Magnetic island dynamics in magnetic reconnection in UTST experiments

The dynamics of the magnetic island formed inside the reconnection current layer was investigated under the strong guide field in the UTST spherical tokamak merging experiment. A pair of proximately located O- and X-points was generated at similar to 5 cm away from the other X-point. The formed O- and X-points immediately started to move toward the downstream region inside the current layer, but the O-point had larger velocity and caught up the preceding X-point within 0.5 mu s. The results from Doppler spectroscopy indicated that the ion flow velocity had the intermediate value between the O- and X-point velocities, suggesting that the ions flowed with approximately the same velocity with the magnetic island. Published by AIP Publishing.