The Study Of Lower Hybrid Drift Instability In Inhomogeneous Plasmas

A variety of micro-instability can be excited in the current sheet, these micro-instability may lead to anomalous resistivity which plays an important role in initial stages of magnetic reconnection in the collisionless plasma. In particular, the lower-hybrid drift instability (LHDI) has often been considered as a possible candidate for producing anomalous resistivity. In addition, the LHDI is measured in related experiment when the Magnetic reconnection occurs and it is found that the LHDI has an important effect on magnetic reconnection. However, there is not still a thorough understanding with regard to the fundamental physics of the contribution of the LHDI to magnetic reconnection.In this dissertation, we study the linear LHDI in current sheet including multi-species ions by using kinetic theory and the nonlinear lower hybrid wave in an inhomogeneous plasma by using two fluid theory. We discuss the effects of the steady state of the current sheet and multi-species on LHDI. There are mainly six aspects in our work as follows:In the first chapter of the dissertation, some basic concepts are introduced and some recent research developments for micro-instability in current sheet are reviewed. In particularly, the theoretical and experimental research development of the LHDI are shown.In the second chapter, the LHDI in the Harris current sheet with three species of particles is investigated using kinetic theory under the local approximation. Firstly, the Harris current sheet in a three-species plasma is obtained from zero order Vlasov Equation and Ampere equation; then the dispersion relation of linear LHDI in the Harris sheet in the presence of negative ions could be obtained, and the numerical results show that the negative ion enhances the growth rate and reduces the real frequency of the LHDI. In addition, such LHD wave is unstable in a finite kz value range and propagates almost perpendicularly to the magnetic field.In the third chapter, for space observations that O+ions are often present and even dominate the plasma sheet, we consider the effect of O+ions on the LHDI using the nonlocal kinetic theory. It is found that the fastest growing mode is not monotonic with O+content and temperature, and there exists a minimum in the growth rate with the increase in O+contend and temperature.We study the LHDI in a current sheet consisting of particles with theκvelocity distribution in the intermediate wavelength regime ky(?)～1 using kinetic theory. From the linearized Vlasov-Maxwell system, we obtain the corresponding eigenvalue equation, which is solved using a finite-element representation of the eigenfunction, the numerical results show that this unstable mode has even-and odd-parities and an important electromagnetic component, the addition of hot particles (decreasingκ) can decrease the growth rate and modify the mode structure of the most unstable LHD waves.Using the kinetic theory, the linear LHDI in the plasmas with a weak guide field By is investigated, the results shows that the symmetry property of the mode structure and of the perturbed field is destroyed. The presence of Bv increases the growth rate, the amplitude, especially in the component Az and the electromagnetic component of the eigenmode.We study the nonlinear lower hybrid drift wave in the inhomogeneity plasma using two fluid theory, electron velocity can be obtained by drift approximation and the nonlinear lower hybrid drift wave can be described by the Kdv equation using the charge quasi-neutral condition, the results show both amplitude and width of the corresponding soliton solution decrease as the inhomogeneity of the electron temperature and density increases, and the amplitude approaches an asymptotic value.