When a vehicle reenters the earth’s atmosphere at a hypersonic speed, the surrounding air molecules are dissociated and ionized by the tremendous heat due to atmospheric friction, and a plasma sheath surrounding the hypersonic vehicle’s surface will be formed. The plasma sheath greatly attenuates the electromagnetic (EM) waves radiated from an onboard antenna through reflection and absorption effects, and intermittent communication outage and blackout are frequently caused by the plasma sheath. Therefore, research on the interaction mechanism between EM waves and plasma sheath is of great significance.
Many studies have been conducted on the propagation characteristics of EM waves at the plasma sheath. However, the propagations of obliquely incident EM waves in the reentry plasma sheath have not been actively studied, and only a few studies dealt with it.
Han Yong Su, a researcher at the Faculty of Physics, has investigated the propagation properties of obliquely incident S-polarization electromagnetic waves into reentry plasma with bi-Gaussian electron density profile.
Based on the continuous boundary condition of electromagnetic (EM) waves in multilayer plasma, he deduced a scattering matrix equation of the obliquely incident S-polarization EM wave, and investigated the properties of reflection, transmission and absorption in terms of incident angle, plasma electron density distribution, and collision frequency, respectively.
The numerical results show that when the incident EM wave obliquely passes through the plasma sheath, the amplitudes of reflectance, transmittance and absorptivity are obviously modulated by the incident angle, electron density profile, and collision frequency. In addition, he confirmed that the transmittance peak and absorptivity peak are shifted from a lower frequency to a higher frequency with the increase in the incident angle, electron density profile and collision frequency.
You can find more information in his paper “Numerical Investigation for Propagation Characteristics of Obliquely Incident EM Waves in Plasma Sheath” in “Proceedings of KUTIC-2025”.