Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
Yusuke Kosuga Last modified date:2020.05.20

Associate Professor / Division of Nuclear Fusion Dynamics / Research Institute for Applied Mechanics


Presentations
1. Y. Kosuga, Interplay among 3D flows in turbulent plasmas, 3rd Asia Pacific Conference on Plasma Physics, 2019.11, The helicity of flow field is an important quantity for describing topological feature of turbulent fluids and plasmas. In this work, we discuss how helicity is determined in turbulent plasmas, by considering drift wave turbulence and parallel velocity gradient driven turbulence as concrete examples. Helicity evolution for each turbulence is derived and compared against simulation data. Links between plasma helicity and transport channels, such as particle transport and momentum transport, are demonstrated. Several applications, including the excitation of 3D flow patterns in fusion plasmas and dynamo action in astrophysical plasmas are discussed..
2. Y. Kosuga, Scrape off layer width set by nonlinear streamer flows, The APTWG Mini-workshop, 2019.06.
3. Y. Kosuga, How selectively excite nonlinear streamer flows in drift wave turbulence?, Max Planck Princeton Center Workshop 2019, 2019.02.
4. Y. Kosuga, How secondary flow is selected in drift wave turbulence: Role of parallel flow shear, 2nd Asia-Pacific Conference on Plasma Physics, 2018.11.
5. Y. Kosuga, Modulational approach for the nonlinear dynamics of Langmuir wave, The First Chengdu Theory Festival, 2018.08.
6. Y. Kosuga, Modulational analysis for the flow generation by drift wave, The First Chengdu Theory Festival, 2018.08.
7. Y. Kosuga, Revisiting the excitation of radially elongated convective cells in drift wave turbulence, The 19th International Congress on Plasma Physics, 2018.06.
8. Y. Kosuga, How parallel shear flow impacts pattern selection in drift wave turbulence, 9th Festival de Theorie, 2017.07.
9. Y. Kosuga, S.-I. Itoh, P.H. Diamond, K.Itoh, How turbulence fronts induce plasma spin-up, 7th APTWG International Conference , 2017.06.
10. Y. Kosuga, S.-I. Itoh, P.H. Diamond, K.Itoh, Transport of parallel momentum by the triplet correlation in drift wave turbulence, 26th IAEA Fusion Energy Conference, 2016.10.
11. Yusuke Kosuga, Role of granulations in phase space turbulence, 17th International Congress on Plasma Physics, 2016.06.
12. Yusuke Kosuga, Role of granulations in phase space turbulence, 17th International Congress on Plasma Physics, 2016.06.
13. Y. Kosuga, S.-I. Itoh, K.Itoh, Turbulence Dynamics with the coupling of density gradient and parallel velocity gradient in the edge plasma, 15th International Workshop on Plasma Edge Theory in Fusion Devices, 2015.09.
14. Y. Kosuga, Inward particle flux driven by parallel flow shear driven instability, 8th Festival de Theorie, 2015.07.
15. LESUR MAXIME, P. H. Diamond, 小菅 佑輔, Electrostatic trapping nonlinearity, a key element of turbulent transport., 物理学会 第69回年次大会, 2014.03.
16. Maxime Lesur, 伊藤公孝, SANAE INOUE(論文のみ) ITOH, P.H. Diamond, Kosuga Yusuke, Nonlinear electrostatic trapping effects on turbulence, transport and anomalous resistivity, プラズマ•核融合学会 第30回大会, 2012.12.
17. 小菅 佑輔, 伊藤 早苗, P. H. Diamond, 伊藤公孝, LESUR MAXIME, Relative dispersion of trapped ion granulations in sheared flows, 23rd International Toki Conference, 2013.11.
18. 中西康介, Inagaki Shigeru, 小林達哉, Yoshihiko Nagashima, Takuma Yamada, 三輪裕大, Naohiro Kasuya, Makoto Sasaki, Maxime Lesur, Kosuga Yusuke, Akihide Fujisawa, SANAE INOUE(論文のみ) ITOH, 伊藤公孝, New Method for Evaluation of Ion Temperature Fluctuation in PANTA, 23rd International Toki Conference, 2013.11.
19. 小菅 佑輔, How the Propagation of Heat-Flux Modulations Triggers ExB Flow Pattern Formation, 55th Annual Meeting of the APS Division of Plasma Physics, 2013.11, E × B flow patterns are often observed to self-organize in magnetized plasmas. Recently, a new class of E×B flow pattern, called an ‘E×B staircase’, was observed in a simulation study using the full-f flux driven GYSELA code. Here, E × B staircases are quasi-regular steady patterns of localized shear layers and temperature profile corrugations. The shear layers are interspaced between regions of turbulent avalanching of the size of several correlation length (∼ 10∆c). In this work, a theory to describe the formation of such E × B staircases from a bath of stochastic avalanches is presented, based on analogy of staircase formation to jam formation in traffic flow. Namely, staircase formation is viewed as a heat flux ‘jam’ that causes profile corrugation, which is analogous to a traffic jam that causes corrugations in the local car density in a traffic flow. To model such an effect in plasmas, a finite response time τ is introduced, during which instantaneous heat flux relaxes to the mean heat flux, determined by symmetry constraints. The response time introduced here is an analogue of drivers’ response time in traffic flow dynamics. It is shown that the extended model describes a heat flux ‘jam’ and profile corrugation, which appears as an instability, in analogy to the way a clustering instability leads to a traffic jam. Such local amplification of heat and profile corrugations can lead to the formation of E × B staircases. The scale length that gives the maximum growth rate falls in the mesoscale range and is comparable to the staircase step spacing..
20. 小菅 佑輔, 伊藤 早苗, P. H. Diamond, 伊藤公孝, Toroidal momentum transport by trapped ion resonance driven ion temperature gradient driven turbulence, 14th H-mode Workshop on H-mode Physics and Transport Barriers, 2013.10.
21. 満薗友宏, Inagaki Shigeru, 小林達哉, Yoshihiko Nagashima, 三輪裕大, Naohiro Kasuya, Makoto Sasaki, Maxime Lesur, Kosuga Yusuke, Akihide Fujisawa, SANAE INOUE(論文のみ) ITOH, 伊藤公孝, Flow Structure Formation and Control in a Cylindrical Plasma, 14th H-mode Workshop on H-mode Physics and Transport Barriers, 2013.10.
22. Takuma Yamada, Inagaki Shigeru, 小林達哉, Yoshihiko Nagashima, 満薗友宏, 三輪裕大, 藤野博充, Makoto Sasaki, Naohiro Kasuya, Maxime Lesur, Kosuga Yusuke, Akihide Fujisawa, SANAE INOUE(論文のみ) ITOH, 伊藤公孝, Formation of streamer structures in linear magnetized plasmas, 14th H-mode Workshop on H-mode Physics and Transport Barriers, 2013.10.
23. Yusuke Kosuga, P.H. Diamond, O.D. Gurcan, How the radial propagation of heat flux modulations triggers ExB flow pattern formation, 7th Festival de Theorie, 2013.07.
24. Yusuke Kosuga, P.H. Diamond, O.D. Gurcan, How the radial propagation of heat flux modulations triggers ExB flow pattern formation, 3rd Asia Pacific Trasnsport Working Group, 2013.05.