||Study on Dynamic Behaviors of Ionization Waves Influenced by Feedback in a Glow Discharge Plasma
Fukuyama, Takao ,
Plasma and Fusion Research
13p.3401073 , 2018-06-12 , プラズマ・核融合学会
Dynamic behaviors of ionization waves influenced by feedback are experimentally studied. Delayed feedbackis useful for stabilization of chaotic system; it has applicability in controlling chaos. However, delayedfeedback can also result in a stable system becoming unstable, or even chaotic. The ionization wave system inour experiment has one spatial degree of freedom. Neon gas is introduced into a glass tube that has been evacuatedto 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 intensitysampled from one photodiode is fed back to the system through an external circuit. The largest Lyapunovexponents are calculated from the time series sampled from the photodiodes. The value of the largest Lyapunovexponent is positive for chaotic oscillations, with higher values for more chaotic systems. The value becomesclose to zero for a system with periodic oscillations. In our studies, we found that a chaotic system can be madeperiodic by applying feedback while the distance between two photodiodes is a multiple of a particular value.