A thesis entitled electrostatic microinstabilities in plasma

Investigation is made for the linear excitation of kinetic buneman (electron-ion two-stream) instability in : (i) Unmagnetized, homogeneous isothermal Ti=Te Plasma and (i i) Magnetized, inhomogeneous isothermal Ti=Te plasma. A dispersion equations describing the system for both cases are obtained and solved for the threshold values. In addition, expressions for the frequencies and growth rates of oscillations when the current velocity slightly exceeds the instability threshold velocity have been derived in the linear approximation. It is found that on considering the effect of the thermal motion of electrons and ions, this will lead to the decrease of the growth rate of instability in comparison with that of hydrodynamic one. Besides, it is found that the effects of inhomogeneity and external static magnetic field may lead to some plasma stability. Also, we have studied-based on the frame work of the weak turbulence theory- the nonlinear dispersion equation for electron-sound instability in hot ion plasma (Ti > T ) due to current propagating in the Z-direction parallel to external magnetic field Ho . The matrix elements describe the nonlinear interactions and scattering of the waves in the plasma are calculated to obtain the conditions and the growth rate of such instability