Alfvén wave driven compressional fluctuations in shear flows

Abstract

The nature of driven linear compressible fluctuations is studied when there is an Alfvén wave propagating in the medium characterized by an inhomogeneous velocity field. This Brief Communication is an extension of our recent study [E. Kh. Kaghashvili et al., Phys. Plasmas 13, 112107 (2006)] in which analytical solutions were presented revealing a nature of driven compressional waves accurately in a low β-plasma. Here, this assumption is removed and analytical solutions that accurately describe compressional waves in the general case are obtained. While the solutions of the driven waves in a long run follow the WKB description, the main goal here is to study an initiation and evolution of compressible disturbances at earlier times. The purpose of this Brief Communication is to derive the formal solutions for compressional fluctuations driven by the initial Alfénic spectrum.