Broadband microwave reflectometry plasma diagnostic based on invariant point of reflection data

Reentry plasma sheath diagnostic plays extremely important roles in the research of the blackout problem. In this paper, a broadband microwave reflectometer based on the invariant point of reflection data has been designed and developed for the reentry plasma sheath diagnostic. The invariant point Y(omega(p), 1) is derivable from the broadband reflection data. The electron density and collision frequency are measured simultaneously. The diagnostic algorithm was verified by the simulation analysis and diagnostic experiment. The algorithm has low computational complexity and relatively high precision. This algorithm offers a certain reference value for the plasma sheath diagnostic of reentry vehicles or hypersonic vehicles in the future. Especially, the design of broadband VVD antenna with heat-resistant wave-transparent composites has certain practical values.