Periodic nonlinear wave–wave interaction in a plasma discharge with no external oscillatory driving force

Abstract

Experimental measurements of time series and frequency spectra characterize a periodic nonlinear interaction between pairs of self-excited, propagating, ionization waves simultaneously present in the positive column of a neon glow discharge. No periodically varying external driving force is applied. The interaction is the spatio-temporal extension of the previously established temporal periodic pulling process, the incomplete entrainment of a driven nonlinear oscillator. The particular mode playing the role of the driving perturbation in the interaction can be selected and is identified by inspection of the asymmetric, multisideband spectrum of light fluctuations, which reflect the system’s dynamics. A comparison between the spatio-temporal and temporal periodic pulling shows that the former is associated with a relatively strong driving force.

Spatiotemporal signatures of periodic pulling during ionization-wave-mode transitions

“…9 Hysteresis results in a difference of approximately 10% in the values of I D associated with the upward and downward transitions between pairs of modes. 4,10,11 The dominant mode coexists with low-amplitude secondary modes that are apparent in both the frequency and wavenumber spectra along the entire plasma column. As the current is incremented toward a transition value, the prospective a͒ Electronic mail: mkoepke@wvu.edu b͒ Present address: Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstrasse 1, 17 491 Greifswald, Germany.…”

“…In previous studies of the wave-wave interaction being investigated here, only the temporal modulation of the frequency was demonstrated. 10,11 II. EXPERIMENTAL RESULTS Figure 1 shows the space-time evolutions of the transition from a higher-frequency mode to the next-lowerfrequency mode ͓Fig.…”

“…Periodic pulling, a general driven-oscillator phenomenon in nonlinear systems, has been described theoretically 13 and demonstrated experimentally in a variety of systems, 14-18 but its spatiotemporal manifestation has been recognized only recently. 10,11 Periodic pulling is the result of incomplete entrainment, in which one mode's frequency is repeatedly pulled toward that of the other mode but never locks, and consequently, the modes are frequency modulated. As reported here, in the case of spatiotemporal periodic pulling, the frequency and wave number are modulated in space and time.…”

Electron drift caused by rf field gradient creates many plasma phenomena: An attempt to distinguish the cause and the effect

“…All the theoretical elaborations on the measurements of the plasma steady state have been studied. But, as the plasma quantities are numerous and bound together, we are not able to know what is the cause and what is the result, and the state becomes chaotic (Koepke et al 1996;Klinger 1998;Block et al 2001). In the present paper, it is proved that the rf-electric potential gradient gives an azimuthal drift velocity especially to electrons (ions are far away from resonance).…”

The big contradiction between the perturbation theory and the chaotic state. A detailed mathematical analysis indicates when the plasma is stable or unstable

“…[5][6][7] In such cases, the plasma may change to a chaotic state. 8 These two different plasma configurations have been studied extensively by the research team of the Plasma Laboratory of 'Demokritos'.…”