Low-stray inductance structure to improve the rise-time of a Marx generator

Abstract

Recent works have extended the feasibility of a broadband device for electromagnetic radiations. This device consists of a high-gain antenna driven by a compact, self-contained and voltage-adjustable generator (Mayes et al., 2001). With this and other applications in mind, the authors have pursued a program to develop and characterise a repetitive, high voltage, nanosecond rise-time Marx generator. It was designed, built and successfully tested. Experiments were planned to reach a nanosecond rise-time, a voltage level around 200 kV and a few tens Hertz repetition rate. A new low inductance structure is used in order to improve the switching performances of the whole generator. The Marx generator allows the authors to obtain energy per pulse closed to 30 J and rise-times down to 2.15 ns. In an attempt to reduce once again the rise-time of the pulse, a modification was realised on the last stage of the Marx assembly. Improvements of this system are discussed. A measurement device, based on the principle of a capacitive divider, was also made to measure both the amplitude and the rise-time of the pulse delivered by the generator. Calibration tests, in frequency and transient domain, were performed and the results are detailed.