Quasiperiodic transition to spatiotemporal chaos in weakly ionized magnetoplasmas

Origin of transient and intermittent dynamics in spatiotemporal chaotic systems

Nonattracting chaotic sets (chaotic saddles) are shown to be responsible for transient and intermittent dynamics in an extended system exemplified by a nonlinear regularized long-wave equation, relevant to plasma and fluid studies. As the driver amplitude is increased, the system undergoes a transition from quasiperiodicity to temporal chaos, then to spatiotemporal chaos. The resulting intermittent time series of spatiotemporal chaos displays random switching between laminar and bursty phases. We identify temporally and spatiotemporally chaotic saddles which are responsible for the laminar and bursty phases, respectively. Prior to the transition to spatiotemporal chaos, a spatiotemporally chaotic saddle is responsible for chaotic transients that mimic the dynamics of the post-transition attractor.

Self-organized waves in annular rf weakly magnetized dusty plasmas

Self-organized waves and the associated dust particle motion are studied experimentally in a low-pressure annular rf weakly magnetized dusty discharge system. Low-frequency drift waves with strong modulation on plasma density and dark space (sheath) width, traveling azimuthally with mode number m=1, are self-excited. Period-n and quasiperiodic states are also observed at higher rf power. Dust particles in the liquid state show collective elliptical cyclic motion in the low-frequency ionization-drift wave but respond only weakly to waves with frequencies above 50 Hz. When dust is added to a dust-free magnetized discharge in which there exists an ionization drift wave at 20 KHz, the wave amplitude is reduced and the frequency is down shifted.

Self-organized oscillations of strongly coupled dust coulomb clusters in plasma traps

The self-organized oscillation of a strongly coupled dust Coulomb cluster with an elongated cross section in a weakly ionized rectangular plasma trap is investigated. Through an inverse supercritical bifurcation at the low rf power end, a low-frequency (about 5 Hz) limit cycle oscillation of the whole cluster associated with the intracluster compressional lattice wave and phase-locked oscillation of the glow intensity distribution is observed. It is caused by the interplay of the dust motion and the shrinking and expanding of the confining dark space.

Microscopic Particle Motions in Strongly Coupled Dusty Plasmas

The microscopic particle motions from the crystal to the disordered state of a dusty plasma with micrometer-sized silicon dioxide particle suspensions in a radio-frequency glow discharge system were studied through an optical microimaging system. Small-amplitude random motion around the lattice sites of the crystal state, relative domain motion with varying boundaries, cooperative hopping in the liquid state, and highly disordered motion with increasing radio-frequency power were observed. Chaotic states with different spatial scales under the coherent and stochastic coupling between dust particles and self-organized background plasma fluctuations were also demonstrated.