QUADRUPOLAR FORCE-FREE MAGNETIC-FIELDS WITH SINGULAR CURRENT-DENSITY SURFACES

This paper derives analytical solutions for localized quadrupolar forc e-free magnetic fields with singular current density surfaces as well as magnetostatic equilibria with similar magnetic configurations. The singular current density surfaces are proved to be stable against idea l magnetohydrodynamic perturbations. It is suggested that the resistiv e dissipation creates merely a slow magnetic diffusion and spreads a s ingular current density surface into a thin layer of high electric cur rent density. Therefore, a singular current density surface will devel op in a highly sheared force-free held and persist for a long time. Th e relevance of the results to the solar flare energy release is discus sed.