Gyrokinetic simulations of influence of electron cyclotron current drive on neoclassical tearing mode in tokamaks*

GTC gyrokinetic simulations of the influence of electron cyclotron current drive (ECCD) and ion kinetic effect on the neoclassical tearing mode (NTM) in HL-2A configurations have been carried out. The bootstrap current is included with a simple fluid model. We compared the results of the GTC NTM calculations with those of the fluid code, tm8. Effects of ECCD on NTM have also been investigated. It is found that a helicon current drive which is in the same phase as magnetic island o-point is more efficient than a continuous ECCD. Analysis of the GTC simulation reveals that the thermal ion kinetic effects can reduce the island width as well as the growth rate. Finally, the kinetic effects of thermal ions on NTM is found to be more pronounced with higher ion temperature.