Abstract
An analytic study is conducted on the impact of poloidal E×B flow on geodesic acoustic mode (GAM) in the edge pedestal of a tokamak plasma. A set of coupled nonlinear equations is derived from a reduced magnetohydrodynamic model. Analytic solutions to the set of coupled equations reveal that the non-geodesic component of a poloidally asymmetric pressure perturbation begins to contribute to GAM when the E×B flow is accounted for in the analysis. The full nonlinear solution shows that the sinusoidal GAM oscillation changes into the cnoidal one which is represented by the Jacobi elliptic function. The GAM frequency increases in proportion to the initial radial electric field (Er). The potential impact of this pedestal Er oscillation on the transport process in the externally perturbed edge transport barrier is discussed.
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