Triggering of Neoclassical Tearing Mode by Error Field Penetration

抄録

We conduct the first simulation study of the neoclassical tearing mode (NTM) triggered by error field penetration. A series of processes including the error field penetration, formation of seed islands, and the triggering of the NTM occurs, when the plasma flow and the electron diamagnetic drift approximately cancel out each other. The excited NTM is the born-locked mode, which is locked from the beginning. In the case where the plasma flow and the electron diamagnetic drift completely cancel out each other, a vacuum island width necessary for triggering the born-locked NTM is much smaller than a seed island width necessary for triggering the original NTM. This tendency is consistent with a theoretical prediction. Thus, whether the born-locked NTM is excited depends on both the plasma flow velocity and the error field amplitude.