Characteristics of localized resonance coupling oscillations of the slow magnetosonic wave in a non-uniform plasma

Abstract

We analyze linear resonance oscillations in a non-uniform one-fluid finite-β plasma, which is oversimplified to understand easily fundamental characteristics of the resonance oscillations. A linear resonance oscillation of localized slow magnetosonic mode [ω 2 s = ω 2 A (1 + V 2 A V 2 s ) ] , which has the diamagnetic property in a uniform plasma, is newly found to be excited in the radially non-uniform plasma. The localized slow resonance indicates a radially polarized compressional oscillation ( δB ∥ ≳ δB H ⪢ δB D ). The sense of the Alfvénic polarizations in the H- D plane near the resonant point is a function of both the propagation in the azimuthal direction and the slope of wave amplitude in the radial direction, whereas the sense of the resonant slow magnetosonic polarizations changes in accordance only with the switch in the azimuthal propagation direction. Further multi-satellite studies are necessary to establish the resonant structures of the slow magnetosonic waves in the magnetosphere.