空间飞行器远尾区诱发场的调制不稳定性

Modulational instability for an induced field in the far-wake region of a space vehicle

空间飞行器穿过电离层时,其远尾区与等离子体发生的非稳态相互作用可以通过一组高频场和密度扰动的非线性耦合方程来描述.从该组方程出发,通过线性分析得到扰动的色散方程.理论分析和数值计算表明,飞行器远尾区诱发场是调制不稳定的,它将会坍塌成小尺度的局域结构,并形成密度空穴,这为隐形飞行器的探测提供理论依据;诱发场的特征尺度与最大增长率不仅依赖于泵波振幅与扰动波矢量之间的夹角,同时也受到泵波能量密度的影响.

Non-steady interaction between spacecraft with antenna and plasma can be described by a set of nonlinear coupling equations of high-frequency field and density disturbance in the far wake region of space vehicles. On the basis of the nonlinear coupling equations, the dispersion equation of perturbation is obtained through linear analysis. Theoretical analysis and numerical calculation indicate the induced field is modulational unstable and will collapse into spatial localized structures, meanwhile, density cavitons will be generated. The characteristic scale and maximum growth rate of the induced field depend not only on the angle between the amplitude of pump waves and perturbation wave vector, but also on the energy density of pump waves.