Mai-mai Lin

Interaction of two solitary waves in quantum electron-positron-ion plasma

The collision between two ion-acoustic solitary waves with arbitrary colliding angle θ in an unmagnetized, ultracold quantum three-component e-p-i plasma has been investigated. By using the extended Poincare-Lighthill-Kuo (PLK) perturbation method, we obtain the KdV equations and the analytical phase shifts after the collision of two solitary waves in this three-component plasma. The effects of the quantum parameter H, the ratio of Fermi positron temperature to Fermi electron temperature σ, the ratio of Fermi positron number density to Fermi electron number density μ, and the ratio of Fermi ion temperature to Fermi electron temperature ρ on the phase shifts are studied. It is found that these parameters can significantly influence the phase shifts of the solitons.

Rectification and phase locking in overdamped two-dimensional Frenkel-Kontorova model

The rectification phenomena and the phase locking for an overdamped two-dimensional Frenkel-Kontorova model system with commensurate structure under ac- and dc-driven external forces are demonstrated. As a function of longitudinal dc amplitude, the longitudinal velocity increases in a series of steps of height jν0. In the steps, rectifications in the transverse direction occur though there are no net dc force in the transverse direction. Our results can be applied to vortices in superconductors, classical electron motion, biomolecules moving through 2D arrays of posts, and especially in tribology. In these active ratchets the rectified velocities can be controlled by jν0.

Landau damping in a multi-component dusty plasma

Effect of the dust size distribution on the landau damping and the wave frequency is studied in the present paper. It is found that wave frequency increases as either the difference between the largest and the smallest dust size increases or the wave number increases. It seems that wave frequency is smaller for dusty plasma whose density of the smaller grains is larger than that of the larger ones, while it is larger in the opposite case. The effect of the dust size distribution can increase the Landau damping in the cases where the temperature of the dust grains is small enough or high enough.

Effect of multicomponent dust grains in a cold quantum dusty plasma

By employing the quantum hydrodynamic model for electron—ion—dust plasma, we derive a dispersion relation of the quantum dusty plasma. The effects of the dust size distribution on the dispersion relation in a cold quantum dusty plasma are studied. Both analytical and numerical results are given to compare the differences between the dusty plasma by considering the dust size distribution and the mono-sized dusty plasma. It is shown that many system parameters can significantly influence the dispersion relation of the quantum dusty plasma.

Response to “Comment on ‘Interaction of two solitary waves in quantum electron-positron-ion plasma’” [Phys. Plasmas 18, 084701 (2011)]

According to the comments of Akbari-Moghanjoughi that the electron-positron-ion(e-p-i) plasmas parameters σ representing the ratio of the positron to electron Fermi-temperature and p standing for the positron to electron number-density ratio are related by the equation of p = σ 3/2. Based on this conclusion, we have replaced the Figs. 1–6 (Ref. 1) in the present paper.

Effects of the relative motion of different particles on the wave instability in dusty plasmas

Theoretical study is carried out for the dust acoustic waves in a dusty plasma. The dispersion relation is obtained from the fluid dynamical model. It is found that the wave frequency depends on the electron number density, wave number, and the speed of electrons or ions. The dependencies of the instability on the system parameters are also discussed. It is found that the long wavelength wave is usually unstable, which may be useful in the plasma physics, especially in the magnetic confined fusion system or the charged beam dynamics in the accelerated driven system.

THE ANISOTROPIC CHARACTERS IN TWO-DIMENSIONAL LATTICE

The anisotropic characters of simple cubic lattice are investigated in this paper. Both the linear and nonlinear wave propagating in this lattice have been studied. The dispersion relation has been studied numerically. It is shown that the dispersion relation strongly depends on the directions of wave propagation. Generally, the direction of waves has the inclination angle α with respect to particle displacement. There are compressional waves α = 0 or transverse waves α = π/2 only for some special cases. The nonlinear waves in this lattice have also been studied. The anisotropic characters of this lattice for the nonlinear waves have also been shown. The compressional and transverse nonlinear solitons have also been studied. The characters of both solitons, such as amplitude and width, have been investigated.