Contours of dimensionless axial current, j_z, in the mid-plane at z = 0. The kink instability is characterized by the formation of a crescent of strong current, as is apparent in panel a. The times shown are the time at which the initial kink instability is seen (panel a), the time of disruption of the right-hand thread (panel b), the time of disruption of the left-hand thread (panel c), and a general time showing the large number of strong current layers (panel d). Where the magnitude of current exceeds j_crit. = 5.0, resistivity istriggered.