Research On The Simulation & Modeling Of Reentry Spacecraft Plasma Sheath To Communication Attenuation

When space vehicles (such as satellite, missile, space shuttle and the reentry module of the spacecraft. etc) reentry atmosphere at hypersonic speed, a plasma sheath enveloping the spacecraft begins to come into being. The sheath is composed of plasma, and the plasma is a medium which will exert influence on communication of the vehicles, such as absorption, reflection, refraction, dispersion etc, even can full cutoff communication which is called as communication blackout.In order to study this special reentry communication environment problem, in early 1960s American invested hugely to conduct radio attenuation measuring experiment, such as RAM plan, and through the RAM - C1, RAM - C2 and RAM - C3 test, they got a great deal of technical data and experience; from 1980s China began a large number of ground tests, such as feasible ways ground test of reentry communications. These studies mainly focused on the research of plasma sheath shape, structure and characteristics, computation and modeling of plasma sheath electronic density distribution, calculation of plasma reflection coefficient and transmission coefficient, and the physics, chemistry means to eliminate plasma etc. The scholars have made outstanding contributions in their fields in the research of reentry communication attenuation.This article is based on the whole ship plasma sheath in reentry process, on the basis of previous studies a new research scheme is proposed: by modeling the spacecraft in 3D contour, reentry process, spacecraft surrounding flow field temperatures, pressures and electron density distribution, combining with integrated computation, a 3D real-time reentry spacecraft communication attenuation model can be gained. According to this model, we can find out the attenuation value of every point of the spacecraft at different altitudes. This model well be the fundamental of further research on blackout countermeasure technologies, and has important significance to investigate the problem of reentry communication between the spacecraft and ground.