Dissipation of hydromagnetic waves in the viscous polytropic zone of the solar wind including FLR corrections, ohmic diffusion, and the Hall effect

Abstract

ABSTRACT In the polytropic zone of the solar wind, we have used the generalized polytrope pressure laws to investigate the dissipation of hydromagnetic waves and pressure-anisotropy-driven fluid instabilities in magnetized viscous plasmas, including finite Larmor radius (FLR) corrections and non-ideal magnetohydrodynamic (MHD) effects. The modified dispersion properties have been analysed in the MHD and Chew–Goldberger–Low (CGL) limits for typical conditions of the solar wind and corona. The theoretical results are found to be in good agreement with the observational data, which shows that the MHD and CGL waves are dissipated due to viscous and ohmic diffusion. The FLR and Hall parameters show destabilizing and stabilizing influences, respectively, for the strong magnetic fields in the solar corona, and reversed effects in the case of weak magnetic fields in the solar wind. In the solar corona, the CGL wave dissipation achieves the required damping rate in the minimum time than the dissipation of the MHD waves. The damping time is mainly associated with the considered parameters and was found to be larger for the MHD wave dissipation than the CGL wave dissipation. The theoretical results successfully demonstrate the role of the considered parameters on the reverse and forward shock waves and instabilities as observed in the solar wind parameters versus heliolatitude graph using Ulysses observations for r = 5.41 au. The results are helpful to explore the possibilities of MHD waves and pressure-anisotropy-driven fluid instabilities in the polytropic zone of the solar wind that will probably be observed by the Parker Solar Probe (PSP) mission.