CURRENT-SHEET FORMATION IN 2-DIMENSIONAL CORONAL FIELDS

The formation of current sheets by shearing motions in line-tied twin- lobed fields is examined. A general analytic argument shows that curre nt sheets form along the fieldline bounding the two lobes in the case of both symmetric and asymmetric footpoint motions. In the case of str ictly antisymmetric motions however no current sheets can form. These findings are reinforced by magnetic relaxation experiments involving s heared two-lobed fields represented by Clebsh variables. It is pointed out that, although current singularities cannot be expected to form w hen the line-tying assumption is relaxed, the two-lobed geometry is st ill consistent with the formation of highly localised currents - and s trong resistive dissipation - along field lines close to the bounding fieldline.