Research On Key Technology Of Transient High Power Electromagnetic Pulse Field Measurement

With the development of electronic technology and the ubiquity of electromagnetic environment,the study of transient high power electromagnetic pulse(EMP)has received more and more attention.The transient high power EMP has several features,such as high peak field strength,wide dynamic range,fast rise time,large pulse width in the time domain and ultra-broadband characteristics in the frequency domain.As a consequence,it has a significant effect of interference and destruction on electronic equipment,which differs from conventional EMC sources.In this thesis,three key technologies are investigated for the measurement of single-pulse transient high power EMP fields with peak field strengths of not less than 100 V/m and a frequency range of megahertz to 5 GHz.For the measurement of transient magnetic fields,two kinds of multi-gap B-Dot magnetic field sensors are developed in the article.The differential-mode multi-gap magnetic field sensor can effectively reduce the problem of different output signals caused by the incident field in different directions.In addition,the common-mode multi-gap magnetic field sensor can increase the upper frequency of the sensor to four times the upper frequency of the currently known B-Dot sensor,which can expand the upper frequency to 3 GHz and above.On the basis,the performance of the B-Dot sensors against ionizing radiation is analyzed to provide a basis for the accurate measurement of EMP fields in the ionizing radiation environment.For the calibration of transient high power EMP sensors,the article proposes a time-domain joint calibration method.Firstly,the equivalence of rising edge calibration and frequency band calibration as well as the equivalence of amplitude sensitivity calibration and frequency domain calibration are verified through theoretical analysis.The performance of the two aspects of the sensor is calibrated separately by means of a TEM cell and a monocone,which improves the engineering practicality and simplicity.In addition,by calibrating the primary standard sensor in the TEM cell,the influence of the relative size of the sensor and the standard field generation device on the calibration accuracy is demonstrated numerically and experimentally.It is proposed that the calibration error can be reduced to within 10%for the relative size of the sensor less than 1/5.For the signal processing of the output signal of the sensor,the article adopts a MAP-based signal processing algorithm.The algorithm can effectively recover the electromagnetic field waveform of the incident signal.And the problem of tail drift,which exists in the numerical integration method,is better solved due to the good processing capability of noise.In addition,for two kinds of noise,Gaussian white noise and quantization noise,the effect of noise on signal recovery is studied under different signal-to-noise ratio conditions.As a consequence,the relative error of the recovered signal can be reduced to within 10%when the signal-to-noise ratio is higher than 30dB.Based on the above three key techniques,the article also carried out the electric field measurement of the impulse radiation antenna(IRA)and the magnetic field measurement inside the laser inertial confinement fusion device.Through the measurements in the two typical environments,some important regularities of electromagnetic environment distribution are obtained,which provide a basis for electromagnetic environment effect studies and electromagnetic compatibility design.