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Kenmochi N, Ida K, Tokuzawa T, Yasuhara R, Funaba H, Uehara H, Den Hartog DJ, Yamada I, Yoshinuma M, Takemura Y, Igami H. Preceding propagation of turbulence pulses at avalanche events in a magnetically confined plasma. Sci Rep 2022; 12:6979. [PMID: 35577787 PMCID: PMC9110360 DOI: 10.1038/s41598-022-10499-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/11/2022] [Indexed: 11/09/2022] Open
Abstract
The preceding propagation of turbulence pulses has been observed for the first time in heat avalanche events during the collapse of the electron internal transport barrier (e-ITB) in the Large Helical Device. The turbulence and heat pulses are generated near the foot of the e-ITB and propagate to the peripheral region within a much shorter time than the diffusion timescale. The propagation speed of the turbulence pulse is approximately 10 km/s, which is faster than that of the heat pulse propagating at a speed of 1.5 km/s. The heat pulse propagates at approximately the same speed as that in the theoretical prediction, whereas the turbulence pulse propagates one order of magnitude faster than that in the prediction, thereby providing important insights into the physics of non-local transport.
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Affiliation(s)
- N Kenmochi
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan.
| | - K Ida
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - T Tokuzawa
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - R Yasuhara
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
| | - H Funaba
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
| | - H Uehara
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - D J Den Hartog
- Wisconsin Plasma Physics Laboratory, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - I Yamada
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
| | - M Yoshinuma
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - Y Takemura
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - H Igami
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
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Ghendrih P, Ciraolo G, Dif-Pradalier G, Norscini C, Sarazin Y, Abiteboul J, Cartier-Michaud T, Garbet X, Grandgirard V, Strugarek A. Fusion plasma turbulence described by modified sandpile dynamics. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2014; 37:27. [PMID: 24771234 DOI: 10.1140/epje/i2014-14027-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Revised: 01/19/2014] [Accepted: 02/11/2014] [Indexed: 06/03/2023]
Abstract
Transport in fusion plasmas is investigated with modified sandpile models. Based on results from more complete simulations, the sandpile model is modified in steps. Models with a constant source are obtained by coupling two sandpiles. Decoupling the mean field from the bursts allows one to develop a reduced model which captures some of the key features of flux-driven simulations. In the latter sandpile model, turbulent transport is mediated by the burst field while the mean-field gradient governs the transfer to the bursts. This allows one to investigate spreading, namely turbulent transport into stable regions, and transport barriers, regions where the transfer from the mean field to turbulence is reduced. Both cases are found to exhibit intermittent behaviors when the system undergoes spontaneous transitions between different transport regimes. Finally, one couples to the sandpile algorithm a species evolution algorithm that assigns a quality factor to each site. The latter appears to self-generate corrugations, or micro-barriers. These are found to naturally cluster radially in structures that are large enough to impact confinement. The mechanisms introduced to alleviate the clustering, destabilization of the corrugation by overloading and by secondary instabilities at critical radial extents, are shown to generate long-range relaxation events in space and in time with quasiperiodic reorganization of the corrugation pattern.
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Sonnino G, Steinbrecher G, Cardinali A, Sonnino A, Tlidi M. Family of probability distributions derived from maximal entropy principle with scale invariant restrictions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:014104. [PMID: 23410470 DOI: 10.1103/physreve.87.014104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Indexed: 06/01/2023]
Abstract
Using statistical thermodynamics, we derive a general expression of the stationary probability distribution for thermodynamic systems driven out of equilibrium by several thermodynamic forces. The local equilibrium is defined by imposing the minimum entropy production and the maximum entropy principle under the scale invariance restrictions. The obtained probability distribution presents a singularity that has immediate physical interpretation in terms of the intermittency models. The derived reference probability distribution function is interpreted as time and ensemble average of the real physical one. A generic family of stochastic processes describing noise-driven intermittency, where the stationary density distribution coincides exactly with the one resulted from entropy maximization, is presented.
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Affiliation(s)
- Giorgio Sonnino
- Department of Theoretical Physics and Mathematics, Université Libre de Bruxelles (U.L.B.), Campus de la Plaine C.P. 231, Boulevard du Triomphe, 1050 Brussels, Belgium.
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Sattin F, Baiesi M. Self-organized-criticality model consistent with statistical properties of edge turbulence in a fusion plasma. PHYSICAL REVIEW LETTERS 2006; 96:105005. [PMID: 16605745 DOI: 10.1103/physrevlett.96.105005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Indexed: 05/08/2023]
Abstract
The statistical properties of the intermittent signal generated by a recent model for self-organized criticality are examined. A successful comparison is made with previously published results of the equivalent quantities measured in the electrostatic turbulence at the edge of a fusion plasma. This result reestablishes self-organized criticality as a potential paradigm for transport in magnetic fusion devices, overriding shortcomings pointed out in earlier works [E. Spada, Phys. Rev. Lett. 86, 3032 (2001)10.1103/PhysRevLett.86.3032; V. Antoni, Phys. Rev. Lett. 87, 045001 (2001)10.1103/PhysRevLett.87.045001].
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Affiliation(s)
- Fabio Sattin
- Consorzio RFX, ENEA-Euratom Association, Corso Stati Uniti 4, 35127 Padova, Italy.
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Tangri V, Das A, Kaw P, Singh R. Continuum self-organized-criticality model of turbulent heat transport in tokamaks. PHYSICAL REVIEW LETTERS 2003; 91:025001. [PMID: 12906484 DOI: 10.1103/physrevlett.91.025001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2002] [Indexed: 05/24/2023]
Abstract
A simple generic one-dimensional continuum model of driven dissipative systems is proposed to explain self-organized bursty heat transport in tokamaks. Extensive numerical simulations of this model reproduce many features of present day tokamaks such as submarginal temperature profiles, intermittent transport events, 1/f scaling of the frequency spectra, propagating fronts, etc. This model utilizes a minimal set of phenomenological parameters, which may be determined from experiments and/or simulations. Analytical and physical understanding of the observed features has also been attempted.
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Affiliation(s)
- Varun Tangri
- Institute for Plasma Research, Bhat, Gandhinagar 382428, India
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