The Research On Electromagnetic Pulse Attenuation Technology

Electromagnetic pulse (EMP) is a transient electromagnetic phenomena. With the development of physics, the research of nanosecond pulse became an important problem to resolve. Seen from time domain, the rising edge of nanosecond pulse is very steep. Meanwhile the band-width of nanosecond pulse is very wide in frequency domain. This is the focus and also difficulty of electric signal measurement techniques. Electromagnetic pulse can influence or destroy electronic parts, circuits and equipments through various coupling ways. With the development of nuclear technology and electromagnetic weapons, the theories and techniques of EMP and its engineering protection have been attracting more and more attentions in the world since the 20th century 70's.Due to the feature of EMP, it has stringent requirements on the bandwidth of the test system, the maximum test range, and the dynamic range, etc. Testing methods have been the focused content on the study of pulsed electromagnetic field for a long time. The common methods about measurement of high-voltage pulse have the measurement system composed mainly by divider and the digital storage oscilloscope, the measurement system composed mainly by calculus links and the digital storage oscilloscope, and optical measurement system, etc. In the measurement system composed by divider and the storage oscilloscope, as the converter, the impedance mismatch between divider and components of the system (high-voltage wire, output cables, and oscilloscope, etc.) may cause reflection, oscillation, and the differences of the initial divider ratio and the steady-state divider ratio. It also seriously affects the accuracy of measurement results. So the research of attenuation technology has important practical significance in the measurement.In this paper, it mainly makes a study on the electromagnetic pulse attenuation technology based on existing theories and techniques. Describe the composition of pulse measurement system and the requirements of impulse response. On this basis, analyze the performance of resistive divider. Also I introduce the factors of the measurement system, such as impedance matching, measuring cables, oscilloscope and so on. And recount the principle and method of impedance matching. It makes a targeted assay of the factors about affecting the corresponding performance. Research the choices of divider parameter and probe the design and performance improvement of high-voltage pulse attenuator. Choose the finite element method based on differential equations, and use HFSS which is the special software for the high-frequency electromagnetic field to be calculated and simulated. Then I obtained in the simulation waveform and field distribution. The prototypes about the resistor divider and attenuator is produced according to the simulation results, using good properties and applicable to high power circuit of metal oxide film resistors. While I design and make the insulating sleeve and wick for the connector in the electromagnetic pulse simulator testing. In the experiment, I actually measured the features of the divider ratio, time-domain impedance, and Frequency domain standing wave ratio.Through the experimental results, it shows that the divider ratio is lower inaccuracy, and both the divider and attenuator are good at transmission performance. It can well meet the actual needs of the measurement of high-voltage nanosecond pulse.