Coronal Loops

Abstract

The statistical treatment of the magnetohydrodynamically turbulent plasma is used to study the steady state configuration of the coronal loops. The stability of the plasma system is defined in terms of certain invariants like total energy, magnetic helicity and magnetic fluxes. The steady state is represented by a superposition of two Chandrasekhar-Kendall functions. This representation defines the three dimensional temperature structure of the coronal loops. We present only two dimensional (r,z) variation of temperature in a cylindrical geometry of the loop. The radial as well as the axial variation of the temperature in a constant density loops is calculated. These variations are found to conform to the observed features of cool core and hot sheath of the loops as well as to the location of the temperature maximum at the apex of the loop. We find that these features are not present uniformly all along either the length of the loop or across the radius. We further study the nature of and relationship between the velocity field and magnetic field flutuations using the nonlinear MHD equations and the statistical description of MHD turbulence. It is found that these fluctuations are of Alfvenic type. A possible existence of Alfven waves with group velocity along and opposite to the average magnetic field is shown. This study has important bearing on the heating mechanism of coronal loops.