Influence analysis of uncertainty of chemical reaction rate under different reentry heights on the plasma sheath and terahertz transmission characteristics

Plasma sheath prediction of hypersonic vehicle is critical to radio frequency (RF) blackout solutions as well as vehicle design and development. In this paper, an optimized chemical reaction (OCR) model by considering the difference in reaction rate coefficient under different re-entry heights is proposed to obtain more accurate plasma sheath distribution. In the OCR model, the correction coefficient of chemical reaction rate at different heights is obtained by deriving the relationship between vehicle surface temperature and reaction rate. Further, through the coupling with hypersonic plasma flow model and co-simulation with terahertz transmission model, the in-fluence of reaction rate uncertainty on the plasma sheath and terahertz transmission characteristics under different heights is studied. The reaction rate uncertainty has little effect on the collision frequency and sheath thickness, but has a significant effect on the electron density. Numerical simulations and comparisons with flight data validate the electron density prediction accuracy of OCR model was improved by more than 13.1% compared with the traditional chemical reaction (TCR) model, which causes prediction accuracy of signal attenuation at 0.05 THz improves about 25%, and it gradually decreases with the increasing terahertz frequency. The above conclusions are of great significance for the communication attenuation prediction and RF blackout schemes.