부산대학교 도서관

This article presents a new model of the North Polar Coronal Hole (NPCH) with the aim of revealing the dissipative/propagative characteristics of magnetohydrodynamic (MHD) waves. We investigate the effects of isotropic viscosity and anisotropic heat conduction on the propagation characteristics of MHD waves in the NPCH. We first model the NPCH by considering differences in the radial direction as well as in the direction perpendicular to the line of sight (los) in temperature, particle number density and non-thermal velocities between plumes and interplume lanes, for the specific case of Ovi ions. This model includes parallel and perpendicular (to the magnetic field) heat conduction and viscous dissipation. Next, we derive the dispersion relations for MHD waves in cases of the absence and presence of parallel heat conduction. in the case of the absence of parallel heat conduction, we find that MHD wave dissipation depends strongly on viscosity for modified acoustic and Alfven waves. The energy flux densities of acoustic waves vary between 104.7 and 107 erg cm-2 s-1, while the energy flux densities of Alfven waves turn out to be between 106 and 108.6 erg cm-2 s-1. When there is parallel heat conduction, we calculate the damping length-scales and the energy flux densities of magnetoacoustic waves. Our results suggest that modified magnetoacoustic waves may provide a significant source for the observed preferential acceleration and heating of O vi ions, thus coronal plasma heating, and an extra accelerating agent for the fast solar wind in the NPCH, depending on the values of the transport coefficients. [ABSTRACT FROM AUTHOR]