2013 Volume 8 Pages 2401148
Magnetic energy injection through pull magnetic reconnection has been studied in the University of Tokyo Spherical Tokamak (UTST) using external poloidal field coils. Under constant plasma inflow, the magnetic energy of the produced ST increases as the guide field Bt is increased from zero to the optimized value Bt0, while it decreases after Bt exceeds Bt0. The pull reconnection process was often accompanied by the formation of plasmoids around the X-point. The reconnection rate was found to change with time, depending on the formation of plasmoids and the magnetic energy injection. Plamoids enhance the reconnection rate.