On the Nonlinear Coupling of the High Wavenumber Fluctuations Exhibiting the Discrete Spectra Observed in PANTA

抄録

We report on the nonlinear coupling properties of high-wavenumber fluctuation, which exhibits discrete frequency spectra with a frequency span comparable to the ion cyclotron frequency observed in PANTA. Bicoherence analysis is used to investigate this nonlinear coupling. The results indicate a finite coupling between individual discrete peaks but no coupling between the ion cyclotron frequency components of these discrete peaks. This suggests that the observed turbulence with a discrete spectrum is destabilized linearly rather than through nonlinear coupling.