Electromagnetic geodesic acoustic modes are analytically investigated in tokamak plasmas with anisotropy, utilizing gyro-kinetic equations and a rigorously self-consistent anisotropic distribution. When including first-order finite-orbit-width effects and first-order finite-Larmor-radius effects, it is proven that the anisotropy with an arbitrary strength does not induce the harmonics of , where m and denote the poloidal wavenumber and the parallel component of the perturbed magnetic vector potential, respectively. The rigorously self-consistent anisotropy introduces an equilibrium electrostatic field with poloidally asymmetric structure, and consequently induces an additional drift term within the gyro-kinetic equation. This equilibrium electrostatic field inhibits the anisotropy from generating non-zero harmonics of . Indeed we demonstrate that introducing anisotropy self-consistently into the equilibrium quantitatively influences harmonics of the perturbed electrostatic potential, but only the harmonics of .
This paper analyzes how electromagnetic waves affect the behavior of geodesic acoustic modes in tokamak plasmas with anisotropy. It shows that the anisotropy does not create additional harmonics of the perturbed magnetic field, but it does influence the harmonics of the perturbed electrostatic potential.