Радиопрозрачность ионизованной оболочки, образующейся вокруг гиперзвукового объекта в мезосфере

Abstract

This article discusses the basic properties of ionized gas shell formed around objects moving in the mesosphere at hypersonic speeds to determine the frequency band for the radio communication. Ionization occurs due to the energy of the shock wave. The thickness of the transition layer is defined between molecular distances. Limiting compression due to the Hugonio adiabat and depends on the number of degrees of freedom – for diatomic gas is equal to 6. The energy which remained when braking goes for heating of gas in a shock wave and, agrees Sakha, to ionization. Temperature field of the shell taking into account the heat transfer coefficient is much higher surface temperature of the object. Near the bow, which overheating, for example, Buran reaches 1400 °C, the gas temperature exceeds 10 000 °С – this is at a height 63 km and at a speed of 17 Machs. The shell is three-component gas. There are atoms (molecules), ions and electrons with a low degree of ionization. The main features are the frequency of collisions of electrons with atoms and the plasma frequency. If the plasma frequency exceeds the frequency of collisions, the medium is a gas plasma. If the frequency of collisions exceeds value of plasma frequency, gas doesn't reach a plasma status. The plasma frequency is critical: above the critical frequency gas plasma is dominated by the dielectric properties, and to the critical frequency – dominated conductive properties. Plasma sheath radio transparency if the value of the skin layer to the body exceeds the normal thickness of the shell. Calculations and model tests show that the transparency of the radio channel is provided in the centimeter range, where f > 9 GHz.