Analysis and NDT Applications of a Gas Discharge Electroacoustic Transducer

Abstract

In this study, a gas discharge electroacoustic transducer (GDEAT) based on a pulsed electric discharge in the air under atmospheric pressure has been investigated. The acoustic characteristic of GDEATs have been determined in the frequency range from 40 Hz to 4 MHz by evaluating acoustic pressure and recording amplitude–frequency characteristics of membranes. The electrothermoacoustic processes have been studied in open type gas discharge systems where the electrode space is in a direct contact with the environment. Some features of using the above-mentioned GDEATs in material nondestructive testing (NDT) have been demonstrated. It has been shown that, on the one hand, the wear of both electrodes and insulation limits the work life of transducer’s electrode system; however, on the other hand, this may lead to deposition of microparticles on the test object surface. The wear of the electrode system was evaluated quantitatively. The results of the chemical analysis of the deposited microparticles are presented. The possibility of using GDEATs for noncontact stimulation of local resonant vibrations in subsurface defects and visualizing vibrations by means of laser Doppler vibrometry is shown in the case of NDT of a glass fiber composite.