Experimental observation of phase-flip transitions in two inductively coupled glow discharge plasmas

Synchronization of dust acoustic waves in a forced Korteweg-de Vries-Burgers model

The synchronization of dust acoustic waves to an external periodic source is studied in the framework of a driven Korteweg-de Vries-Burgers equation that takes into account the appropriate nonlinear and dispersive nature of low-frequency waves in a dusty plasma medium. For a spatiotemporally varying source term, the system is shown to demonstrate harmonic (1:1) and superharmonic (1:2) synchronized states. The existence domains of these states are delineated in the form of Arnold tongue diagrams in the parametric space of the forcing amplitude and forcing frequency and their resemblance to some past experimental results is discussed.

Phase switching phenomenon in a system of three coupled DC glow discharge plasmas

We report the first experimental observations of phase switching in a system of three coupled plasma sources. Two of the plasma sources are inductively coupled to each other while the third one is directly coupled to one of them. The coupled system acquires a frequency pulling synchronized state following which a transition occurs to a frequency entrainment state with an increase in the frequency of the directly coupled system. We also observe a sudden jump from a lower to a higher frequency entrainment state and a concomitant phase switching between the oscillations of the two directly coupled sources while the phase difference between the inductively coupled sources remains constant. These experimental findings are established using various diagnostic tools, such as the Fourier spectra, frequency bifurcation plots, Lissajous plots, and Hilbert transforms of the data. The experimental results are qualitatively modeled using three coupled van der Pol equations, in which two of them are environmentally coupled while the third one is directly coupled with one of them.