Influence of avalanche transistor switching mode on waveform characteristics of solid-state pulse source.

The design of the Marx circuit based on avalanche transistors (ATs) is one of the effective techniques for developing solid-state pulse sources to generate nanosecond pulses. However, the influence of the avalanche transistor as a switching device on the output pulse characteristics is still unclear. In this study, investigating the switching mechanism of the AT with a mixed-mode simulation of the semiconductor device has been accomplished. An experiment has checked the simulation model's transient switching characteristics. The switching mechanisms of ATs in the Marx circuit were divided into base triggering mode (BTM) and voltage ramp mode (VRM). This paper proposes a modified circuit for adjusting the output pulse parameters of solid-state pulse sources. The results show that to satisfy the simulation accuracy, the width parameter of the AT model in the BTM must be 100 µm, much less than the actual physical size. Because of the higher electric field when the initial impact ionization occurs, the AT operates at a higher switching speed in the VRM than in the BTM. In addition, since the carriers of initial impact ionization locate at the p-n0 interface or the n0-n+ interface, the AT switching process will oscillate in the VRM. All ATs in the modified Marx circuit switch to operate in the BTM. The leading edge of the output pulse increases from 275 to 1125 ps, and the pulse trailing oscillation has disappeared. The research results provide an important technical means for optimizing the output waveform of solid-state pulse sources.

Study of the time-domain electromagnetic pulse standard field generation setup and its application.

In this paper, a time-domain electromagnetic pulse standard field generation setup was designed and manufactured for transient electromagnetic pulse sensor calibration. The calibration setup is based on the mono-cone structure. It can produce a calculated electromagnetic pulse field with the electric field intensity from 100 V/m to 600 V/m. The quantity of the electric field intensity is traced to the national primary standard of the pulse parameter, the S parameter, and the length quantity. The standard uncertainty of the produced electric field is 2.4%. The waveform and field distribution of the standard field were verified by experiment. Based on this facility, the calibration methods and uncertainty evaluation methods for two types of electromagnetic pulse sensors (TEM horn and D-dot sensor) were proposed. Finally, we obtained the calibration results of the sensors. The standard uncertainties of the calibration are 3.6% for the TEM horn and 3.0% for the D-dot sensor.