Study Of Microwave Attenuation In The Rocket Exhaust

Experiments show that the primary components of rocket exhausts plume are solid and liquid dusty particles, which will be charged negatively by interaction with the charged particles in plume. To the great extent, affect the electromagnetic characteristic of microwaves propagating through it and detectability and control of aerocraft. However, the dusty particles were not considered in previous investigation on the electromagnetic characteristic of plume. Based on kinetics, this paper presents the modification of the electromagnetic characteristic of plume plasma by considering the dusty particles.Firstly, the paper introduces the interior structures and physical and chemical processes of rocket exhaust plume. Then we investigate the density distribution of electron and dusty particles and their size distribution in exhaust plume. The study shows the electron density is in the order of 101 7 m^-3 ---- 101 9 m^-3 , the dusty particles density 101 0 m?3 ---- 101 5 m?3 and the dusty particles size 1μm---- 10μm. Also, we derive the formulation of electric conductivity, dielectric coefficient and modulus decay of dusty plasma by considering the collision process between charged particles and charge process of dusty particles. Due to the charge process of dusty particles, the electric conductivity, dielectric coefficient and modulus decay of dusty plasma are larger than that of plasma.The rocket exhaust plume was taken as an example to prove the above conclusion. The relation of electric conductivity, dielectric coefficient with temperature, frequency and altitude is obtained. The results show that the above parameters augment with an raise in temperature, and decrease with an enhancement in frequency of microwave. Due to pressure, the decay of microwave through plume is different with increasing altitude.