Symmetry breaking induced by the parity change in global electromagnetic ion temperature gradient modes

We perform a computational study of the effects of finite plasma beta(=plasma thermal energy/magnetic energy) on the residual stress in the context of the quasi-linear theory. The five-field electromagnetic (EM) toroidal ion temperature gradient (ITG) model is considered in the realistic tokamak geometry. Analyses show that the residual stress significantly increases and its radial profile changes from a dipolar to a unipolar shape with increasing beta. The change in the mode parity is found to be responsible for the enhancement and the profile change of the residual stress driven by the global EM toroidal ITG mode. This finding highlights the importance of the global eigenmode structure in determining the radial profile of the residual stress. Published by AIP Publishing.