Doubly forced anharmonic oscillator model for floating potential fluctuations in DC glow discharge plasma

Highlights: • Evolution of a multiple anodic double layer controlled using two power supplies. • Order-chaos transitions observed with the evolution of double layer. • A doubly forced anharmonic oscillator model used to describe the experiment. • The model realized the experimentally observed dynamical features. • The model can be extended to complex system with large number of forces. The Floating Potential Fluctuations (FPF) observed in a dc glow discharge plasma powered with two sources is modeled using an anharmonic oscillator with two forcing terms. In the discharge system, one of the electrode is biased to a negative voltage source (i.e. cathode), and the second electrode is biased to a positive voltage source (i.e. anode), while the stainless-steel vacuum chamber is grounded. The dc glow discharge plasma is generated by application of negative voltage on the cathode with respect to the grounded chamber using one of the power supplies. On application of positive voltage to the anode using second power supply results in formation of potential structure on achieving the triggering criteria. This potential structure is referred as anodic double layer (ADL). The evolution of ADL is associated with FPF. Therefore, FPF is analyzed to characterize the ADL's dynamical features. In this work, the experimentally observed FPF compared with numerically obtained oscillations using an anharmonic oscillator model with two forcing terms. Each of these forcing terms are associated with the two power supplies used in the experiment. The experimentally and numerically obtained oscillations from the model are studied using phase-space plot, FFT, Largest Lyapunov exponent (LLE). The dynamical features of oscillations obtained by the model show strong agreement with the experiment and can be extended for a description of complex systems driven by multiple forces.