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Inagaki Shigeru Last modified date:2018.06.27



Graduate School
Other Organization


E-Mail
Phone
092-583-7716
Fax
092-583-7723
Academic Degree
Doctor (Engineering)
Field of Specialization
Plasma physics and engineering
Outline Activities
Experimental study of plasma turbulence.
Our goal is clarification of physical mechanisms of global structure formation and intermittent phenomena in complex system.
Extreme sensing and time-series data analysis are developed.
Research
Research Interests
  • Dynamic Experiment of Plasma Turbulence
    keyword : dynamic response plasma turbulence
    2009.04~2013.03Turbulence transport is higher than the neoclassical level in the edge to intermediate region in helical devices (heliotron, stellarators, heliac and others) as well as in tokamaks. The turbulence causes not only quantitative features of transport but also qualitative ones. Transport dynamics reveals such qualitative features of transport. Various transient transport phenomena observed in helical plasmas indicate complexities of turbulent transport. Recent theoretical works on drift wave turbulence show drift waves are strongly coupled with micro-scale, meso-scale and macro-scale waves. These non-linear couplings form turbulent structures, which have strong influences on transport. Thus, the dynamics and the multi-scale coupling of drift waves are now the most important issues to be clarified in transport studies. A comprehensive understanding of transport dynamics through first principle turbulence models is strongly required for achieving predictive capability of turbulence transport. To study the heat transport dynamics, the transient experiments were performed in the large helical device (LHD). Dynamic transport analysis indicated a complex relationship between heat flux and temperature gradient in LHD. Moreover, an abrupt response of core temperature to an edge perturbation and a long correlation between the core heat flux and the edge temperature gradient were observed. These indicated a presence of non-local transport in helical plasmas. The non-local transport was also observed in tokamaks, and thus the non-locality is considered to be a common feature of turbulence transport in toroidal plasmas. To study the multi-scale coupling of turbulence, experimental observation of spatiotemporal structure of turbulence is essential, therefore, precise fluctuation measurements with multi-Langmuir probes were performed in the large mirror device upgrade (LMD-U). Typical experimental parameters in LMD-U were as follows: an axial length of 3.74m, a plasma radius of 6cm, a magnetic field of <0.15T, central density of 1x1019m-3 and central electron temperature of 3-4eV. New turbulence analysis method based on bi-spectrum and envelope were developed and applied to the probe data. Non-linear interactions between three waves (f1+f2=f3, k1+k2=k3, where f is mode frequency and k is poroidal wave number, respectively) were determined and thus a presence of the multi-scale coupling of drift wave was clarified..
  • Non-local Heat Transport in Magnetized Plasmas
    keyword : plasma transport turbulence non-locality
    2005.06Turbulence transport is higher than the neoclassical level in the edge to intermediate region in helical devices (heliotron, stellarators, heliac and others) as well as in tokamaks. The turbulence causes not only quantitative features of transport but also qualitative ones. Transport dynamics reveals such qualitative features of transport. Various transient transport phenomena observed in helical plasmas indicate complexities of turbulent transport. Recent theoretical works on drift wave turbulence show drift waves are strongly coupled with micro-scale, meso-scale and macro-scale waves. These non-linear couplings form turbulent structures, which have strong influences on transport. Thus, the dynamics and the multi-scale coupling of drift waves are now the most important issues to be clarified in transport studies. A comprehensive understanding of transport dynamics through first principle turbulence models is strongly required for achieving predictive capability of turbulence transport. To study the heat transport dynamics, the transient experiments were performed in the large helical device (LHD). Dynamic transport analysis indicated a complex relationship between heat flux and temperature gradient in LHD. Moreover, an abrupt response of core temperature to an edge perturbation and a long correlation between the core heat flux and the edge temperature gradient were observed. These indicated a presence of non-local transport in helical plasmas. The non-local transport was also observed in tokamaks, and thus the non-locality is considered to be a common feature of turbulence transport in toroidal plasmas. To study the multi-scale coupling of turbulence, experimental observation of spatiotemporal structure of turbulence is essential, therefore, precise fluctuation measurements with multi-Langmuir probes were performed in the large mirror device upgrade (LMD-U). Typical experimental parameters in LMD-U were as follows: an axial length of 3.74m, a plasma radius of 6cm, a magnetic field of <0.15T, central density of 1x1019m-3 and central electron temperature of 3-4eV. New turbulence analysis method based on bi-spectrum and envelope were developed and applied to the probe data. Non-linear interactions between three waves (f1+f2=f3, k1+k2=k3, where f is mode frequency and k is poroidal wave number, respectively) were determined and thus a presence of the multi-scale coupling of drift wave was clarified..
  • Dynamics of Structure Formation in Turbulent Plasma
    keyword : plasma transport turbulence structure
    2007.02~2009.03Turbulence transport is higher than the neoclassical level in the edge to intermediate region in helical devices (heliotron, stellarators, heliac and others) as well as in tokamaks. The turbulence causes not only quantitative features of transport but also qualitative ones. Transport dynamics reveals such qualitative features of transport. Various transient transport phenomena observed in helical plasmas indicate complexities of turbulent transport. Recent theoretical works on drift wave turbulence show drift waves are strongly coupled with micro-scale, meso-scale and macro-scale waves. These non-linear couplings form turbulent structures, which have strong influences on transport. Thus, the dynamics and the multi-scale coupling of drift waves are now the most important issues to be clarified in transport studies. A comprehensive understanding of transport dynamics through first principle turbulence models is strongly required for achieving predictive capability of turbulence transport. To study the heat transport dynamics, the transient experiments were performed in the large helical device (LHD). Dynamic transport analysis indicated a complex relationship between heat flux and temperature gradient in LHD. Moreover, an abrupt response of core temperature to an edge perturbation and a long correlation between the core heat flux and the edge temperature gradient were observed. These indicated a presence of non-local transport in helical plasmas. The non-local transport was also observed in tokamaks, and thus the non-locality is considered to be a common feature of turbulence transport in toroidal plasmas. To study the multi-scale coupling of turbulence, experimental observation of spatiotemporal structure of turbulence is essential, therefore, precise fluctuation measurements with multi-Langmuir probes were performed in the large mirror device upgrade (LMD-U). Typical experimental parameters in LMD-U were as follows: an axial length of 3.74m, a plasma radius of 6cm, a magnetic field of <0.15T, central density of 1x1019m-3 and central electron temperature of 3-4eV. New turbulence analysis method based on bi-spectrum and envelope were developed and applied to the probe data. Non-linear interactions between three waves (f1+f2=f3, k1+k2=k3, where f is mode frequency and k is poroidal wave number, respectively) were determined and thus a presence of the multi-scale coupling of drift wave was clarified..
Current and Past Project
  • We try to observe a topological bifurcation of magnetic field structure in LHD plasma. And we try to develop a method which can measure the statistical features of turbulent plasmas.
  • We try to measure the ion temperature fluctuation by ion sensitive probes. We also try to estimate the fluctuation-driven transport.
  • Plasma turbulence forms spatiotemporal structures, which has analogy with phase. Thus, we aim to draw a phase diagram of plasma turbulence and to observe the transitions near the boundary of phases.
  • To control and to predict the properties of the magnetically confined plasmas, the worldwide researches have been vitally carried out toward realizing a burning plasma in International Tokamak Experimental Reactor (ITER). According to the recent achievement, the new concept is being established that the mesoscale fluctuating structure such as zonal flows and streamers coexist with micro-scale fluctuations, so as to regulate the turbulent transport. The new concept makes it enable to explain the changes in structure and transport occurring in much faster time scale than diffusive one. It is necessary to manage the dynamic changes in transport for control the burning plasma state, thus, the understanding of dynamic transport response should be mandatory. The purposes of this projects are i) to complete the paradigm shift from linear, local, deterministic view to nonlinear, non-local, probabilistic one, ii) to develop and advance the physics of turbulent plasma iii) to understand the mode dynamics and nonlocal transport phenomena, and iv) to clarify the dynamic transport phenomena in the magnetically confined plasmas to provide a concrete base to control the burning plasma in ITER.
  • Structural Formation and Selection Rules in Turbulent plasmas
Academic Activities
Papers
1. S. Inagaki, T. Tokuzawa, K. Itoh, K. Ida, S.-I. Itoh, N. Tamura, S. Sakakibara, N. Kasuya, A. Fujisawa, S. Kubo, T. Shimozuma, T. Ido, S. Nishimura, H. Arakawa, T. Kobayashi, K. Tanaka, Y. Nagayama, K. Kawahata, S. Sudo, H. Yamada, A. Komori, and LHD Experiment Group, Observation of Long-Distance Radial Correlation in Toroidal Plasma Turbulence, Phys. Rev. Lett., 10.1103/PhysRevLett.107.115001, 107.0, 1115001, 2011.09.
2. S. Inagaki, H. Takenaga, K. Ida, A. Isayama, N. Tamura, T. Takizuka, T. Shimozuma, Y. Kamada, S. Kubo, Y. Miura, Y. Nagayama, K. Kawahata, S. Sudo, K. Ohkubo, LHD Experimental group and the JT-60 Team, Comparison of transient electron heat transport in LHD helical and JT-60U tokamak plasmas, Nucl. Fusion , 46 No. 1 133-141, 2006.01.
Presentations
1. Radial Interaction in Dynamic Heat Transport of LHD Plasmas.
Membership in Academic Society
  • The Physical Society of Japan
  • The Japan Society of plasma Science and Nuclear Fusion Research
Awards
  • Transport study on toroidal plasma using dynamic transport analysis
  • Observation of turbulence structures and bifurcation phenomena in linear and torus plasmas
  • Non-Linearity and Non-Locality of Electron Heat Transport in the Helical Plasma
Educational
Educational Activities
Training for plasma experiment and turbulence analysis using the linear magnetized plasma device.
Lecture on basic physical mathematics, basic electrical science and engineering and basic vacuum science and engineering.
Organize international concentrate lectures.