida
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.,Research Center for Plasma Turbulence, Kyushu University, Kasuga, 816-8580, Japan
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3
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Abstract
A calculation which describes the spin-up of toroidal plasmas by the radial propagation of turbulence fronts with broken parallel symmetry is presented. The associated flux of parallel momentum is calculated by using a two-scale direct-interaction approximation in the weak turbulence limit. We show that fluctuation momentum spreads faster than mean flow momentum. Specifically, the turbulent flux of wave momentum is stronger than the momentum pinch. The scattering of fluctuation momentum can induce edge-core coupling of toroidal flows, as observed in experiments.
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Affiliation(s)
- Y Kosuga
- Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan.,Research Center for Plasma Turbulence, Kyushu University, Fukuoka, Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan.,Research Center for Plasma Turbulence, Kyushu University, Fukuoka, Japan
| | - P H Diamond
- University of California, San Diego, La Jolla, California 92093, USA
| | - K Itoh
- Research Center for Plasma Turbulence, Kyushu University, Fukuoka, Japan.,National Institute for Fusion Science, Gifu, Japan
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4
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Zhao KJ, Nagashima Y, Diamond PH, Dong JQ, Itoh K, Itoh SI, Yan LW, Cheng J, Fujisawa A, Inagaki S, Kosuga Y, Sasaki M, Wang ZX, Wei L, Huang ZH, Yu DL, Hong WY, Li Q, Ji XQ, Song XM, Huang Y, Liu Y, Yang QW, Ding XT, Duan XR. Synchronization of Geodesic Acoustic Modes and Magnetic Fluctuations in Toroidal Plasmas. Phys Rev Lett 2016; 117:145002. [PMID: 27740841 DOI: 10.1103/physrevlett.117.145002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Indexed: 06/06/2023]
Abstract
The synchronization of geodesic acoustic modes (GAMs) and magnetic fluctuations is identified in the edge plasmas of the HL-2A tokamak. Mesoscale electric fluctuations (MSEFs) having components of a dominant GAM, and m/n=6/2 potential fluctuations are found at the same frequency as that of the magnetic fluctuations of m/n=6/2 (m and n are poloidal and toroidal mode numbers, respectively). The temporal evolutions of the MSEFs and the magnetic fluctuations clearly show the frequency entrainment and the phase lock between the GAM and the m/n=6/2 magnetic fluctuations. The results indicate that GAMs and magnetic fluctuations can transfer energy through nonlinear synchronization. Such nonlinear synchronization may also contribute to low-frequency zonal flow formation, reduction of turbulence level, and thus confinement regime transitions.
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Affiliation(s)
- K J Zhao
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - Y Nagashima
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Kasuga koen 6-1, 816-8580, Japan
| | - P H Diamond
- Center for Momentum Transport and Flow Organization, University of California at San Diego, California, San Diego 92093, USA
| | - J Q Dong
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
- Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, China
| | - K Itoh
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Kasuga koen 6-1, 816-8580, Japan
| | - L W Yan
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - J Cheng
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - A Fujisawa
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Kasuga koen 6-1, 816-8580, Japan
| | - S Inagaki
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Kasuga koen 6-1, 816-8580, Japan
| | - Y Kosuga
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Kasuga koen 6-1, 816-8580, Japan
| | - M Sasaki
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Kasuga koen 6-1, 816-8580, Japan
| | - Z X Wang
- School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China
| | - L Wei
- School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China
| | - Z H Huang
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - D L Yu
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - W Y Hong
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - Q Li
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - X Q Ji
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - X M Song
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - Y Huang
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - Yi Liu
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - Q W Yang
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - X T Ding
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
| | - X R Duan
- Southwestern Institute of Physics, P.O. Box 432, Chendu 610041, China
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5
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Kamiya K, Itoh K, Itoh SI. Experimental validation of non-uniformity effect of the radial electric field on the edge transport barrier formation in JT-60U H-mode plasmas. Sci Rep 2016; 6:30585. [PMID: 27480931 PMCID: PMC4969757 DOI: 10.1038/srep30585] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 07/04/2016] [Indexed: 11/22/2022] Open
Abstract
The turbulent structure formation, where strongly-inhomogeneous turbulence and global electromagnetic fields are self-organized, is a fundamental mechanism that governs the evolution of high-temperature plasmas in the universe and laboratory (e.g., the generation of edge transport barrier (ETB) of the H-mode in the toroidal plasmas). The roles of inhomogeneities of radial electric field (Er) are known inevitable. In this mechanism, whether the first derivative of Er (shear) or the second derivative of Er (curvature) works most is decisive in determining the class of nontrivial solutions (which describe the barrier structure). Here we report the experimental identification of the essential role of the Er-curvature on the ETB formation, for the first time, based on the high-spatiotemporal resolution spectroscopic measurement. We found the decisive importance of Er-curvature on ETB formation during ELM-free phase, but there is only a low correlation with the Er-shear value at the peak of normalized ion temperature gradient. Furthermore, in the ELMing phase, the effect of curvature is also quantified in terms of the relationship between pedestal width and thickness of the layer of inhomogeneous Er. This is the fundamental basis to understand the structure of transport barriers in fusion plasmas.
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Affiliation(s)
- K Kamiya
- National Institutes for Quantum and Radiological Science and Technology (QST), Naka, Ibaraki-ken 311-0193, Japan
| | - K Itoh
- National Institute for Fusion Science (NIFS), Toki, Gifu 509-5292, Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Kasuga koen 6-1, 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
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6
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Inagaki S, Kobayashi T, Kosuga Y, Itoh SI, Mitsuzono T, Nagashima Y, Arakawa H, Yamada T, Miwa Y, Kasuya N, Sasaki M, Lesur M, Fujisawa A, Itoh K. A Concept of Cross-Ferroic Plasma Turbulence. Sci Rep 2016; 6:22189. [PMID: 26917218 PMCID: PMC4768185 DOI: 10.1038/srep22189] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 02/08/2016] [Indexed: 11/18/2022] Open
Abstract
The variety of scalar and vector fields in laboratory and nature plasmas is formed by plasma turbulence. Drift-wave fluctuations, driven by density gradients in magnetized plasmas, are known to relax the density gradient while they can generate flows. On the other hand, the sheared flow in the direction of magnetic fields causes Kelvin-Helmholtz type instabilities, which mix particle and momentum. These different types of fluctuations coexist in laboratory and nature, so that the multiple mechanisms for structural formation exist in extremely non-equilibrium plasmas. Here we report the discovery of a new order in plasma turbulence, in which chained structure formation is realized by cross-interaction between inhomogeneities of scalar and vector fields. The concept of cross-ferroic turbulence is developed, and the causal relation in the multiple mechanisms behind structural formation is identified, by measuring the relaxation rate and dissipation power caused by the complex turbulence-driven flux.
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Affiliation(s)
- S Inagaki
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - T Kobayashi
- National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-city, Gifu 509-5292, Japan
| | - Y Kosuga
- Institute for Advanced Study, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, 812-8581, Fukuoka Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - T Mitsuzono
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan
| | - Y Nagashima
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - H Arakawa
- Teikyo University, 6-22 Misaki-machi, Omuta-city, Fukuoka 836-8505, Japan
| | - T Yamada
- Faculty of Arts and Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Y Miwa
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan
| | - N Kasuya
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - M Sasaki
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - M Lesur
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan
| | - A Fujisawa
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580, Japan.,Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan
| | - K Itoh
- Research Center for Plasma Turbulence, Kyushu University, 6-1 Kasuga-Koen, Kasuga-city, Fukuoka 816-8580 Japan.,National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-city, Gifu 509-5292, Japan
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7
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Lesur M, Itoh K, Ido T, Osakabe M, Ogawa K, Shimizu A, Sasaki M, Ida K, Inagaki S, Itoh SI. Nonlinear Excitation of Subcritical Instabilities in a Toroidal Plasma. Phys Rev Lett 2016; 116:015003. [PMID: 26799024 DOI: 10.1103/physrevlett.116.015003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Indexed: 06/05/2023]
Abstract
In a collisionless plasma, it is known that linearly stable modes can be destabilized (subcritically) by the presence of structures in phase space. However, nonlinear growth requires the presence of a seed structure with a relatively large threshold in amplitude. We demonstrate that, in the presence of another, linearly unstable (supercritical) mode, wave-wave coupling can provide a seed, which is significantly below the threshold, but can still grow by (and only by) the collaboration of fluid and kinetic nonlinearities. By modeling the subcritical mode kinetically, and the impact of the supercritical mode by simple wave-wave coupling equations, it is shown that this new kind of subcritical instability can be triggered, even when the frequency of the supercritical mode is rapidly sweeping. The model is applied to the bursty onset of geodesic acoustic modes in a LHD experiment. The model recovers several key features such as relative amplitude, time scales, and phase relations. It suggests that the strongest bursts are subcritical instabilities, driven by this mechanism of combined fluid and kinetic nonlinearities.
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Affiliation(s)
- M Lesur
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
| | - K Itoh
- National Institute for Fusion Science, Toki 509-5292, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - T Ido
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - M Osakabe
- National Institute for Fusion Science, Toki 509-5292, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292, Japan
| | - K Ogawa
- National Institute for Fusion Science, Toki 509-5292, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292, Japan
| | - A Shimizu
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - M Sasaki
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - K Ida
- National Institute for Fusion Science, Toki 509-5292, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292, Japan
| | - S Inagaki
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
- Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
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8
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Ido T, Itoh K, Osakabe M, Lesur M, Shimizu A, Ogawa K, Toi K, Nishiura M, Kato S, Sasaki M, Ida K, Inagaki S, Itoh SI. Strong Destabilization of Stable Modes with a Half-Frequency Associated with Chirping Geodesic Acoustic Modes in the Large Helical Device. Phys Rev Lett 2016; 116:015002. [PMID: 26799023 DOI: 10.1103/physrevlett.116.015002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 06/05/2023]
Abstract
Abrupt and strong excitation of a mode has been observed when the frequency of a chirping energetic-particle driven geodesic acoustic mode (EGAM) reaches twice the geodesic acoustic mode (GAM) frequency. The frequency of the secondary mode is the GAM frequency, which is a half-frequency of the primary EGAM. Based on the analysis of spatial structures, the secondary mode is identified as a GAM. The phase relation between the secondary mode and the primary EGAM is locked, and the evolution of the growth rate of the secondary mode indicates nonlinear excitation. The results suggest that the primary mode (EGAM) contributes to nonlinear destabilization of a subcritical mode.
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Affiliation(s)
- T Ido
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - K Itoh
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - M Osakabe
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
- SOKENDAI (The Graduate University for Advanced Study), 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - M Lesur
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
| | - A Shimizu
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - K Ogawa
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
- SOKENDAI (The Graduate University for Advanced Study), 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - K Toi
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - M Nishiura
- Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanohara, Kashiwa, Chiba 277-8561, Japan
| | - S Kato
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - M Sasaki
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
| | - K Ida
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
- SOKENDAI (The Graduate University for Advanced Study), 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - S Inagaki
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
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9
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Kobayashi T, Birkenmeier G, Wolfrum E, Laggner FM, Willensdorfer M, Stroth U, Inagaki S, Itoh SI, Itoh K. Method for estimating the propagation direction of a coherent plasma structure using a one-dimensional diagnostic array. Rev Sci Instrum 2014; 85:083507. [PMID: 25173269 DOI: 10.1063/1.4893482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This article proposes a new method to evaluate basic characteristics of the dynamics of a coherent plasma structure (blob). With this method, one can evaluate the propagation angle of a blob in a two-dimensional plasma cross section as well as the blob velocity, size, and amplitude from one-dimensional data. The method is applied to blob measurements from the Lithium beam emission spectroscopy system in ASDEX-Upgrade. Statistical features of the observed blob velocities, angles of propagation, blob sizes, and amplitudes are discussed. The validity of the method is examined by comparing two values of the propagation angle that are evaluated in an independent manner.
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Affiliation(s)
- T Kobayashi
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816-8580, Japan
| | - G Birkenmeier
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - E Wolfrum
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - F M Laggner
- Institute of Applied Physics, Vienna University of Technology, 1040 Vienna, Austria
| | - M Willensdorfer
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - U Stroth
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - S Inagaki
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
| | - S-I Itoh
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
| | - K Itoh
- National Institute for Fusion Science, Toki 509-5292, Japan
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10
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Kobayashi T, Itoh K, Ido T, Kamiya K, Itoh SI, Miura Y, Nagashima Y, Fujisawa A, Inagaki S, Ida K, Hoshino K. Spatiotemporal structures of edge limit-cycle oscillation before L-to-H transition in the JFT-2M tokamak. Phys Rev Lett 2013; 111:035002. [PMID: 23909334 DOI: 10.1103/physrevlett.111.035002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Indexed: 06/02/2023]
Abstract
In this Letter, we report analyses of spatiotemporal dynamics of turbulence and structure in the limit-cycle oscillation (LCO) that precedes an L-to-H transition. Zonal flows are not observed during LCO, and the oscillation is the periodic generations or decays of barrier with edge-localized mean flow. Oscillatory Reynolds stress is found to be too small to accelerate the LCO flow, by considering the dielectric constant in magnetized toroidal plasmas. Propagation of changes of the density gradient and turbulence amplitude into the core is also observed.
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Affiliation(s)
- T Kobayashi
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816-8580, Japan.
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Cheng J, Dong JQ, Itoh K, Yan LW, Xu M, Zhao KJ, Hong WY, Huang ZH, Ji XQ, Zhong WL, Yu DL, Itoh SI, Nie L, Kong DF, Lan T, Liu AD, Zou XL, Yang QW, Ding XT, Duan XR, Liu Y. Dynamics of low-intermediate-high-confinement transitions in toroidal plasmas. Phys Rev Lett 2013; 110:265002. [PMID: 23848884 DOI: 10.1103/physrevlett.110.265002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Indexed: 06/02/2023]
Abstract
The dynamic features of the low-intermediate-high-(L-I-H) confinement transitions on HL-2A tokamak are presented. Here we report the discovery of two types of limit cycles (dubbed type-Y and type-J), which show opposite temporal ordering between the radial electric field and turbulence intensity. In type-Y, which appears first after an L-I transition, the turbulence grows first, followed by the localized electric field. In contrast, the electric field leads type-J. The turbulence-induced zonal flow and pressure-gradient-induced drift play essential roles in the two types of limit cycles, respectively. The condition of transition between types-Y and -J is studied in terms of the normalized radial electric field. An I-H transition is demonstrated to occur only from type-J.
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Affiliation(s)
- J Cheng
- Southwestern Institute of Physics, Chengdu 610041, People's Republic of China
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12
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Inagaki S, Tokuzawa T, Itoh K, Ida K, Itoh SI, Tamura N, Sakakibara S, Kasuya N, Fujisawa A, Kubo S, Shimozuma T, Ido T, Nishimura S, Arakawa H, Kobayashi T, Tanaka K, Nagayama Y, Kawahata K, Sudo S, Yamada H, Komori A. Observation of long-distance radial correlation in toroidal plasma turbulence. Phys Rev Lett 2011; 107:115001. [PMID: 22026678 DOI: 10.1103/physrevlett.107.115001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Indexed: 05/31/2023]
Abstract
This Letter presents the discovery of macroscale electron temperature fluctuations with a long radial correlation length comparable to the plasma minor radius in a toroidal plasma. Their spatiotemporal structure is characterized by a low frequency of ∼1-3 kHz, ballistic radial propagation, a poloidal or toroidal mode number of m/n=1/1 (or 2/1), and an amplitude of ∼2% at maximum. Nonlinear coupling between the long-range fluctuations and the microscopic fluctuations is identified. A change of the amplitude of the long-range fluctuation is transmitted across the plasma radius at the velocity which is of the order of the drift velocity.
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Affiliation(s)
- S Inagaki
- Research Institute for Applied Mechanics, Kyushu University, Fukuoka 816-8580, Japan
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13
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Yamada T, Itoh SI, Inagaki S, Nagashima Y, Kasuya N, Kamataki K, Arakawa H, Kobayashi T, Yagi M, Fujisawa A, Itoh K. Observation of quasi-two-dimensional nonlinear interactions in a drift-wave streamer. Phys Rev Lett 2010; 105:225002. [PMID: 21231392 DOI: 10.1103/physrevlett.105.225002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Indexed: 05/30/2023]
Abstract
A streamer, which is a bunching of drift-wave fluctuations, and its mediator, which generates the streamer by coupling with other fluctuations, have been observed in a cylindrical magnetized plasma. Their radial structures were investigated in detail by using the biphase analysis. Their quasi-two-dimensional structures were revealed to be equivalent with a pair of fast and slow modes predicted by a nonlinear Schrödinger equation based on the Hasegawa-Mima model.
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Affiliation(s)
- T Yamada
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan.
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14
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Yamada T, Nagashima Y, Inagaki S, Kawai Y, Yagi M, Itoh SI, Maruta T, Shinohara S, Terasaka K, Kawaguchi M, Fukao M, Fujisawa A, Itoh K. Fine positioning of a poloidal probe array. Rev Sci Instrum 2007; 78:123501. [PMID: 18163726 DOI: 10.1063/1.2818796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Multipoint detection is an essential requirement for investigating plasma turbulence which is a highly nonlinear phenomenon in space and time. We have fabricated an array of 64-channel poloidal probes surrounding the linear cylindrical plasma named LMD-U in order to study turbulence properties, particularly the nonlinear mode couplings, in the domain of poloidal wave number and frequency. However, misalignments of probe tips produce spurious modes, which do not exist in the real plasma, to distort the precise wave number measurements. The paper presents the description of the 64-channel poloidal probe array with means to adjust the probe positions, with discussion on the effects of the misalignments on the wave number measurements.
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Affiliation(s)
- T Yamada
- Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan.
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15
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Fujisawa A, Itoh K, Shimizu A, Nakano H, Ohshima S, Iguchi H, Matsuoka K, Okamura S, Minami T, Yoshimura Y, Nagaoka K, Ida K, Toi K, Takahashi C, Kojima M, Nishimura S, Isobe M, Suzuki C, Akiyama T, Nagashima Y, Itoh SI, Diamond PH. Experimental evidence of a zonal magnetic field in a toroidal plasma. Phys Rev Lett 2007; 98:165001. [PMID: 17501426 DOI: 10.1103/physrevlett.98.165001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Indexed: 05/15/2023]
Abstract
A zonal magnetic field is found in a toroidal plasma. The magnetic field has a symmetric bandlike structure, which is uniform in the toroidal and poloidal directions and varies radially with a finite wavelength of mesoscale, which is analogous to zonal flows. A time-dependent bicoherence analysis reveals that the magnetic field should be generated by the background plasma turbulence. The discovery is classified as a new kind of phenomenon of structured magnetic field generation, giving insight into phenomena such as dipole field generation in rotational planets.
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Affiliation(s)
- A Fujisawa
- National Institute for Fusion Science, Oroshi-cho, Toki-shi 509-52, Japan
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16
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Fujisawa A, Itoh K, Iguchi H, Matsuoka K, Okamura S, Shimizu A, Minami T, Yoshimura Y, Nagaoka K, Takahashi C, Kojima M, Nakano H, Ohsima S, Nishimura S, Isobe M, Suzuki C, Akiyama T, Ida K, Toi K, Itoh SI, Diamond PH. Identification of zonal flows in a toroidal plasma. Phys Rev Lett 2004; 93:165002. [PMID: 15524996 DOI: 10.1103/physrevlett.93.165002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Indexed: 05/24/2023]
Abstract
This Letter presents experimental confirmation of the presence of zonal flows in magnetically confined toroidal plasma using an advanced diagnostic system--dual heavy ion beam probes. The simultaneous observation of an electric field at two distant toroidal locations (approximately 1.5 m apart) in the high temperature (approximately 1 keV) plasma provides a fluctuation spectrum of electric field (or flow), a spatiotemporal structure of the zonal flows (characteristic radial length of approximately 1.5 cm and lifetime of approximately 1.5 ms), their long-range correlation with toroidal symmetry (n=0), and the difference in the zonal flow amplitude with and without a transport barrier. These constitute essential elements of turbulence-zonal flow systems, and illustrate one of the fundamental processes of structure formation in nature.
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Affiliation(s)
- A Fujisawa
- National Institute for Fusion Science, Oroshi-cho, Toki-shi, 509-52 Japan
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17
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Spineanu F, Vlad M, Itoh K, Sanuki H, Itoh SI. Pole dynamics for the flierl-petviashvili equation and zonal flow. Phys Rev Lett 2004; 93:025001. [PMID: 15323923 DOI: 10.1103/physrevlett.93.025001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2003] [Indexed: 05/24/2023]
Abstract
Using the method of positions of the complex singularities, we identify a class of new, exact solutions of the Flierl-Petviashvili equation. The solutions are periodic and have the geometry of the zonal flow. We examine the physical properties and find that the solution can reproduce data from experimental observations and numerical simulations.
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Affiliation(s)
- F Spineanu
- National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-shi, Gifu-ken 509-5292, Japan
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18
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Yokoyama M, Itoh K, Okamura S, Matsuoka K, Itoh SI. Maximum-J capability in a quasiaxisymmetric stellarator. Phys Rev E Stat Nonlin Soft Matter Phys 2001; 64:015401. [PMID: 11461322 DOI: 10.1103/physreve.64.015401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2001] [Indexed: 05/23/2023]
Abstract
Maximum-J (J is the second adiabatic invariant) capability, i.e., the radial derivative of J has the same sign as that of pressure, is investigated in a quasiaxisymmetric (QA) stellarator to investigate improved confinement. Due to the existence of nonaxisymmetry of the magnetic field strength, a local maximum of J is created to cause the drift reversal. External controllability of the maximum-J condition is also demonstrated, by which the impact of magnetic configuration on turbulent transport can be studied.
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Affiliation(s)
- M Yokoyama
- National Institute for Fusion Science, Toki 509-5292, Japan
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Yokota S, Imagawa T, Katakura S, Itoh SI, Mitsuda T, Fujikawa S, Aihara Y. Mixed connective tissue disease in childhood: a nationwide retrospective study in Japan. Acta Paediatr Jpn 1997; 39:273-6. [PMID: 9141271 DOI: 10.1111/j.1442-200x.1997.tb03598.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Sixty-six children with mixed connective tissue disease (MCTD) were analyzed by a nationwide prospective study. The diagnostic significance of Raynaud's phenomenon and positive anti-RNP antibody was confirmed, and additional symptoms including swelling of fingers, facial erythema, and polyarthralgia, and laboratory findings such as positive rheumatoid factor, hypergammaglobulinemia, and increased levels of myogenic enzymes, were variably positive. These clinical and laboratory characteristics of MCTD were critically different from those of systemic lupus erythematosus, indicating that MCTD is an independent entity of disease.
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Affiliation(s)
- S Yokota
- Department of Pediatrics, Yokohama City University School of Medicine, Japan
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20
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Itoh SI, Itoh K, Fukuyama A, Yagi M. Edge localized modes as new bifurcation in tokamaks. Phys Rev Lett 1996; 76:920-923. [PMID: 10061585 DOI: 10.1103/physrevlett.76.920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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