A tomographic visualization of electric discharge sound fields in atmospheric pressure plasma using laser diffraction ^*

¹ Graduate School of Industrial Engineering, Tokai University, 9-1-1 Toroku Higashi-ku, Kumamoto 862-865, Japan
² Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami Chuo-ku, Kumamoto 860-0082, Japan
³ Institute of Electrical Engineering and Electrotechnology, Faculty of Electrical Engineering and Computer Science, Lublin University of Technology, 38A Nadbystrzycka str., 20-618 Lublin, Poland

^a e-mail: nakamiya@tokai.ac.jp

Received: 29 September 2012
Revised: 2 November 2012
Accepted: 5 December 2012
Published online: 18 February 2013

Abstract

The phase modulation of transparent gas can be detected using Fraunhofer diffraction technique, which we call optical wave microphone (OWM). The OWM is suitable for the detection of sonic wave from audible sound to ultrasonic wave. Because this technique has no influence on sound field or electric field during the measurement, we have applied it to the sound detection for the electric discharges. There is almost no research paper that uses the discharge sound to examine the electrical discharge phenomenon. Two-dimensional visualization of the sound field using the OWM is also possible when the computerized tomography (CT) is combined. In this work, coplanar dielectric barrier discharge sin different gases of Ar, N₂, He were characterized via the OWM as well as applied voltage and discharge current. This is the first report to investigate the influence of the type of the atmospheric gas on the two-dimensional sound field distribution for the coplanar dielectric barrier discharge using the OWM with CT.