Finite-orbit-width effects on the geodesic acoustic mode in the toroidally rotating tokamak plasma

The Landau damping of geodesic acoustic mode (GAM) in a torodial rotating tokamak plasma is analytically investigated by taking into account the finite-orbit-width (FOW) resonance effect to the 3rd order. The analytical result is shown to agree well with the numerical solution. The dependence of the damping rate on the toroidal Mach number $M$ relies on $k_r \rho_i$. For sufficiently small $k_r \rho_i$, the damping rate monotonically decreases with $M$. For relatively large $k_r \rho_i$, the damping rate increases with $M$ until approaching the maximum and then decreases with $M$.