Experiments on spatial emission distribution in an Ar atmospheric pressure plasma jet stream

Atmospheric pressure plasma is expected to contribute towards continuous treatment and processing speed improvement of surface treatment. Therefore, it is important to know the distribution condition of the radicals in the atmospheric pressure plasma. The knowledge in the distribution condition of the radicals in plasma is useful for future application of this type of plasma. In this work, the radicals of Ar atmospheric pressure plasma had been measured. This atmospheric pressure plasma generating device is constructed with a silica glass pipe partially inserted into a copper pipe which is an electric discharge electrode. The exposed silica glass pipe is covered with a copper foil which acts as a grounding electrode. There is 1 mm distance between the electrodes, and 10 kV, 10 kHz voltage is applied to generate dielectric barrier discharge (DBD). In addition, carrier gas Ar is supplied there so the plasma is generated and streamed from the silica glass pipe to the air. This plasma is diagnosed using emission spectroscopy method. The measurements were done in 3 dimensions where x-axis was the horizontal direction and y-axis was the perpendicular direction from the frontal view of the silica glass pipe. The z-axis was the distance from the edge of the silica glass. From the results of the radical distribution measurement, the spatial emission spectrum of Ar, OH, N₂ and O were visualized.