ACOUSTIC PROBING: A NEW METHOD OF MEASURING THE ELECTRICAL CHARGE AND FIELD IN THE VOLUME OF DIELECTRICS.

In the investigations and practical use of various dielectric materials, it is important to take account of, and make quantitative estimates of, electrical changes in their volume. The appearance or significant variation of electrical, mechanical, or radiational perturbation is especially important in the engineering use of dielectrics. The quality of investigation in this field of dielectric physics is related to the possibilities of experimental determination of electric quantities in the volume of materials; therefore, various measurement methods for volume electrical quantities have been developed. In the USSR and elsewhere, there has recently been considerable development of methods of probing the electrical potential, field, and charge using traveling mechanical waves. In 1979, waves in the form of short pulses excited by means of a laser (acoustic zone) were used to probe electrical fields. Subsequently, these principles (a step strain wave and a short pulse) were used by various researchers. Methods using a laser to excite mechanical waves are widespread at present. In the present work, the physical principles of the acoustic-probing method are outlined, experience in practical use of the method is generalized, and its potential and prospects for development are evaluated.