中国空间科学技术

中国空间科学技术 ›› 2024, Vol. 44 ›› Issue (5): 155-165.doi: 10.16708/j.cnki.1000-758X.2024.0083

• 论文 • 上一篇    下一篇

返回式航天器动态等离子体低频电磁波信道特性研究

孙斌，黄才，龙吟，丁凯，刁伟鹤，张慧雯   

  1. 1 北京空间飞行器总体设计部，北京100094
    2 北京理工大学 集成电路与电子学院，北京100081
  • 出版日期:2024-10-25 发布日期:2024-10-21

Channel characteristics of dynamic plasma sheath around re-entry vehicles on low-frequency electromagnetic wave propagation

SUN Bin， HUANG Cai， LONG Yin， DING Kai，DIAO Weihe，ZHANG Huiwen   

  1. 1 Beijing Institute of Spacecraft System Engineering， Beijing 100094， China
    2 School of Integrated Circuits and Electronics， Beijing Institute of Technology， Beijing 100081， China
  • Published:2024-10-25 Online:2024-10-21

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摘要： 考虑低频电磁波在等离子体鞘套下强穿透能力，低频法被认为是一种缓解黑障影响的可行方法。现有研究建立了低频电磁波在稳态等离子体鞘套下衰减模型，但是忽略了动态等离子体信道对信号的影响，缺乏对该信道特性的深入认识。因此，对动态等离子体低频电磁波信道特性开展研究，以动态等离子体信道响应为基础，结合有色高斯分布时变电子密度模型，建立了动态等离子体信道统计模型，获得了该信道一阶统计特性，幅度概率密度函数Pr（r）为幂函数-高斯函数结合分布，相移概率密度函数Pφ（φ）为正切函数-高斯函数结合分布，功率谱密度函数SHi（ω）为有色噪声分布。为验证该信道统计模型有效性， 开展多种状态的数值仿真（电子密度1018~1019/m3，碰撞频率1 ~ 5GHz，低频电磁波频率1~30MHz），仿真结果与理论结果高度吻合。随着电子密度从1018/m3增大至1019/m3，幅度、相移随机波动程度增强，Pr（r）均值μr从1.33增大至34.04，标准差σr从0.13增大至14.34；Pφ（φ）均值μφ从0.58增大至5.81，标准差σφ从0.11增大至1.19，功率谱发生衰减和展宽现象。刻画的动态等离子体低频电磁波信道，对低频通信调制算法设计和性能评估具有重要意义。

关键词: 返回式航天器, 等离子体鞘套, 黑障, 动态等离子体信道, 低频电磁波

Abstract: Low-frequency （LF） electromagnetic （EM） waves exhibit stronger transmission behavior under a plasma sheath， which has a positive impact on mitigating radio blackout. Previous work has established attenuation models for LF EM waves under the steady-state plasma sheath，but neglected the time-varying properties of the plasma， lacking an in-depth understanding of the channel characteristics. Therefore， this study focuses on the channel characteristics of dynamic plasma sheath on LF EM waves. The channel stochastic model of the dynamic plasma is established at LF EM wave bands， where the channel response of the dynamic plasma is merged with the colored-Gaussian time-varying electron density model. The first-order statistical properties of the dynamic plasma channel are obtained. The probability density function （PDF） of envelope Pr（r） is a power-Gaussian function， the PDF of the phase shift Pφ（φ） is a tangent-Gaussian function， and the power spectral density （PSD） function SHi（ω） is a colored noise function. To validate the effectiveness of the proposed channel statistical model， the muti-state numerical simulations are conducted， and the simulation results are in good agreement with the theoretical results. The electron density is 1018-1019/m3， the collision frequency is 1.5 GHz， and the frequency of LF EM waves is 1.30 MHz. When the electron density increases from 1018/m3 to 1019/m3， the degrees of random fluctuation on envelope and phase shift increase. The mean of Pr（r） increases from 1.33 to 34.04， and the standard deviation of Pr（r） increases from 0.13 to 14.34； the mean  of Pφ（φ） increases from 0.58 to 5.81， and the standard deviation of Pφ（φ） increases from 0.11 to 1.19； the PSDs are attenuated and broadened. The results reveal the channel characteristics of dynamic plasma at LF EM wave bands， which is significant for designing LF communication modulation algorithms and evaluating the performance of LF communication systems.

Key words:  , re-entry vehicles； plasma sheath； radio blackout； dynamic plasma channel； low-frequency electromagnetic waves