Numerical Simulation Of Non-Steady Interaction Between Moving Bodies And Plasma In Compression Region

When the bodies move in the upper ionosphere,there exist series of complex non-steady interactions. The interactions concentrate on two regions:the compressed region in the front and the rarefied region in the wake. Through the interactions the moving bodies make the density of plasma around them disturb. This disturbance of density excites different kinds of plasma waves. So it is important for exploring the stealth vehicle to investigate the interactions and all kinds of plasma waves.The interaction between a body in space and its plasma environment is one of the basic problems in space plasma physics. This paper is devoted to a detailed investigation of non-steady interaction between the moving body and plasma in compression region,whose dominating equations are obtained and whose phenomena are simulated. Through two-fluid and two-time-scale approximation,the dominating equations,which show the non-linear coupling between high frequency modulational field and the density disturbance of electrons and ions,are obtained. That is to say,high frequency modulational field radiated from the antenna system of moving bodies influents the charge distribution in plasma,while the disturbance of the charge distribution influents the field conversely. In general,there is no way to get the equations' analytical solution because of the characteristic of non-linear coupling. In this paper,based on the amplitude transport equation of fast varying field and the low frequency disturbance equation of electron density,the evolutions of the density distribution of charged particles and the collapse of electric field have been calculated numerically in two dimensions with three field components under the condition of transverse wave. The numerical results of non-steady interaction between moving bodies and plasma in compression region are presented. In numerical simulation,the FTCS method,i. e. time forward difference and space central difference method,has been used. The results show that the density cavitons and potential solitons are formed due to the modulational instability if the radiation of the antenna as a pump wave source is sufficiently intense. From the distribution of density caviton,we can trace out the moving bodies by means of observing the structure and intensity of the density caviton although the bodies may be stealth vehicles.