Interaction between high-frequency turbulence and magnetospheric micropulsations

Abstract

The quasi-linear interaction between a high-frequency whistler noise and a drift wave is considered as a possible explanation of the miropulsations observed during the magnetospheric substorms. The drift wave is a so-called ion trapped mode that propagates in a direction almost perpendicular to the magnetic field and has a frequency lower than the ion bounce frequency. Plasma pressure and field line curvature are taken into account in the general frame of the Vlasov equation. The drift wave interacts with the high-frequency turbulence by inducing anisotropy in the electron distribution function. As an example, growth rates and polarizations are computed for frequencies in the range of the Pc 5 micropulsations and compared to the observations. (auth)