The Electrostatic Instabilities In A Plasma Shock Front

In a plasma shock front, there are extremely high density and temperature gradients. So, the particle and heat diffusive fluxes caused by the density and temperature gradients are very large and the corresponding difference between the electron and ion diffusive fluxes will produce large charge separation (strong electrostatic field) in front. The one of the effects of this electrostatic field on the non-neutral shock is that it-self or it together with the parameter gradients can drive several instabilities on the equilibrium (steady state) shock front. These instabilities are a kind of new electrostatic modes, which are qualitatively different from those well known neutral modes (e.g. Rayliegh-Taylor or Richtmyer-Meshkov instability) driven only by the parameters gradient in the neutral shock front or discontinuity.These new mentioned instabilities are investigated in this text with high frequency (ω≥ω_pe) and low frequency (ω≤ω_pi) respectively in a plane (one dimensional) plasma shock front by double fluid equations and Poisson equation. It can be concluded that: 1) In the case of high frequency, the instabilities are driven by the electrostatic field or /and parameter gradients, and the real parts of instabilities are similar to the one of electron electrostatic (plasma) wave, the growth rate in paralleling direction is about two magnitudes larger than in the perpendicular direction. 2) In the case of low frequency, the instabilities are also driven by the electrostatic field or/and parameter gradients, and the real parts of instabilities are similar to the one of ion electrostatic (plasma) wave, the growth rate in paralleling direction is in the same magnitude as the growth rate in the perpendicular direction. But more we find that there exit an absolute unstable mode—zero-frequency instability mode. This text we also give the dependencies of real frequencies and growth rates on the steady profiles of n_e0(x),u_e0(x),T_e0(x) and E₀(x) in both cases.