  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 the application of
negative voltage on the cathode with respect to the grounded chamber using one
of the power supplies. On the application of positive voltage to the anode
using second power supply results in formation of a 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.
