The Formation of a Magnetic Channel by Emergence of Current-Carrying Magnetic Fields

The term magnetic channel indicates a series of polarity reversals separating elongated flux threads with opposite polarities. We studied the formation process of the magnetic channel in AR 10930 using time sequence SP data taken by SOT/Hinode. As a result, we detected both upflows (-0.5 to -1.0 km s(-1)) and downflows (+1.5 to +2.0 km s(-1)) within the channel site, and a pair of strong vertical current threads of opposite polarity along the channel. We also analyzed coronal magnetic fields computed from the non-linear force-free field extrapolation, and found that the current density in the lower corona increased as the channel structure evolved. These findings support the idea that the magnetic channel represents the emergence of the twisted flux tube.