The Research And Design Of Microwave Measurement System In A Ballistic Range Of The Closed Cavity

A very long high-temperature non-equilibrium plasma wake dragged behind of theflying body atmospheric reentry, result in the strong scatter and absorption of themicrowave signal, the different trails make different radar cross section and cause theaircraft can not be invisible or communication interruption. Ballistic range experimentsimulate the reentry phenomenon was first carried out by NASA for Flight Simulatorbody, the domestic for ballistic range wake electron density measurement experimentcarried out late, the ballistic range wake diagnostic techniques far behind the UnitedStates and other developed countries. In this paper, theoretical analysis on the low endof the ballistic range wake electron density measurements, microwave closed cavitydiagnostic system for ballistic range wake plasma diagnostic measurements, the maincontent of this paper is as follows:First, we make a introduction of the application background of the topic and theend of the ballistic range at home and abroad trace diagnostic technology developmentstatus, makes the introduction of the plasma dielectric effect in the electromagnetic field,the electromagnetic field propagation conditions in the non-magnetized plasma in theplasma body diagnostic techniques is discussed, microwave techniques can achieve thenon-contact measurement without contaminating the measured plasma and can tracemeasurement the ballistic target plasma tail in a very short time the measured change ofthe plasma parameters by using microwave techniques.Second, the characteristics and laws of growth the ballistic range wake areanalyzed, microwave resonator measurement system have high sensitivity feature, goodspatial resolution and transient response diagnostic techniques, we analysis the plasmasmeasurement theory of resonant cavity based on the perturbation theory, and design theclosed cavity resonator to meet the target of parameters measurement.Finally, the approximate range of plasma density perturbation and measurementsensitivity is analyzed, according to measurement theory, demonstrated the dynamicrange of measurement indicators plasma. Compared to the closed cavity and the ideal closed cavity electric field distribution, the cutoff waveguide in depth part of the closedcavity make ameliorate compare with the closed cavity and the ideal closed cavity, thedepth part of the cutoff waveguide makes the center of the cavity radial electric fielddistribution more flat. The errors in plasma measurement by the microwave cavitytechnique is analyzed, the error correction formula is given by combined with closedcavity medium perturbation theory.This paper completes the microwave cavity diagnosis system applied in theballistic target of the closed cavity design, analysis and measurement theory,demonstration and error correction, prove plasma measurement by the microwavecavity technique correct.