Kaifen He

Effect of adiabatic variation of dust charges on dust-acoustic solitary waves

Abstract The effect of dust charging and the influence of its adiabatic variation on dust-acoustic solitary waves is further studied. A more reasonable normalization for the dust velocity by the dust-acoustic speed is adopted, which varies self-consistently with the system parameters. By employing the reductive perturbation technique we derive small-amplitude dust-acoustic solitons with varying dust charges. The Sagdeev potential shows that only the rarefactive solitary waves exist when the Mach number lies within an appropriate regime depending on the system parameters. An approximate similarity law is obtained and discussed in this dust-charge-fluctuation system.

Dust-acoustic solitary waves and double layers in dusty plasma with variable dust charge and two-temperature ions

With two-temperature ions in dusty plasma, the effects of variable dust charge on small-amplitude dust-acoustic solitons and large-amplitude dust-acoustic solitary waves are investigated. It is found that both compressive and rarefactive solitons (and solitary waves), as well as double layers, exist. The introduced small, but finite, number density of the lower temperature ions provides the possibility of the coexistence of large-amplitude rarefactive with compressive dust-density solitary waves. The amplitudes of those dust-density solitary waves become smaller and the regime of Mach number is extended wider for the variable dust charge situation compared to the constant dust charge situation.

Burst and coherence resonance in Rose–Hindmarsh model induced by additive noise

Abstract With the aid of Rose–Hindmarsh (RH) model, the effects of additive Gaussian white noise (GWN), Ornstein–Uhlenbeck noise (OUN) and quasi-monochromatic noise (QMN) on neurons have been numerically studied and compared. According to the dynamic behavior of RH model near the critical Hopf bifurcation points, the mechanism of additive noise induced burst and coherence resonance are analyzed. By computing and comparing the mean interspike intervals, power spectral densities, signal-to-noise ratios, degree of coherences, and probability density of interspike intervals, we have found that, with a proper choice of noise intensities, the coherence resonance or autonomous stochastic resonance can be exhibited in RH model. The results also indicate that the QMN induced firings are easier to be phase locked than that by GWN or OUN induced firings.

Attractive potential in weak ion flow coupling with dust-acoustic waves

Abstract For a weak ion flow coupling with collective dusty-acoustic waves, it is demonstrated that there exists an attractive potential necessary for the formation of dusty plasma crystals with the characteristic spacing of potential minima less than plasma Debye length, which agrees with the experimental results in some conditions.

Dust shielding and correlation function for dusty plasmas

Dust shielding and correlation function are investigated using a viscoelastic fluid theory, which allows for internal energy relaxation. The corresponding dispersion relation for dust-acoustic waves is derived. The dust static structure factor is calculated using the fluctuation-dissipation theorem. It is found that when the shear viscosity and relaxation time satisfy a certain condition the static structure factor of the strongly coupled system retains the Debye–Huckel form. In general, the characteristic shielding of the dust is found to be determined by a combination of the dust and plasma Debye lengths.

CONTROLLING SPATIO-TEMPORAL CHAOS VIA SMALL EXTERNAL FORCES

Abstract The spatio-temporal chaos in the system described by a one-dimensional nonlinear-drift wave equation is controlled by directly adding a periodic force with appropriately chosen frequencies. By dividing the solution of the system into a carrier steady wave and its perturbation, we find that the controlling mechanism can be explained by a slaving principle. The critical controlling time for a perturbation mode increases exponentially with its wave number.

Reversal of phase velocity of a negative-energy mode and bistability in a driven-damped drift wave system

Abstract The eigenvalues of the steady states in a nonlinear drift wave system driven by a sinusoidal wave are investigated. A relevance is found between the appearance of bistability and the fact that the negative linear phase velocity of one resonance mode reverses nonlinearity in the frame following the driving wave. The system energy can be enhanced when this negative-energy mode is changed into a positive one. The wavenumber for the occurrence of the resonance varies with the driving frequency of the external wave. This fact leads to the repeated appearances of groups of bistable states in the parameter space.

Multistable structure in a Korteweg-de Vries system driven by a solitary wave

Abstract The dynamical behavior of a Korteweg-de Vries (KdV) system driven by a solitary wave is studied. A hierarchy of hystereses, i.e. multistability, for the steady wave momenta is found in the system. Winding number bifurcation occurs for the steady wave solution on every hysteresis.

MODIFIED DUST-ACOUSTIC SOLITONS BY ADIABATIC VARIATION OF DUST CHARGES

By the multi-scale expansion method an effect of adiabatic variation of dust charges on dust-acoustic soliton is investigated. It is found that the amplitude of the soliton decreases while its width narrows in comparison with the case of constant dust charges.

GAP SOLITARY WAVE COEXISTING WITH BISTABLE STEADY WAVES

Abstract A new kind of solitary waves is found coexisting with bistable steady waves in driven drift-wave system. The energies of these steady waves distribute in the gap between that of the bistable steady waves. The gap state is a combined result of the carrier steady wave and the soliton-like structure of perturbation wave trapped by the carrier. The effect of trapped structure is to reduce the ‘potential well’ of carrier wave.