  We report on investigations of mode coupling between rotating spokes during
the onset of the breathing oscillation. Demonstrating the existence of
nonlinear coupling between the sporadic spokes and the breathing oscillation,
we suggest the oscillating azimuthal electric field as the energy source for
additional ionization within the plasma. Our results indicate that intermittent
three-wave coupling is a possible mechanism for triggering low-frequency
breathing oscillations in partially magnetized cross-field plasma.
