Study of Nonlinear Behavior of Low-Frequency MHD Mode Caused by Transition of Radial Electric Field in LHD

摘要

The response of low-frequency magnetic fluctuations in a transition of radial electric field ( E _r) is investigated in the edge region of LHD plasmas. Consequently, the amplitude of a magnetic fluctuation with f ? 2 - 5 kHz is suddenly enhanced at the transition timing of E _r, and then disappeared after the transition of E _r. Furthermore, it is found that the amplitude of H _α signals is enhanced, corresponding to the abrupt diminishing of the magnetic fluctuation with f ? 2 - 5kHz.