Evolution of magnetic field structure and particle acceleration in solar flares Original Research Article

We present hard X-ray imaging observations of impulsive solar flares with Yohkoh HXT, focusing on the evolution of hard X-ray double footpoint sources seen in the energy range above 30 keV. In 7 out of the 14 events studied, the separation between the double sources increases (at the 3σ confidence level) as the flare progresses, with the double sources moving nearly anti-parallel to each other in most cases. Implications of these results to the global magnetic field structure responsible for solar flare energy release / particle acceleration are discussed.