Suppression of neoclassical tearing mode instability at the initial stage by electron cyclotron current drive

The suppression of the neoclassical tearing mode (NTM) by the electron cyclotron wave current drive (ECCD) is studied numerically based on the reduced MHD equations. The required current drive for the NTM stabilization is shown to be significantly reduced if ECCD is applied at the initial stage when the magnetic island is not too large. The modulated ECCD is more effective than a continued one to suppress the NTM, as expected. The value of the duty circle of modulated ECCD is also found to affect the result.