A three-dimensional model is proposed in this paper to study the effect of the pulsed magnetic field on the density distribution of high flow velocity plasma sheath. Taking the typical parameters of plasma sheath at the height of 71 km as an example, the distribution characteristics and time evolution characteristics of plasma density in the flow field under the action of pulsed magnetic field, as well as the effect of self-electric field on the distribution of plasma density, are studied. The simulation results show that pulsed magnetic field can effectively reduce the density of plasma sheath. Meanwhile, the simulation results of three-dimensional plasma density distribution show that the size of the density reduction area is large enough to meet the communication requirements of the Global Position System (GPS) signal. Besides, the location of density reduction area provides a reference for the appropriate location of antenna. The time evolution of plasma density shows that the effective density reduction time can reach 62% of the pulse duration, and the maximum reduction of plasma density can reach 55%. Based on the simulation results, the mechanism of the interaction between pulsed magnetic field and plasma flow field is physically analyzed. Furthermore, the simulation results indicate that the density distributions of electrons and ions are consistent under the action of plasma self-electric field. However, the quasi neutral assumption of plasma in the flow field is not appropriate, because the self-electric field of plasma will weaken the effect of the pulsed magnetic field on the reduction of electron density, which cannot be ignored. The calculation results could provide useful information for the mitigation of communication blackout in hypersonic vehicles.

本文提出了一个三维模型来研究脉冲磁场对高流速等离子体鞘层密度分布的影响。以71 km高度等离子体鞘层的典型参数为例，研究了脉冲磁场作用下流场中等离子体密度的分布特征和时间演化特征，以及自电场对流场的影响。研究了等离子体密度的分布。仿真结果表明，脉冲磁场能有效降低等离子体鞘层密度。同时，三维等离子体密度分布仿真结果表明，密度降低区域的大小足以满足全球定位系统（GPS）信号的通信需求。除了，密度降低区的位置为天线的适当位置提供了参考。等离子体密度的时间演化表明，有效密度降低时间可达脉冲持续时间的62%，等离子体密度最大降低可达55%。基于仿真结果，对脉冲磁场与等离子体流场相互作用的机理进行了物理分析。此外，模拟结果表明，在等离子体自电场作用下，电子和离子的密度分布是一致的。然而，等离子体在流场中的准中性假设是不恰当的，因为等离子体的自电场会削弱脉冲磁场对电子密度降低的影响，这是不可忽视的。