Influence of peaking capacitors in reducing rise times of high-voltage nanosecond pulses

High-voltage (a few hundred kilovolt), short pulses (microseconds to to nanoseconds) have been found to be effective for various biological decontamination applications, such as cleaning of water with bacteria/algae. Marx generators are most commonly used for this purpose. A serious disadvantage of Marx generators is the increase in rise times due to series inductance. To alleviate this effect, peaking capacitors have been used to produce early time, fast-rising pulses that the Marx generators otherwise cannot supply due to their relatively high series inductance. This paper presents the results of the design and development of a 600-kV, 50-ns-rise-time, and ∼250-ns-duration pulse generator using a peaking capacitor. A 132-kV condenser-type bushing of 650-kV BIL and 230-pF capacitance was used as a peaking capacitor to reduce rise time. The effect of the peaking capacitor was also studied employing circuit modeling of the generator and the influence of various parameters was investigated. There is a good correlation between the experimental and the numerical results.