Spatial structure and dispersion of drift mirror waves coupled with Alfvén waves in a 1-D inhomogeneous plasma

摘要

The paper employs the frame of a 1-D inhomogeneous model of space plasma,to examine the spatialstructure and growth rate of drift mirror modes, often suggested for interpreting some oscillation types in spaceplasma. Owing to its coupling with the Alfvén mode, the drift mirror mode attains dispersion across magneticshells (dependence of the frequency on the wave-vector's radial component, k_r). The spatial structure of a modeconfined across magnetic shells is studied. The scale of spatial localization of the wave is shown to bedetermined by the plasma inhomogeneity scale and by the azimuthal component of the wave vector. The wavepropagates across magnetic shells, its amplitude modulated along the radial coordinate by the Gauss function.Coupling with the Alfvén mode strongly influences the growth rate of the drift mirror instability. The mirror modecan only exist in a narrow range of parameters. In the general case, the mode represents an Alfvén wavemodified by plasma inhomogeneity.