Studies on the Effect of Angle of Attack on the Transmission of Terahertz Waves in Reentry Plasma Sheaths

Abstract

Abstract-The communication 'blackout' in the reentry stage of a space mission is a serious threat to the reentry vehicle. The terahertz (THz) technology is supposed to be a potential solution to the 'blackout' problem in the recent decade. In the present paper, the relation between the THz waves' transmission in the reentry plasma sheath and the angle of attack (AOA) of the vehicle is investigated. A three-dimensional numerical model is introduced in order to obtain the plasma parameters in the reentry plasma sheaths. The computation results show that both the electron density and the electron collision frequency vary with the AOA. As results, the transmission rates for the THz waves vary with the AOA as well. According to the analysis, microwave communication system is very likely to suffer from the 'blackout' in the reentry stage. The THz scheme is an effective solution. The fluctuation of AOA may weaken the signal strength received by the onboard antenna. On the other hand, keeping the AOA in an appropriate range is helpful for strengthening the received THz signals. Also, the AOA for the best THz communication quality is obtained according to the analysis.

Effect of Terahertz Antenna Radiation in Hypersonic Plasma Sheaths with Different Vehicle Shapes

“…Moreover, the model is reliable since the simulation results agree well with the RAM experiments results. This study uses the plasma sheath model to explore the antenna performance with different vehicle shapes, which is original and different from our previous works [8,12,13,16].…”

“…Electron density and the electron collision frequency have been revealed as the two most important plasma parameters that significantly affect antenna performance [9][10][11]. On the other hand, some previous studies reveal that the parameters of the plasma sheaths depend on many factors, e.g., atmospheric conditions [12], flight speed [8], angle of attack [13], and the shape of the vehicle [14], in which case antenna performance is affected.…”

Sub-THz signals’ propagation model in hypersonic plasma sheath under different atmospheric conditions

“…Previous studies have revealed that the hypersonic plasma sheath is influenced by many factors including the aerodynamic shape [10], the angle of attack [11,12] and the flight trajectory [13]. Besides those parameters, the plasma sheath is obviously influenced by the atmospheric conditions around the hypersonic vehicle.…”