Research On Test System Of The Double-Exponential Nanosecond Pulsed E-Field

EMP has become the focus of national research because of its great harm. In order to simulate EMP environment, refer to the requirement of relevant standards for transient electromagnetic radiation sensitivity measurement, a small double-exponential nanosecond pulsed E-field testing system has been built in this paper. The system mainly consists of high-voltage pulse source, GTEM cell, resistance divider, field probe and oscilloscope. Pulse source feeds voltage to the GTEM cell then a transient EM field forms inside, resistance divider and field probe are used to monitor the change of pulse voltage and electric field. The main work is as follows:1) Optimization design has been taken to improve the withstand voltage of GTEM cell's connector, and optimized GTEM cell's connector can withstand 20kV pulse voltage. The VSWR of GTEM cell is around at 1.6 from low frequency to 2GHz except for 605MHz of 1.73. After debugging resistance divider, the performance has been improved with its 3dB bandwidth up to 400MHz. The rise time stables at Ins of square wave pulse response, it can be used to measure the high voltage pulse.2) In the design of high voltage pulse source, a design scheme has been proposed of the source. The influence of the load resistance and capacitor to ripple voltage and voltage drop of cascade generator has been analyzed. The structure design of the cascade generator, gas spark switch and its trigger circuit has been completed. The static puncture test and triggered puncture test has been taken to the pulse source, and the influence of the gas pressure, electrode distance, electrode shape to the pulse waveform has been analyzed based on the test result. When the pulse source is working at self-puncture condition, the peak output voltage can reach 20kV, the average rise time is about 2.46ns, the average half peak pulse width is about 30ns, the output waveform can fit with standard waveform properly.3) Based on the original field probe, by adjusting the value of dividing capacitor and the length of monopole antenna to reduce the circuit input signal, removing the optical transmission module to take full advantage of the scope of the operational amplifier, thereby the maximum field measured by probe can be improved. The influence of the dividing capacitor to the probe's bandwidth has been analyzed, the structure design and simulation of the probe has been completed. The probe's antenna factor in the time domain and frequency domain has been calibrated. Based on the antenna factor, the 3dB bandwidth, linearity and E-field range measured by probe has been determined in the condition of different dividing capacitor value and antenna rod length.The basic function of the test system can meet the standard requirements, but there are still some deficiencies need to be improved.