The Regulation Of Electron Density Distribution Of High-speed Target Plasma By Magnetic Field

The phenomenon of free electrons in the plasma sheath absorbing,reflecting and scattering electromagnetic waves can cause a series of electromagnetic effects,resulting in communication black barrier which will restrict the development of adjacent space highspeed aircraft.To solve the electromagnetic science problem caused by plasma sheath,it is necessary to produce a similar spatial distribution inhomogeneous plasma to simulate.This paper proposes to solve the problem of non-uniform distribution regulation by means of electromagnetic regulation to meet the requirements that Non-uniform distribution of plasma density space under simulated flight conditions and the experiment requirement of the density change can reach 2~3 magnitudes within 10 cm,It is of great significance to change the spatial distribution non-uniformity of plasma and the effect of magnetic field on plasma.The electron density distribution in the specific region of plasma jet will be changed when the motion direction of charged particles in plasma and the diffusion of plasma are affected by applying a magnetic field in this paper.Through building the model of the flow of the plasma,the coupled magnetic field,laminar flow,temperature field and concentration field,and considering the impact compound effect of charged particles,the movement rule of the charged particles in a magnetic field is obtained and the influence of different magnetic field configuration on the electron density distribution of high-speed target plasma is get based on the magnetic fluid theory of plasma.The research work and contribution of this paper are as follows:1.A theoretical model for the interaction between constant magnetic field and plasma is established.Combined with the theory of magnetic fluids,the plasma equations and diffusion coefficients are modified,a complete set of MHD is obtained.The coupling of multiple physical fields is realized with the equation,and the simplified plasma mathematical model is get by reasonable assumption,the applied magnetic field controls the distribution of plasma by changing the direction and diffusion of charged particles,all of these provide a theoretical basis for the subsequent solution.2.A multi-physical field coupled plasma flow simulation model is established.According to the calculating equations,a two-dimensional axisymmetric geometric model of plasma flow is established,the method of function definition of plasma parameters,the definition of the physical field that satisfies the flow of the plasma,the setting method of boundary conditions,the equation coupling method of each physical field,as well as grid division algorithm and solution setting method are given,the fluid simulation model is optimized according to the solution problem and the optimal mesh division method and the solution sequence are determined in the end.3.The regulation effect of static magnetic field on electron density distribution is studied.Firstly,the effects of different coil currents,number of turns,positions and number on the distribution of magnetic field strength and magnetic force lines are simulated and analyzed.The magnetic field of different configuration is set up,combined with the analysis of the mechanism of the magnetic field acting on the plasma,the study shows that magnetic field has a constraint on the electron density of plasma and the electron density distribution will converge to the axis.4.The distribution of the fluid temperature and the fluid velocity are studied by simulation,the influence of changes about temperature,velocity and initial electron density on electron density distribution of plasma is obtained.According to the distribution of plasma velocity and temperature at different moment in the cavity field,the correctness of simulation setting is verified.Researches show the temperature,velocity and initial electron density have positive effects on the radial gaussian distribution of the plasma,and the larger the parameter value is,the greater the radial gradient value of electron density.The theoretical model and simulation model of plasma flow under the constant magnetic field are established in this paper,and the effect of different parameters on the electron density of plasma is analyzed,all of those provide theoretical basis for the parameter setting and the coil distribution in the control of non-uniform plasma.