Marx-generator design and development for biomass electroporation

Abstract

In 1923, Erwin Marx invented a pulse generator based on a capacitor discharge, now known as Marx generator. Capacitors are charged in parallel connection and discharged in series connection for voltage multiplication. The arrangement of components enables a design, for which each element of the generator needs to be designed for no higher voltage than the charging voltage per stage. Originally, the Marx generator has been designed for high-voltage testing. In recent years, Marx generators have been developed for the treatment of biological tissue by pulsed electric fields (PEF). In contrast to Marx generators for high-voltage testing, these generators are operated continuously at a repetition rate of at least 20 Hz. Generators for high pulsed power applications might be set up using charging coils and spark gap switches. Spark gap switches for extended lifetime have been developed based on electrodes made of tungsten copper alloy and machined with a homogeneous field profile. For triggered long-term operation, overvoltage triggering in combination with artificial seed electron generation by means of a corona discharge is applied. For another design, the use of semiconductor switches enables the generation of rectangular or stepwise arbitrary waveforms. Selected circuits for semiconductor-based Marx generators for generating positive, negative, and bipolar voltage shapes are described.