Nonlinear study of transition modes in the chaotic time series obtained in different negative differential resistance regimes

Introducing a biased grid between an asymmetrical electrode system significantly influences plasma dynamics by controlling charged particle flux in the presence of an ambient magnetic field. Selective biasing facilitates the axial transport of energetic electrons through the grid, evidently supported by the rise in discharge current along with the emergence of negative differential resistance (NDR). The trapping of low energetic electrons near the biased grid and subsequent diffusion of nonthermal electrons toward the anode momentarily characterize the NDR formation and generate burst oscillations. The presence of NDR and its resilience to withstand associated instabilities demands further investigation of discharge transition to chaos using the empirical mode decomposition technique. The power spectrum analysis and the estimation of the largest Lyapunov exponent are concurrently used to verify the presence of complexity and the transition of periodicity into chaos. Multiple coherent modes, represented by the intrinsic mode function, carry most of the energies during the discharge in the presence of sheath–plasma instability, confirming the transition of multiple dominant modes from periodic to chaotic discharge regimes due to the intermittent behavior of the burst oscillations in the system.