The instability observed in the CTCC-I spheromak plasma

In the CTCC-I experiment, the instability appears in almost all the discharges and occurs several times in the every discharge. The dominant toroidal mode number for this instability is the n = 2, which is measured using a toroidally arrayed magnetic probe. This mode shows different behavior in the instabilities; in the earlier and intermediate phase of the discharge the saturation phase come to appear, but near the termination this saturation phase does not appear. These phenomena probably depend on the magnetic Reynolds number. The evolution of the magnetic field configuration is also investigated. From these results, the instability observed in the CTCC-I spheromak is found to be the n = 2 ideal kink mode. (author)