Azimuthal surface waves at the plasma-metal boundary in a nonuniform toroidal magnetic field

The propagation of electromagnetic surface waves with extraordinary polarization across the circular axis of a metal ring in a magnetized plasma is studied using perturbation theory. The amplitude of the fundamental mode of these waves is determined to within second-order terms, and the amplitudes of the nearest satellite modes are found correct to first-order terms. The correction to the eigenfrequency that comes from the nonuniformity of a constant toroidal magnetic field is shown be a second-order quantity.