Abstract
The “magnetic window” is considered a promising means to eliminate reentry communication blackout. However, the turbulence of plasma sheath results in phase jitter and amplitude turbulence of electromagnetic (EM) wave and may influence the eliminating effect. Therefore, the effect of fluctuating property of reentry plasma sheath on EM wave propagation when a magnetic field is used for eliminating blackout is investigated. For this purpose, a time-varying electron density model, which includes both temporal variation and spatial turbulence, is proposed. Hybrid matrix method is also employed to investigate the interaction between time-varying magnetized plasma and EM wave. The EM wave transmission coefficients in time-varying magnetized and unmagnetized plasmas are likewise compared. Simulation results show that amplitude variation and phase jitter also exist on transmitted EM wave, and the turbulent deviation increases as the degree of plasma fluctuates. Meanwhile, the fluctuation of transmitted EM wave attenuates at low-frequency passband and increases at high-frequency passband with the increasing magnetic field. That is, comparing with unmagnetized time-varying plasma, the fluctuation effect can be mitigated by using a magnetic field when the EM wave frequency is at low-frequency passband. However, the mitigating effect can be influenced by the nonuniformity of magnetic field.
Highlights
When spacecrafts reenter the Earth’s atmosphere or fly at hypersonic velocity, the surrounding molecules are dissociated and ionized due to the shock heating of the air or ablation of the heat shield material
Magnetic window method is used to eliminate the communication blackout problem caused by reentry plasma sheath
linear eddy model (LEM) is used for simulation of plasma electron density spatial turbulence, and the time domain variation is generated as Gaussian random process
Summary
When spacecrafts reenter the Earth’s atmosphere or fly at hypersonic velocity, the surrounding molecules are dissociated and ionized due to the shock heating of the air or ablation of the heat shield material. Only the effect of “magnetic window” method on the improvement of electromagnetic (EM) wave propagation in a steady-state plasma has been considered The parameters, such as electron density, of plasma sheath vary with the angle-of-attack variations, flying attitude adjustment of hypersonic vehicle, turbulent boundary layer, and nonuniform ablation.[10,11] Thereby, these dynamic physical factors inevitably affect the EM waves.[12,13,14,15,16,17] Yao et al have established a model of time-varying reentry plasma sheath and discussed the effect of turbulence perturbation on wave-phase jitter and amplitude fluctuation.[12] In Ref. 17, the influences of reentry time-varying plasma on the EM wave propagation were analyzed.
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