电磁波在非均匀磁化的等离子体鞘套中传输特性研究∗

摘要

We use simulation software to simulate the plasma sheath flow field of RAM-II at four different altitudes, and get the distribution information of electron density, temperature, and Mach number of plasma sheath at four typical flight altitudes. On this basis, the paper analyzes the cause of the distribution at each altitude. Secondly, Z transform FDTD formula is used to solve the electromagnetic problem in the dispersed medium. According to RAM-II aircraft plasma sheath data, we calculate the power transmission coefficient and power reflectance coefficient of L, S-band electromagnetic waves by Z transform FDTD method at each altitude. Because of the strength of magnetic field used in actual aircraft cannot be uniform, in this calculation the plasma sheath and the magnetic induction are both non-uniform. The transmission characteristics are also different between left-hand circularly polarized waves and right-hand circularly polarized wave in the magnetized plasma. Finally, the paper gives some theoretical design advise about communication antenna for supersonic speed aircraft.%采用流场模拟软件模拟了十一组分RAM-II飞行器表面等离子体鞘套的分布，提取了四个典型飞行高度、飞行状态下的等离子体鞘套的分布信息。然后根据RAM-II飞行器等离子体鞘套数据，利用计算色散介质的Z变换FDTD方法主要计算了电磁波在四个不同高度处等离子体鞘套中的功率反射系数和功率透射系数。此外，根据目前可以做出的磁场强度的大小，对四个不同高度下的非均匀等离子体鞘套层按距飞行器表面的距离进行相应的非均匀磁化。由于左旋极化波和右旋极化波在磁化等离子体中的传输特性不同，最后对比了左旋极化波、右旋极化波在非磁化和磁化情况下的传输特性，对飞行器导航通信磁窗天线的设计给出建议。