The Development Of High Voltage Nanosecond Electromagnetic Pulse Attenuator

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.Attenuator allows the high voltage pulse source a wide range of output is adjustable; it can protect the circuit; it can be used to match the load; adjust the fast pulse waveform; ultra-broadband source or EMP analog source and even sometimes have permanent access to an impedance matching of the attenuator;it can also be used for the rapid burst generator waveform calibration.EMP simulation techniques, which is often have a peak of tens of kV, a few hundred kV high-voltage pulse,when researching of the high voltage nanosecond pulse, high responsiveness, high attenuation, reliable performance of the attenuator is essential. Therefore, the development of the attenuator is of great significance.In this paper, it mainly makes a study on the electromagnetic pulse attenuation technology based on existing theories and techniques. Introduced the related theory of transmission line and the standing wave ratio, concept of the impedance matching, and the basic cause of attenuation in transmission of the process.Describe the composition of pulse measurement system and the requirements of impulse response. On this basis, analyze the performance of attenuator. 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 performance of the attenuator. Research the selection of attenuator parameter,exploration the methods of high voltage pulse attenuator design and performance improvement. 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. After calculating the attenuation trend in transition section by simulation, and the conical transition is determined at both ends, as well as the structure design of the main linear transition way, and shunt resistance grounding method. Then the model is set up. Using ANSYS calculation section impedance. According to the simulation calculation and the results of structure optimization, using good properties and applicable to high power circuit of metal oxide film resistors,making the prototype of attenuator. Experiment measure the attenuation characteristics of attenuator,it shows that, high voltage pulse by the attenuator transmission waveform before and after good consistencya, it achieves30%and40%of the pulse attenuation, it can meet the practical needs of measurement system. High voltage pulse in rising edge is steep by the attenuator, falling along of the waveform is quite smooth, no obvious reflection below25kV, illustrate the attenuator impedance matching; and the falling along of more than25kV pulse apears reflection, showing under the high voltage system,the distributed capacitance and inductance have impact on the measurement system. Overall, prototype test qualified,the system can meet the experiment requirements, the attenuator is applicable to the high voltage nanosecond electromagnetic pulse attenuation.