Progress in space charge measurement techniques and their industrial applications

Space charge measurement has become a common method of investigating the properties of solid dielectrics. The pulsed electroacoustic method is one of the acoustic+ techniques and has been used in various industries. The first application was in the evaluation of high voltage insulations, particularly of dc cables. The observed space charge profiles satisfactorily explained some peculiar phenomena, and at the same time, generate challenging issues, such as ´ charge packets´ travelling between electrodes. In the last decade, it has been recognised that the space charge measurement is extremely useful in the photocopier and power electronics industries. With the improvement of the spatial and time resolutions of space charge measurement, not only engineers but also physicists now use experimental data to explain conduction and breakdown phenomena in solid dielectrics theoretically. Progress in the measurement method has expanded the range of applications, and has revealed interesting new topics in research of solid dielectrics.