Inlet Plasma Stealth Aircraft Design Parameters

Plasma stealth technology is a new way to achieve the stealth of plane. This paper focuses on the electromagnetic attenuation of aircraft inlet using high-frequency discharged plasma. We have done some exploratory studies by numerical calculations and experimental supports.Based on the stealth of inlet in the wave band of1GHz-2GHz, the desired plasma parameters were calculated by Finite Element Method (FEM) method. Two sorts of shape inlet was under investigation:cylinder-shaped and wedge-shaped. The simulation results show that there is a peek electromagnetic attenuation associate with the frequency of incident wave, electron number density and collisional frequency of plasma. The electromagnetic attenuation was influenced significantly by electron number density, the thickness of plasma, the shape of inlet cavity, and the polarized direction of incident wave, and so on.A cylindrical cavity with the material of glass fibre reinforced plastic was fabricated. Using the annular electrode to couple high-power radioheating source, the plasma was generated by ionizing Ar and He in cavity with a low air pressure. Its stealth characteristic was also verified. From the results obtained, there is a close agreement between simulation and measurement. The pre-calculated results are appropriate to foresee the absorbed wave band by plasma. It was proved that the plasma can be used in inlet stealth under some condition. The absorption of EM wave with covered plasma was proved to be significant. The single way attenuation is15dB.Electromagnetic scattering of EM wave is studied experimentally and theoretically for metal cavity and plasma-covered metal cavity. It is verified the feasible of plasma in inlet stealth for L-band waves.