Dependence of Toroidal Current on Bumpy Field Component in Heliotron J

Toroidal current has been studied in electron cyclotron heating (ECH) and ECH + neutral beam injection (NBI) plasmas on Heliotron J by controlling the bumpy field component. In the ECH plasma with high density, the toroidal current increases from 0.3 to 1.5 kA when B-04/B-00 is increasedfrom 0.01 to 0.15, where B-04 and B-00 are the bumpy field and the uniform field components, respectively. The observed toroidal current is qualitatively in good agreement with neoclassical calculation results without radial electric field except for a low bumpy configuration case at low density. If the radial electric field is responsible for the deviation in the low bumpiness case, the central electric potential is estimated to be similar to 3 to 5 kV The dependence of the net toroidal current on the bumpiness has also been observed in the ECH + NBI plasma. An estimation of the Ohkawa current has been attempted.