Effect of plasma flow evolution and angle of attack on the terahertz wave transmission characteristics enveloping hypersonic vehicles

Abstract Terahertz communication is thought of as a viable solution to the blackout issue induced by the presence of a plasma sheath. Previous studies have mainly focused on the external conditions such as the aerodynamic configuration and vehicle velocity on the terahertz communication, while neglecting the influence of spatiotemporal variations during the plasma evolution process and the angle of attack (AOA). In this work, the effect of plasma flow evolution and AOA on the terahertz communication is studied. Electron density and collision frequency distributions exhibit significant spatiotemporal variations during the plasma evolution process, leading to time-varying characteristics in terahertz propagation. And the steady-state of plasma sheath has a lower attenuation compared to the early and mid-stages. Furthermore, the influence patterns and mechanisms of AOA on the terahertz transmission are further explored. On the windward side, an increase in the AOA leads to higher electron density and collision frequency, while the plasma sheath thickness decreases, and the opposite trends are observed on the leeward side. Additionally, the electron density and collision frequency on the leeward side are significantly lower than those on the windward side, leading to reduced terahertz attenuation, and the lowest terahertz attenuation is observed at a smaller AOA of 4°. For an antenna position of L = 0.8 m, the critical terahertz communication frequencies for the leeward and windward sides are determined to be 0.1 THz and 0.16 THz. Finally, a communication scheme is proposed, recommending the leeward side as the communication end, combined with a smaller AOA of 4° and a frequency of 0.1 THz.