Study On The Electromagnetic Scattering Of Targets Coated With Plasma Sheath

The electromagnetic scattering of targets coated with plasma sheath is investigatedwith finite difference time domain (FDTD) and physical optics (PO), respectively.Firstly, the model of the hypersonic vehicle is created, and then vehicle peripheral flowfield is simulated with simulation software such as Fluent. Secondly, the iterativedifferential formulation of FDTD for Maxwell’s curl equations in plasma sheath isderived; Finally, FDTD and PO are employed to analyze the electromagnetic scatteringof targets coated with plasma sheath. The main contributions of this dissertation are asfollows:1. According to the basic principle of fluid mechanics, the high temperature airflowgoverning equations of the plasma sheath are constructed. Non-equilibrium flow of5constituent elements of double temperature air chemical model, which is provided inFluent software, is applied to solve the Navier-Stokes equations of the aircraftperipheral plasma flow field. And then the electronic density distribution of the plasmasheath is calculated.2. Based on the basic properties and the formulation mechanism of the flow fieldcoated with plasma for the hypersonic vehicle, the iterative differential formulation forMaxwell’s curl equations in the plasma sheath are derived with FDTD, and theimplementations of FDTD for electromagnetic scattering problems are discussed.3. The geometrical model of a cone-shaped hypersonic vehicle is built, andelectromagnetic scattering properties of target coated with (non-magnetized, magnetized)plasma are investigated by JEC-FDTD method. The influences of the electron density,the plasma layer thickness, the plasma frequency, the plasma collision frequency, theplasma cyclotron frequency, the incident wave frequency, as well as the incident angleon electromagnetic scattering are analyzed.4. The aircraft surface is discredited with triangular patches. Based on physicaloptics (PO) method, basic formula of reflectance is derived from flow field simulationparameters of vehicle. Electromagnetic scattering of the cone-shaped vehicle coatedwith plasma sheath is investigated with the improved PO method, and the dependenceof electromagnetic scattering characteristics on flight speed, incident frequency andincident angle are analyzed.