Coexistence of chaotic and complexity dynamics of fluctuations with long-range temporal correlations under typical condition for formation of multiple anodic double layers in DC glow discharge plasma

摘要

Analysis of electrostatic floating potential fluctuations associated with multiple anodic double layer revealed a complexity dynamic coexisting with chaotic behavior. These externally controllable nonequilibrium quasi-stationary multiple anodic double layers were created in a cold cathode dc discharge setup in front of an extra anode which was used to supplement additional ionization. Despite the fact that chaos and complexity dynamics are often defined with entirely different properties, this study provides scenarios under which both can exist simultaneously. A stable multiple double-layer structure consisting of four successive double layers, each with positive and negative charged particles arranged in opposite sheets, was created when the anode potential exceeds a certain threshold value for a minimum gas breakdown bias between cathode and ground. After the stable multiple double layers was created, it was further controlled externally by varying the cathode bias between minimum gas breakdown bias of - 335 V and - 610 V at a pressure of 0.3 mbar for studying its advanced stages. With increase in cathode bias, multiple anodic double-layer structure advances towards the anode surface with the collapse of innermost layer due to the arrival of more energetic electrons in the anode zone. This process results from the self-organization and re-organization of charged particles in each double layer mediated by energetic electrons. The process continued until all the double layers disappeared and only an intense anode glow remained at anode for higher values of cathode bias. The chaotic dynamics of the system was studied at every stage by analyzing the corresponding floating potential fluctuations using FFT, phase space trajectories and nonlinear technique such as Lyapunov exponent, time-delay reconstruction etc. The analysis revealed the onset of chaos beyond - 410 V was triggered by the collapse of double layers. Estimation of correlation dimension, autocorrelation function and Hurst exponent unfolded the complexity features such as self-similarity and longtime dependence in the fluctuations. The value of correlation dimension reaches the maximum with an increase in cathode bias. Estimation of Hurst exponent using rescaled range analysis technique with values of H between 0.5 and 1 and algebraic decay of autocorrelation function provide signatures of long-range temporal correlations in the chaotic fluctuations and underlines the coexistence of complexity behavior.