Haijun Ren

Dispersion of linear waves in quantum plasmas

The dispersion of linear waves in a uniform cold quantum plasma is derived using the quantum hydrodynamic equations with the magnetic field of the Wigner-Poisson system. The dispersion of the Langmuir wave becomes whistler-like due to quantum effects and, therefore, the Langmuir wave can propagate in a cold plasma. It is also found that quantum effects do not affect the dispersion of the left-handed, right-handed, and ordinary waves.

Quantum effects on Rayleigh–Taylor instability in magnetized plasma

The effects of the quantum mechanism and magnetic field on Rayleigh–Taylor (RT) instability in an ideal incompressible plasma are investigated. The explicit expression of the linear growth rate is obtained in the presence of fixed boundary conditions. It is shown that the magnetic field has a stabilizing effect on RT instability similar to the behavior in classical plasmas and RT instability is affected significantly by quantum effects. Quantum effects are also shown to suppress RT instability with the appropriate physical quantities. Some astrophysical parameters are discussed as an example to investigate the new effects.

Jeans instability in quantum magnetoplasma with resistive effects

The Jeans instability in dense quantum plasmas is investigated in the presence of two dimensional magnetic fields and resistive effects. The resistive effects are shown to introduce instability whether the perturbation is stable or not in the ideal magnetohydrodynamic model. The analytical expressions of the growth rate of Jeans instability are obtained for both the finite and remarkable resistive effects cases. The results are relevant to dense astrophysical objects, e.g., neutron stars and the interior of white dwarfs, as well as low-temperature laboratory plasmas.

Electrostatic drift modes in quantum dusty plasmas with Jeans terms

Electrostatic drift waves (EDWs) are investigated in nonuniform quantum magnetized dusty plasmas by taking into account dust gravitational effects with the help of the quantum hydrodynamic model. Ions and electrons are viewed as low-temperature Fermi gases, whereas quantum effects are neglected for the dust grains. The analytical dispersion relationship of the quantum EDWs is derived. Quantum effects are shown to affect the dispersion of EDW significantly. The Jeans terms induce a driftlike instability, which does not exist with the absence of gravitational effects. The criteria and growth rate of the kind of instability are presented. Our results are relevant to dense astrophysical objects such as the interiors of astrophysical compact objects (e.g., white dwarfs and neutron stars).

The effect of the Hall term on Jeans instability in quantum magnetoplasma with resistive effects

The Jeans instability in dense quantum plasmas is investigated by taking into account the Hall term and resistivity in the presence of two-dimensional magnetic fields. The general dispersion relation is presented. The presence of the Hall term introduces a new wave mode which does not exist in the ideal magnetohydrodynamic framework. Two limiting cases with respect to the Hall effect are discussed. The Hall effect is shown to induce a frequency shift but does not change the instability criterion. The resistivity exhibits damping or destabilizing effects on the plasma system under different circumstances. The analytical expressions of the growth/damping rate of Jeans instability are obtained for both the finite and remarkable resistivity cases in the absence of the Hall term.

Effects of shear flow and transverse magnetic field on Richtmyer–Meshkov instability

The effects of shear flow and transverse magnetic field on Richtmyer–Meshkov instability are examined and the expression of the interface perturbation is obtained by analytically solving the linear ideal magnetohydrodynamics equations. It shows that the perturbation evolves exponentially rather than linearly in the presence of shear flow and magnetic field when va<1−AT2δu∕2, where va is the modified Alfven velocity, AT is the Atwood number, and δu is the relative shear velocity, respectively. The shear flow acts as a destabilizing source, while the magnetic field is a stabilizing mechanism of the shocked corrugated interface problem. The whole analysis is based on the assumption that the fluid is incompressible.

Electrostatic drift waves in nonuniform quantum magnetized plasmas

Electrostatic drift waves (EDWs) in nonuniform quantum magnetized plasmas are described by the quantum hydrodynamic model. Electrons are viewed as a low-temperature Fermi gas. Analytical expression of the dispersion relationship of the quantum EDW is presented. Quantum effects are shown to affect the dispersion of the EDW significantly. The effects on the dispersion relation due to the magnetic field and spatial inhomogeneity give rise to results similar to the classical case. Our results should be relevant to dense astrophysical objects, e.g., neutron stars, magnet-stars, and white dwarfs.

Group velocity of extraordinary waves in superdense magnetized quantum plasma with spin-1/2 effects

Based on the one component plasma model, a new dispersion relation and group velocity of elliptically polarized extraordinary electromagnetic waves in a superdense quantum magnetoplasma are derived. The group velocity of the extraordinary wave is modified due to the quantum forces and magnetization effects within a certain range of wave numbers. It means that the quantum spin-1/2 effects can reduce the transport of energy in such quantum plasma systems. Our work should be of relevance for the dense astrophysical environments and the condensed matter physics.

Effect of toroidal rotation on the geodesic acoustic mode in magnetohydrodynamics

Theoretical research on the geodesic acoustic mode (GAM) induced by equilibrium toroidal rotation flow in the tokamak plasmas is approached by using ideal magnetohydrodynamic model. The dispersion relation of the GAM is presented by taking into account magnetic field perturbations. It is shown that β can decrease the frequency of the GAM.

Electrostatic drift modes in quantum pair plasmas

Electrostatic drift waves in a nonuniform quantum magnetized electron-positron (pair) plasma are investigated. An explicit and straightforward analytical expression of the fluctuation frequency is presented. The effects induced by quantum fluctuations, density gradients, and magnetic field inhomogeneity on the wave frequencies are discussed and a purely quantum drift mode appears. The present analytical investigations are relevant to dense astrophysical objects as well as laboratory ultracold plasmas.