Speaker
Fumiyoshi Kin
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.4009.pdf
Nonlinear characteristics of mediator and streamer in linear magnetized
plasmas
F. Kin1 , A. Fujisawa2,3 , K. Itoh3,4,5 , Y. Kosuga2,3 , M. Sasaki2,3 , T. Yamada3,6 ,
S. Inagaki2,3 , S.-I. Itoh2,3,7 , T. Kobayashi5 , Y. Nagashima2,3 , N. Kasuya2,3 ,
H. Arakawa8 , K. Yamasaki2 , K. Hasamada1
1 Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga,
Japan
2 Research Institute for Applied Mechanics, Kyushu University, Kasuga, Japan
3 Research Center for Plasma Turbulence, Kyushu University, Kasuga, Japan
4 Institute of Science and Technology Research, Chubu University, Aichi, Japan
5 National Institute for Fusion Science, Toki, Japan
6 Faculty of Arts and Science, Kyushu University, Fukuoka, Japan
7 Department of Innovative Energy Science and Engineering, Graduate School of Engineering,
Chubu University, Aichi, Japan
8 Teikyo University, Omuta, Japan
In magnetized plasmas, drift waves are excited by inhomogeneity of the pressure gradient and
can develop into nonlinear structures, such as zonal flow and streamer. The study of these non-
linearly evolved structures are important for nuclear fusion, since they affect radial transport and
determine confinement. One of the cause of anomalous transport is due to the streamer, which is
known as radially elongated and azimuthally localized structure. In a linear device, LMD-U in
Kyushu University, streamer was found to be excited by the modulation of drift waves through
low frequency fluctuations, namely mediator [1].
Up to date, the mediator has been simply treated as linear wave. However, by applying the
conditional averaging, the mediator is found nonlinear wave that contains harmonic compo-
nents excited from the self-couplings in the PANTA, the successor device of the LMD-U.
Moreover, the envelope of the streamer also contains higher harmonic components of which
frequencies are identical to that of the mediator. This indicates that the streamer should be mod-
ulated through higher harmonic components of the mediator as well as through fundamental
components. Furthermore, it is also found, as is commonly observed for solitons, that the am-
plitude of the co-existing solitary structures, mediator and streamer, increase inversely with the
square of the width of half maximum.
References
[1] T. Yamada et al. Nature Phys. 4, 721 (2008)
