Magnetic Field Annihilation

Sweet's mechanism for the rate of annihilation of magnetic field at the boundary between two regions of plasma containing oppositely directed field lines is re-examined. It is pointed out that previous analyses overlooked standing magnetohydrodynamic waves as a possible mechanism for converting magnetic energy to plasma energy. An estimate of the annihilation rate including such waves is made. Using this rate it is found that the energy required for a flare can be released in 100 sec. This time is short enough to account for the observed solar flare times if the source of the flare energy is stored magnetic energy. (Author)