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The Optical Sensor Technology For Measuring The High Pulse Current

Posted on:2006-02-20Degree:MasterType:Thesis
Country:ChinaCandidate:X Y DengFull Text:PDF
GTID:2168360155968177Subject:Optics
Abstract/Summary:PDF Full Text Request
In this thesis, the background and the significance of optical current sensor for measuring high pulse current were stated. The theory and the experiments were extensively and deeply studied to improve the technique.The magneto-optical effect, Verdet constant and Jones matrix were deduced and expounded by using the classic theory of interaction between light and media. With electromagnetic theory of light, We found that the polarization of the light kept the same when the reflection of incident light satisfied critical reflection or dual-quadrature reflection. Based on these, the influences on measuring accuracy were analyzed, which were introduced by the defects of the magneto-optical probe , the drawbacks of the polarization devices and the linear birefringence. Also the relationship between four output signals and the pulse current was numerically stimulated with two typical currents.Based on the traditional optical current sensor with two optical paths, a new optical current sensor with four optical paths was designed and set up. In new system the azimuth of polarization can be determined uniquely by sine signals and cosine signals adopted simultaneously. While in traditional system the azimuth of polarization cannot be determined uniquely when it was beyond the monotonous zone of sine function. And the range of measurement can be largely expanded. According to measuring requirement, the main parts were analyzed and the system was established.The data process in the new systemwas accomplished by two methods according to the amplitude of pulse current. Arcsine. function was used to process low pulse current signals. arctangent function was used to process high pulse current signals. The method for processing high pulse current signals was based on following mechanism. Firstly, Four output signals with drawback were converted into two signals by calculation. Secondly, Lissajous figure was drawn by two forementioned signals. Then the amplitude difference and the phase difference between two curves, the orthogonal coordinate of the ellipse center were attained from Lissajous figure. Finally, the pulse current was obtained through inputting the foregoing parameters into current formulation. The advantages of this method are that there is no insensitive zone and the quality of original signals can be deduced from Lissajous figure.At four different charging voltage, the short pulse current of electrical gun was measured. It agreed well with the measured result of Rogowski coils. Three different pulse currents with maximum value 60kA, 73kA and 90kA were measured. The results also accorded well with the theoretical value of current. This proved feasible and effective to measure high pulse current with optical current sensor with four optical paths.
Keywords/Search Tags:magneto-optical effect, critical reflection, dual-quadrature reflection, optical current sensor, pulse current
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