Plasma parameter diagnosis method based on broadband reflection coefficient curve curvature analysis

Abstract

The invention discloses a plasma parameter diagnosis method based on broadband reflection coefficient curve curvature analysis, which comprises the steps of sending multi-frequency-point electromagnetic waves within a certain frequency band width through a swept-frequency signal source; emitting the multi-frequency-point electromagnetic waves into plasmas to generate reflection, measuring returnloss of the reflected signals, obtaining a complex reflection coefficient of each frequency signal caused by the plasmas after a calibration algorithm and de-noising smoothing treatment, and obtainingplasma parameter electron density and collision frequency corresponding to each frequency point through back-stepping calculation; projecting the complex reflection coefficient to a complex plane toobtain a multi-frequency-point data fitting curve, and determining a confidence coefficient weight of each frequency point back-stepping calculation result; and multiplying the plasma parameter electron density and the collision frequency corresponding to each frequency point subjected to back-stepping calculation by respective confidence weights, and summing to obtain the result. According to theinvention, the electron density and the collision frequency of the plasmas can be obtained at the same time, time delay of the reflected signals does not need to be measured, and the accuracy is high.

Description

Technical field [0001] The invention belongs to the technical field of plasma diagnosis and relates to a plasma parameter diagnosis method based on curvature analysis of a broadband reflection coefficient curve. Background technique [0002] When the high-speed aircraft re-enters the atmosphere, the surface of the aircraft generates high temperature ionization of the surrounding air due to air friction, and a large number of positive ions, neutral particles and electrons appear around the aircraft, thus forming a plasma that wraps the aircraft, called a plasma sheath , The plasma sheath will have a serious impact on the electromagnetic wave signals sent and received by the aircraft, and the spacecraft will lose ground communication, which is called the reentry communication interruption. Plasma is the fourth form of matter. In order to characterize the microscopic properties of plasma, plasma diagnostic techniques need to be used to determine plasma parameters. At present, the m...

AI Technical Summary

Problems solved by technology

The more commonly used diagnostic methods at present have Langmuir probe method, microwave method and spectroscopic method; The needle goes deep into the plasma, so the material of the probe will affect the diagnostic results, and when the temperature is too high, the probe will deform and cause a large error in the measurement of the volt-ampere characteristic curve

The existing microwave diagnostic technology mainly uses the method of frequency sweep to measure the reflected signals of multiple frequ

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