Stabilization of Neoclassical Tearing Mode by ECCD for JT-60 Superconducting Tokamak
Nobuhiko Hayashi, Takahisa Ozeki, Kiyotaka Hamamatsu and Tomonori Takizuka
Japan Atomic Energy Research Institute, Ibaraki, 311-0193, Japan
Abstract.
Stabilization of the neoclassical tearing mode (NTM) by an electron cyclotron current drive (ECCD) in JT-60 superconducting tokamak is performed by using a time-dependent simulation model based on the modified Rutherford equation, the plasma transport equations, the current diffusion equation and the EC code. A local EC current on the center of the island can fully stabilize NTM. Off-center EC current can decrease the island width, but not fully stabilize NTM. EC current moves the rational surface through the background current profile modification and decreases the stabilizing efficiency of EC. Conditions of the full stabilization is investigated for various EC powers, current locations and profiles. Low power and peaked current profile are effective in the full stabilization. When detecting the island center is difficult, high power and broad current profile are effective.