Investigation Methods and Techniques for Plasma Characterisation in a Spark Gap Model at Surge Currents - a Review

Plasma are an often used element in AC- and DC-circuit breakers as well as in class I surge protective devices. In order to understand the behaviour of the devices it is necessary to understand the plasma behaviour. Thus the plasma has to be characterised. In AC- and DC-circuit breakers the plasma is already well investigated. But for plasma in surge protective devices and therefore at surge currents the characterisation of the behaviour is done only in the last few years. In this publication a review of different methods for this characterisation is given. These methods are useable for the investigation of the current, voltage, propagation, electrical conductivity, pressure and temperature of the plasma. For each method the measuring principle, the requirements, an exemplary set-up as wells as first results are given.