Sherwood 2015

Abstract Details

files Add files

Parameter dependence of two-fluid and finite Larmor radius effects on Rayleigh-Taylor and Kelvin-Helmholtz instabilities in finite beta plasmas

Author: Atsushi Ito
Requested Type: Poster Only
Submitted: 2015-01-19 08:42:02

Co-authors: R.Goto, T.Hatori, H.Miura, M.Sato

Contact Info:
National Institute for Fusion Science
322-6 Oroshi-cho
Toki, Gifu   509-529

Abstract Text:
The parameter dependence of two-fluid and ion finite Larmor radius (FLR) effects on the Rayleigh-Taylor (RT) and Kelvin-Helmholtz (KH) instabilities in magnetized, finite beta plasmas are studied by using extended magnetohydrodynamic (MHD) equations. It is known that large wavenumber modes of RT-type instabilities are completely stabilized due to these small scale effects [1]. Recent studies based on extended MHD equations [2-5] show that the growth rate indicates more complicated behavior depending on parameters than the conventional theory [1] when plasma beta is finite. In our recent nonlinear extended MHD simulation results, the secondary KH instability is found in the nonlinear stage of RT instability when both of two-fluid and FLR effects are included and the amplitude depends on the direction of flow shear compared with that of the pressure gradient that causes the diamagnetic drifts arising due to these effects [5]. The real frequencies of RT and KH modes are modified by diamagnetic drifts. In this study, we examine, by linear stability analysis, the effects of two-fluid and FLR on the RT and KH instabilities in a wide range of parameters, such as the pressure and density gradients, beta value and wavenumber, to clarify the complicated behavior of the stabilization and diamagnetic drift effects. The large wavenumber modes of the RT instability@are investigated by solving local dispersion relation while the small wave number modes of the RT instability and the all modes of KH instability are studied by solving the eigenmode equations. The results are compared with our nonlinear extended MHD simulations.

[1] K. V. Roberts and J. B. Taylor, Phys. Rev. Lett. 8 (1962) 197.
[2] P. Zhu et al., Phys. Rev. Lett. 101, 085005 (2008).
[3] P. W. Xi et al., Nucl. Fusion 53, 113020 (2013).
[4] R. Goto, H. Miura, A. Ito, M. Sato and T. Hatori, Plasma Fusion Res. 9, 1403076 (2014).
[5] R. Goto, H. Miura, A. Ito, M. Sato and T. Hatori, submitted to Phys. Plasmas.


March 16-18, 2015
The Courant Institute, New York University