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A physical model of electrostatic shocks observed in space plasma is established by deriving the “Sagdeev potential” from the magnetohydrodynamic equations in a cylindrical coordinate system. The results show that the electrostatic density shock and its corresponding solitary electric-field structure can develop from an ion acoustic wave or an ion cyclotron wave if the Mach number and the initial electric field satisfy some conditions. Some features of the shock wave are discussed. The result can be used to interpret the electrostatic shock observed in geospace plasma. [ABSTRACT FROM AUTHOR]

Determines the solitary kinetic Alfven wave with a finite ion gyroradius. Amplitude of the solitons; Enhancement of the parallel propagation velocity of the solitons; Propagation of kinetic Alfven waves in the magnetosphere.

In the presence of ionospheric O[sup +] ions, the velocity shear instability of ultralow frequency surface wave in the plasma sheet is investigated. By considering protons and O[sup +] ions flow in the same macrospeed and keeping the velocity curl term in the magnetohydrodynamic equations, the general dispersion relation of surface wave perturbation was obtained. It is found that the velocity shear instability tends to happen in a range of wavelengths around a certain point, which was called the resonant point. At the resonant point, even in absence of velocity shear, the damping eigen-oscillations, which are caused by the dissipation, as well as the inhomogeneities of magnetic field and plasma density, coupled with the disturbed Alfvén wave and fed the energy into the disturbed wave through Alfvén resonance. The velocity shear makes the range of unstable wavelengths enlarge around the resonant point and even enhanced the coupling at the short wavelength side of the resonant point. The presence of ionospheric O[sup +] ions could obviously enhance the coupling. These results may be helpful in understanding magnetic pulsation (Pc5) and vertical plasma cooling in the plasma sheet, as well as substorm processes. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow with both perpendicular and parallel components to magnetic field is investigated in magnetized three-component cold dust plasma. It is found that K-H instabilities are mainly driven by the parallel component of the sheared dust flow. The perpendicular component of the sheared dust flow influences the extent of the oblique propagation of the unstable perturbed wave with respect to the ambient magnetic field. For a dense dust plasma, as the perturbed frequency is much higher than the dust charging frequency, the maximum damping rate of the perturbed wave due to dust charge fluctuations will reach the order of the dust charging frequency. In this case, the critical shear for the parallel K-H instability increases rapidly because of the charging processes in the long-wavelength perturbation. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]