Study of Time Evolution of Toroidal current in LHD

We study the properties of non-inductive current in LHD experiments. The experimentally observed dependence on the plasma stored energy and the magnetic axis position agrees with a theoretical prediction based on bootstrap current under NB balanced injection. We apply a calculation model of time evolution in toroidal current profile based on bootstrap current and Ohkawa current to analyzing the dynamic change of the rotational transform in a discharge with fairly high beta and high positive toroidal current. The numerical analysis suggests that the disappearance of L=ll2 rational surface leads to the sudden disappearance of the m/n=211 magnetic fluctuation experimentally observed.