THE MAGNETIC FIELD AND FLARES OF GREAT SUNSPOT GROOP IN LATE APRIL,1978

Five day's magnetic field isogaussgrams of the active region assigned the Yunnan Observatory Serial Number 78126 are presented.lt seems that the reversed magnetic polarity arrangement and the neutral line of longitude field changing to more twisted are close correlated to energetic proton flare explosion.After the occurrence of flares either the arrangement of magnetic polarity or the neutral line of the longitude field tends to a relatively stable state.We find that Φ,the net magnetic flux of the region,had rapid changes during 28-30 th April in 1978 and two huge flares occurred at the same period.We suggest that the powerful electromotive force caused by the rapid changes of the magnetic flux created the conditions of acceleration of electrons and protons.After analysing the distribution of the flare knots in the magnetic field we find that most of the bright flare knots of the active region are far away from the neutral line region.The bright knots near the neutral line may be roughly divided into two situations,one is in the region with large magnetic field gradient and countercurrent density on either side of the neutral line,the other is near "the neutral points" of the field.