大气环境中喷流等离子体隐身试验研究与分析

Experimental investigation and analysis on jet-plasma stealth in air surroundings

介绍了喷流等离子体隐身技术的原理性试验及其数值计算。试验是在大气环境中利用微型固体火箭发动机作为等离子体发生器,选择不同的发动机参数和推进剂控制发动机产生不同的喷流等离子体。在小双站角方式下,使用X波段连续波雷达系统测量了不同的喷流等离子体覆盖金属目标表面时的微波散射功率。试验结果表明,等离子体层厚度为9cm、电子密度分布接近为高斯分布、电子与中性气体的碰撞频率为高斯分布、峰值电子密度为1012/cm3量级、峰值碰撞频率为2.2×1011Hz的喷流等离子体对X波段微波具有明显的吸收作用,平均吸收达到90%。数值计算采用时域有限差分(FDTD)方法中的直接积分方法,用试验获得的等离子体层厚度、电子密度分布、电子与中性气体碰撞频率的空间分布等参数计算了有等离子体覆盖时金属目标的雷达散射截面(RCS),选用的微波频率为X波段的典型频率10GHz。数值结果表明,试验产生的特定等离子体能够有效地吸收电磁波的能量,减少RCS。数值计算结果和试验结果较吻合。

The paper presents principle experiment and numerical simulation of plasma stealth technology. Minitype solid rocket engines were used as plasma generators under the tests. Variant plasmas was produced by varying engine parameters and components of propellant fuel. The scattering microwave power of the targets which are coated with plasmas was measured by the bistatic radar system. The results show non-uniform plasma with depth of 9cm, density distribution of Ne （Y） = Ne0exp（ - y^2/a^2）, collisional frequency distribution of Ve（y） = Vc0exp（ - y^2/ a^2） , peak electron density of 10^12/cm^3 and peak collisional frequency of 2.2 × 10^11Hz, can effectively absorb microwave energy at X waveband. The mean value of the absorbed power is 90 %. Direct integration methods of FDTD are used to study the scattering of three dimensional targets which are coated with the plasma under the tests. By simulating the interaction of the electromagnetic wave with the un-magnetized plasma, the effects of the plasma parameters on the radar scattering cross section（RCS） are analyzed, which are obtained under the tests, such as the depth, electron density distribution and collision frequency of electrons and neutral atoms in plasma, etc. The results show that the plasma produced under special test conditions can effectively absorb microwave energy and reduce back scattering of the targets. The test results rather consisted with the numerical simulation results.