Investigation of Cold Atmospheric Pressure Plasma at Radio-frequency 13.56 MHZ

In this study we designed an RF plasma circuit. By using argon as plasma-forming gas, we investigated argon cold plasma plume at atmospheric pressure. Due to the tendency of transferring into arc mode after gas breakdown, resulting from the avalanche of electrons, we employed a glass tube as a dielectric barrier layer to inhibit the occurrence of the arc mode. We used an RF power supply at frequency 13.56 MHZ, working with 300W output-input impedance. In order to recognize plasma, optical emission spectroscopy (OES) apparatus was used. Oxygen, argon, copper and nitrogen spectrum lines were diagnosed. Since the study of discharge modes is important to the specific requirement of their intended applications, we investigated the plasma ignition mode. To do this, the discharge images were taken by a digital camera and colour codes of the images were changed to the relative intensity distribution.