Laboratory observation of a nonlinear interaction between shear Alfven waves

An experimental investigation of nonlinear interactions between shear Alfven waves in a laboratory plasma is presented. Two Alfven waves, generated by a resonant cavity, are observed to beat together, driving a pseudomode at the beat frequency. The pseudomode then scatters the Alfven waves, generating a series of sidebands. The observed interaction is very strong, with the normalized amplitude of the driven pseudomode comparable to the normalized magnetic field amplitude (delta B/B) of the interacting Alfven waves.