Mechanisms of plasma rotation effects on edge magnetohydrodynamic (MHD) stability are investigated numerically by introducing energies that are distinguished by physics. By comparing them, it is found that an edge-localized MHD mode is destabilized by the difference between the eigenmode frequency and the equilibrium toroidal rotation frequency, which is induced by rotation shear. In addition, this destabilizing effect is found to be effective in the shorter wavelength region. The effect of poloidal rotation on the edge MHD stability is also investigated. Under the assumption that the change in equilibrium by poloidal rotation is negligible, it is identified numerically that poloidal rotation can have both stabilizing and destabilizing effects on the edge MHD stability, which depends on the direction of poloidal rotation. A numerical analysis demonstrates that these effects of plasma rotation in both the toroidal and poloidal directions can play important roles in type-I edge-localized mode phenomena in JT-60U H-mode plasmas.
Poloidal rotation of tokamak plasmas at super poloidal sonic speeds