Nonlinear time-series analysis of current signal in cathodic contact glow discharge electrolysis

Abstract

In the standard two-electrode configuration employed in electrolytic process, when the control dc voltage is brought to a critical value, the system undergoes a transition from conventional electrolysis to contact glow discharge electrolysis (CGDE), which has also been referred to as liquid-submerged micro-plasma, glow discharge plasma electrolysis, electrode effect, electrolytic plasma, etc. The light-emitting process is associated with the development of an irregular and erratic current time-series which has been arbitrarily labelled as “random,” and thus dissuaded further research in this direction. Here, we examine the current time-series signals measured in cathodic CGDE configuration in a concentrated KOH solution at different dc bias voltages greater than the critical voltage. We show that the signals are, in fact, not random according to the NIST SP. 800-22 test suite definition. We also demonstrate that post-processing low-pass filtered sequences requires less time than the native as-measured sequences, suggesting a superposition of low frequency chaotic fluctuations and high frequency behaviors (which may be produced by more than one possible source of entropy). Using an array of nonlinear time-series analyses for dynamical systems, i.e., the computation of largest Lyapunov exponents and correlation dimensions, and re-construction of phase portraits, we found that low-pass filtered datasets undergo a transition from quasi-periodic to chaotic to quasi-hyper-chaotic behavior, and back again to chaos when the voltage controlling-parameter is increased. The high frequency part of the signals is discussed in terms of highly nonlinear turbulent motion developed around the working electrode.

Band‐Pass Filter and Relaxation Oscillator using Electric Double‐Layer Capacitor

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Parallel random bitstreams from a single source of entropy based on nonthermal electrochemical microplasma

“…Submerged nonthermal microplasmas can be realized by biasing a small electrode, slightly in contact with an electrolyte, with a high enough positive or negative DC voltage, relative to a much larger counter electrode. [1][2][3][4][5][6][7][8] The optical emissions can be visually localized within a thin gaseous sheath of a few tens of micrometers that forms around the smaller electrode, thus insulating it from the surrounding solution. [1,3,4,7] If, for whatever reason, the gas film is breached by the moving liquid boundary, there will be a very fast surge in power to reform it again and re-establish the plasma regime, which makes the process somehow self-sustaining.…”

“…The microplasma system consisted of a small Pt electrode of 0.5-mm diameter, barely in contact with an anolyte solution of 1-mol/L H 2 SO 4 , and a large surface area Pt foil serving as the counter electrode. [3][4][5] The spacing between the two electrodes was about 3 cm. The Pt needle was negatively polarized in all experiments, using a programmable Sorensen (Ametek) XG 300-5 DC power supply.…”

Autonomous Navigation of Unmanned Aerial Vehicles based on Android Smartphone

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