Magnetosonic wave propagation in the mode conversion regime

The propagation of the fast magnetosonic wave is studied, taking into account the effect of the two-ion hybrid layer. Using a one-dimensional model, which includes density and magnetic field gradients, the wave equation is solved in the cold plasma approximation. The existence of radial eigenmodes confined between the two-ion hybrid layer and the low field side wall is predicted. Comparison with experimental data obtained on the TFR tokamak confirms the theoretical conclusions. Toroidal eigenmodes are observed even in the mode conversion regime when the antenna is on the low magnetic field side. (author)