Linear force-free fields in the lower corona

Abstract

We have computed the surface Green's function for linear force-free magnetic fields, where ▽ × B = κB and κ is a constant, for application to low coronal levels of the solar atmosphere. Boundary conditions are imposed on the normal component of B on two parallel planes which delineate the force-free volume. This procedure ensures that the magnetic field energy remains bounded, and that the field lines have a smooth behavior. A simple bipolar source distribution is treated and representative field line tracings are shown.