Frequency shift of long-wavelength modes due to interactions between short-wavelength drift waves

초록

The frequency shift of long-wavelength modes due to interactions between short-wavelength drift waves is studied by using renormalized statistical theory in the Hasegawa-Mima model. Nonlinear interactions affect the modes both coherently by changing the mode characteristics and incoherently by imposing a noise. Although the growth rate has been the main focus, it is equally crucial to understand the phase shift from the linear characteristics. A study of the interactions between the disparate scales of the drift waves is important because it may have important implications in the generation of zonal flows. The test-field model is applied in order to properly treat the sweeping effect of the large scales on a small scale. The frequency shift is found to be small compared to the growth rate, and the nonlocal triad mode-interaction time turns out to be determined by the energy of the long-wavelength modes.

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