Identification of the parametric-modulational instability of the drift wave-zonal flow system in a cylindrical magnetized plasma
POSTER
Abstract
We present observation of the parametric-modulational instability of the drift wave-zonal flow system in the Large Mirror device of Kyushu University. Linear dispersion relations of observed fluctuations are consistent with theoretical predictions of meso-scale residual zonal flow and micro-scale drift-wave. Oscillation of the zonal flow potential is synchronized at modulations of amplitude, radial wavenumber, and turbulence Reynolds stress per mass density of the drift-wave. The bispectral analysis reveals nonlinear energy transfer from the drift-wave into the zonal flow at a radial location where the zonal flow forms a shear structure. Non-local energy transfer to turbulence via ``zonal flow channel'' is also discussed.
*This work was partly supported by the Grant-in-Aid for Specially-Promoted Research (16002005) of MEXT, and by the Grant-in Aid for Young Scientist (B) (18760637) of MEXT, Japan.