On the Constancy of the Width of Coronal Magnetic Loops

Abstract

The variation of the width of coronal current-carrying magnetic loops with height is considered. Two invariants are taken into consideration: conservation of the longitudinal magnetic field flow through the tube cross-section, and conservation of the electric current through the cross-section. It is shown that, if gas kinetic pressure inside the tube is low in comparison with the longitudinal magnetic field pressure, the tube width does not vary with height in the corona, which is typical for most magnetic loops observed in the corona. Otherwise, when the gas kinetic pressure exceeds the longitudinal magnetic field pressure, the tube width increases within the double scale of height of the inhomogeneous atmosphere. The increase in width with height is typical for certain postflare loops that feature higher parameters of temperature and plasma concentration.