Dielectric Materials for Electrical Engineering

Chapter 11

Pulsed Electroacoustic Method: Evolution and Development Perspectives for Space Charge Measurement 1

11.1. Introduction

The presence of space charges (SC) in materials is a phenomenon which has been studied for many years [IED 84], [SES 97]. However, understanding of the generation, transport, and trapping modes of these charges has not yet been achieved. Amongst the numerous techniques developed to detect the presence of SC in materials [TAK 99], this chapter focuses on the pulsed electroacoustic (PEA) method.

During the past 20 years, much progress has been made concerning charge distribution detection in dielectrics through this technique. How this method is performed is in constant evolution, but the operating principle, which will be described in this chapter, remains unchanged [MAE 88].

In the first part of the chapter, we will endeavor to describe the general operating mode of the PEA system, and then, in part two, we shall list the diverse assemblies developed for specific applications. We shall outline the current systems’ limits and also the development perspectives that they open in diverse application areas.

11.2. Principle of the method

11.2.1. General context

The charges which accumulate during the application of an external excitation (electric field, irradiation, etc.) modify the material’s internal electric field and can cause an electrical breakdown in certain cases. The charges accumulation has been studied for a long time by techniques capable of ...