Basic concepts of high-voltage pulse generation

Abstract

For electroporation experiments it is essential to generate, in a controlled way, repetitive high-voltage pulses, with precise voltage amplitude and pulse widths, in order to deliver well-defined energy packages to biologic loads. This transient energy flow can be based on relatively simple circuits consisting of passive discrete resistive-inductive-capacitive elements, transformers or transmission lines, and switches, which convert the energy stored in the electric fields of capacitors or magnetic fields of coils into well-defined voltage pulses. Here, transient phenomena of single and stack circuits are described as a basis of the generation and handling of high-voltage pulses, which are described elsewhere in this handbook. These include direct capacitive discharge, comprising a single switch or an association of circuits to circumvent the still voltage and current limitation of semiconductors, which include adder and Marx generator circuits. The use of a single step-up transformer or inductive adder circuit will be described also. Also, the utilization of transmission lines to generate and format pulses into well-defined loads is explained. In addition, the use of inductive storage with normally closed switches is presented. Finally, an example of the techniques that use resonant circuits with saturable inductor or transformer is outlined. As the behavior of the load can influence greatly the shape of the voltage pulse applied to the load as well as the current requirements of the switches, during this chapter, the type of load will be evaluated in relation to the most common type of biological type loads, with resistive or capacitive behavior, respectively.