Periodic nonlinear wave–wave interaction in a plasma discharge with no external oscillatory driving force

Experimental measurements of time series and frequency spectra characterize a periodic nonlinear interaction between pairs of self-excited, propagating, ionization waves simultaneously present in the positive column of a neon glow discharge. No periodically varying external driving force is applied. The interaction is the spatio-temporal extension of the previously established temporal periodic pulling process, the incomplete entrainment of a driven nonlinear oscillator. The particular mode playing the role of the driving perturbation in the interaction can be selected and is identified by inspection of the asymmetric, multisideband spectrum of light fluctuations, which reflect the system’s dynamics. A comparison between the spatio-temporal and temporal periodic pulling shows that the former is associated with a relatively strong driving force.