Results from stabilization of neoclassical tearing modes(NTMs)in JT-60U are de-scribed.NTM stabilization and confinement improvement have been demonstrated by employinga real-time NTM stabilization system,where the identification of the location of an NTM andthe optimization of the injection angle of the electron cyclotron wave are performed in real time.Also,a high-beta plasma with the normalized beta of 3 has been sustained by suppressing NTMby applying the electron cyclotron current drive(ECCD)before the onset(‘preemptive ECCD’).In addition,a simulation code for analysis of the NTM evolution has been developed by combiningthe modified Rutherford equation with the transport code TOPICS.It is found that the simulationwell reproduces the NTM behavior in JT-60U.The simulation also shows that the ECCD widthis also important for NTM stabilization,and that the EC wave power for complete stabilizationcan be reduced by narrowing the ECCD profile.
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