All solid-state nanosecond pulsed generators based on Marx and magnetic switches

Abstract

An all solid-state Marx modulator utilizing Insulated Gate Bipolar Translators (IGBTs) is capable of outputting pulses with variable pulse width, repetitive pulse frequency and varying voltage amplitude. But the relatively slow turn-on speed of IGBT with high current loads result in slow rise time of output pulses. If a magnetic switch (MS) is combined with an all solid-state Marx, it will be quite simple to obtain nanosecond pulses with rise times under 100 ns. In this paper, several topologies for pulsed generators are proposed based on an all solidstate Marx and MS. When MS is connected in series with Marx, the rise time of the 200-Ampere load pulse is reduced from 560 ns to 85 ns. Besides, the switch-on loss of all IGBTs is considerably reduced. When a peaking capacitor is added, a 30 kV exponential decaying pulse with a rise time of 36 ns is obtained on a 100 ¿ resistor load. When the peaking capacitor is replaced by 20 m long pulse forming line (PFL), a 12.4 kV rectangular pulse with 223 ns pulse width (full width at half maximum), 44 ns rise time and 56 ns fall time is obtained on a 50 Ω resistor load. When the PFL is replaced by a Blumlein Transmission Line (BTL), the amplitude of the load voltage can be doubled on the price of a larger pre-pulse. Besides, generator with BTLs is quite proper for dielectric barrier discharge (DBD) loads. Experiments show that over 10 DBDs are excited in 4 μs under a single shot, which means extremely intense plasma is produced due to the accumulation effect. This phenomenon suggests great potential value for industrial applications.