Photoconductive switching for pulsed high-voltage generators

Abstract

High-voltage (HV) ultrashort pulse technologies require adjustable pulse parameters such as duration, amplitude, shape, number of pulses, and the frequency rate. Generators that can produce powerful electrical pulses with adjustable characteristics are convenient but still not widely available. This chapter presents a summary of key developments around HV pulse generators built on the frozenwave- generator concept. With this concept, a microstrip or coaxial transmission line technology is used to store a bias voltage from a high-voltage source. Ultrafast optoelectronic switches integrated on the line and triggered by laser beam allow delivery of pulses into an output load. Due to their advantages, photoconductive semiconductor switches (PCSS) are used in the linear running regime. These generators can produce pulses of various shapes (rectangular, bipolar, triangular), with durations ranging from a few hundred picoseconds to a few tens of nanoseconds and with amplitudes up to tens of kV. Developed generators include two types of transmission lines based on microstrip or coaxial technology and two types of PCSS capable of switching up to 4 kVor 20 kV bias voltages. This technology has enabled generation of pulses with peak amplitudes of around 15 kV. It also allows the profiling of the pulses depending on the conditions of PCSS commutations such as energy levels, optical delays, and synchronous or asynchronous activation.