ECCD EXPERIMENTS IN STELLARATOR/HELIOTRON
This work is partly supported by NIFS/NINS under the NIFS Collaborative Research Program (NIFS04KUHL005) and under a project sponsored by the Formation of International Network for Scientific Collaborations.
Electron cyclotron current drive (ECCD) experiments have been made in stellarator/heliotron (S/H) devices including Heliotron J, TJ-II, CHS and LHD. The experimental results show that ECCD can be controlled by the power injection angle, absorption position and magnetic field structure. The current drive efficiency is similar, γ = neIECR/PEC = 8-16 × 1016 A/Wm2, ζ = 32.7ncIECR/PWTe = 0.03-0.05 when the magnetic field ripple ratio is 0.93 < Bmin/Bmax < 1.0. The reversal of driven current direction is observed depending on the magnetic field ripple structure, indicating that the amplitude and direction of EC current is determined by the balance between the Fisch-Boozer effect and the Ohkawa effect. The toroidal current can be controlled by ECCD; zero net current is demonstrated by cancelling the bootstrap current, and the EC driven current is balanced by co and ctr-ECCD.
