Space charge-what it is, how it is measured and why measure it?

The problem of how to measure actual charge distributions, and in particular space charge distributions, in cables and other insulated systems is considered. Two techniques have been developed. Both make use of applying a force pulse to the sample which disturbs the equilibrium charge distribution and hence generates a change in the plate charge which can be detected and amplified. Examples of experimental determination of charge distributions in polymeric samples, and the analyses of these in terms of charge densities and mobilities, are presented