Electromagnetic Characteristics Of Targets Coated With Plasmas And Its Applications In Stealth Technology

The plasma stealth is a novel stealth technology in theory. It is also a burgeoning interdisciplinary and vary complex a systems engineering. It includes plasma physics, theory of electromagnetic field, radar technology, mechanical and electrical engineering.The study of target plasma stealth has attracted much attention from the Russia, the United States and many other countrfes around the world because of its advantages, of revolutionary effect on intending stealth technology. Hence, the study of target plasma stealth technology is of a practical signiilcance.In this paper, the WKB method and the finite-difference time-domain (FDTD) method are applied to study the electromagnetic characteristics of target coated with different plasmas. Some plasma stealth theories are described. It includes inhomogeneous unmagnetized plasmas refraction and absorption the incident electromagnetic wave, magnetized plasmas and unmagnetized time-varying plasmas absorption the incident electromagnetic wave. Some novel finite-difference time-domain methods for dispersive media and anisotropic dispersive media are presents. The innovations of this paper include:Firstly, the refractive inhomogeneous plasma stealth is studied. The electromagnetic-wave paths in plamas are given by the principle of calculus of variation in this paper. The effect on refractive RCS reduction of the target coated with non-uniform plasmas is presented. The relationship between the density of electrons in plasma spheres and the reversal of electromagnetic wave or the reduction of the RCS of a target is investigated.Secondly, the collisional absorption stealth of inhomogeneous isotropic plasma is studied. The WKB method is used to calculate the amount of reflection coefficient of a plane wave normally (or obliquely) incident on a conductive plane covered with inhomogeneous plasmas. The plasma density profiles could be parabolic or linear. The relation between collisional absorption of the EM-wave and the plasma density, plasma collision frequency, and incident wave frequency is obtained. Meanwhile, the FDTD method for inhomogeneous, collision, isotropic plasma is presented. Then the method is used to calculate the amount of reflection and absorption of an EM-wave incident on a conductive plane covered with plasmas.Thirdly, the collisional absorption stealth of inhomogeneous magnetized plasmas is studied. The absorption of circularly polarized and the X-mode EM-wave by inhomogeneous magnetized plasmas that cover the conductive plane is discussed under different conditions. Besides, the current density (JE) convolution finite-difference time-domain (JEC-FDTD) methodology for dispersive media is extended to anisotropic magnetized plasmas. The highefficiency and accuracy of the method are confirmed by computing the reflection and transmission through a magnetized plasma layer, with the direction of propagation parallel to the direction of the biasing field. A comparison to frequency-domain analytic results is included.Fourthly, we present the target stealth by using time-varying switched plasmas. The frequency upshifting of incident electromagnetic wave by rapid creation plasma is examined. We also describe the collisional absorption of EM waves in time-varying switched plasmas. And the reflection coefficients of EM wave are counted. Besides, a finite-different time-domain (FDTD) algorithm is applied to study the bistatic EM scattering by a conductive cylinder covered with inhomogeneous, collision, warm, time-varying plasma. The bistatic RCS of conductive cylinder covered with inhomogeneous time-varying plasma are calculated under different conditions.Fifthly, some novel finite-difference time-domain methods for dispersive media and anisotropic dispersive media are presents. At first, a new FDTD method called piecewise linear JE recursive convolution (PLJERC) FDTD method is derived using the piecewise linear approximation and the recursive convolution relationship between the current density J and the electric field E. Then, we extend this approach to anisotropic magne...