Design, simulation, and development of bipolar pulse forming network based Marx generator for S band backward wave oscillator

Abstract

Pulse power systems have a wide range of applications, one of which is microwave generation. Microwave emission is associated with a certain time delay between the application of a high voltage pulse and the generation of the microwave signal. This time delay is known as microwave delay time, and it depends on the time period of the microwave signal being generated. As the time period of the microwave signal increases, the required input electrical pulse duration also goes up. To achieve this, a pulse forming network (PFN) based Marx generator is proposed. The Bipolar Marx generator is preferred over the uni-polar Marx generator to obtain the high voltage high current pulse. This also helps in maintaining the impedance requirement for Backward Wave Oscillator (BWO) devices that generate the microwave pulse. To the best of our knowledge, PFN based Marx generators have been developed up to 400 kV. Here, a bipolar Marx generator has been designed with ratings of 800 kV peak voltage, 10 kA peak current, and 150 ns flattop pulse duration. The design includes analytical calculations and numerical analysis by electromagnetic simulation. The triggering method to get a wide triggering range has also been discussed. The design values have also been experimentally verified, and the resulting parameters were applied to a BWO to simulate the microwave power that it can produce. A peak microwave power of ∼1 GW has been observed in the particle-in-cell simulation.