An optimization approach to reconstructing force-free fields

A new method for reconstructing force-free magnetic fields from their bound ary values, based on minimizing the global departure of an initial held fro m a force-free and solenoidal state, is presented. The method is tested by application to a known nonlinear solution. We discuss the obstacles to be o vercome in the application of this method to the solar case: the reconstruc tion of force-free fields in the corona from measurements of the vector mag netic held in the low atmosphere.