Synchronized observation of pressure wave influence on plasma–target interaction using optical wave microphone and high-speed camera

Abstract

Plasma–target interaction of atmospheric pressure plasma jet is one of the considerable things in a very wide range of biomedical applications with the transportation of reactive oxygen species. One of the most important observations on what plasma jets emit is pressure waves, which have been focused on the energic distribution of electric discharges in atmospheric pressure. A unique optical technique called an optical wave microphone works based on the Fraunhofer diffraction of laser for phase objects, and it has successfully detected shockwaves emitted by helium and argon plasma jet at the downstream of the plasma jet in the applied voltage frequency order of kilohertz. In this study, a fibered optical wave microphone and high-speed camera (Photron, FASTCAM SA1.1) were used for a synchronized investigation of pressure wave influence on the movement of fine particles caused by the needle electrode plasma jet. The plasma–target interaction was investigated through the synchronized observation with an optical wave microphone and a high-speed camera in which fine particles were used as the target for the observation of the influence of pressure waves. Experimental results show that the arrival and formation of pressure waves were strongly related to the fine particle movements at the plasma–target interaction.