Neoclassical tearing modes (NTM) can be responsible for beta limitation in long-pulse ITER discharges. The excitation and growth of NTM are governed by the competing bootstrap current, polarization current and so-called ' ∆ effects. Also, the magnetic well and Electron Cyclotron Current Drive (ECCD) can stabilize the NTM. We study analytically and numerically all the effects with a particular emphasis on the polarization current in the analytical part of our study. We show that the polarization current description requires a generalized transport theory including the hyperviscosity, electron pressure gradient and, as well, the finite ion Larmor radius effects in the perpendicular current. The profile function nonstationarity must be taken into account for calculation of the island rotation frequency. Results of numerical simulation of NTM suppression by modulated ECCD in ITER are presented.

The effect of a transverse magnetic field on a toroidal discharge in a strong longitudinal magnetic field was studied. It was found that, for a definite value of the pinch displacement caused by the 1/c [I,B⊥], force, the oscillations on the oscillograms of the electrical characteristics of the discharge had minimum amplitude, while the mean plasma conductivity reached a maximum. It was shown that the effect of the transverse component of the magnetic field could, in general, be explained from the concept of the equilibrium of the plasma pinch inside the conducting sheath.