2018 Volume 13 Pages 3401073
Dynamic behaviors of ionization waves influenced by feedback are experimentally studied. Delayed feedback is useful for stabilization of chaotic system; it has applicability in controlling chaos. However, delayed feedback can also result in a stable system becoming unstable, or even chaotic. The ionization wave system in our experiment has one spatial degree of freedom. Neon gas is introduced into a glass tube that has been evacuated to high vacuum, and a glow discharge Ne plasma is produced by an electric current between two electrodes. Fluctuations in the light intensity are sampled using two photodiodes placed a certain distance apart; the intensity sampled from one photodiode is fed back to the system through an external circuit. The largest Lyapunov exponents are calculated from the time series sampled from the photodiodes. The value of the largest Lyapunov exponent is positive for chaotic oscillations, with higher values for more chaotic systems. The value becomes close to zero for a system with periodic oscillations. In our studies, we found that a chaotic system can be made periodic by applying feedback while the distance between two photodiodes is a multiple of a particular value.
