Influence of High-Voltage Electrode Arrangement on Downstream Uniformity of Jet Array

Atmospheric-pressure plasma jet (APPJ) array could effectively enlarge the treatment area for the requirement of application efficiency. The downstream uniformity of jet array is the determinant for the even processing effect. In this paper, a three-jet 1-D APPJ array with the electrode structure of needle-ring is constructed, and the position of needle electrode (high-voltage electrode) is adjusted to investigate the influence of electrode arrangement on the downstream uniformity of the 1-D APPJ array. The results show that the relative difference of the positions of the middle and side needle electrodes d has great influence on the downstream uniformity. When the distances of the middle and side needle electrodes to the tube nozzles a and b are both fixed at 40 mm (d = 0 mm), the middle plume is suppressed. With increasing the distance of the side needle electrodes to the tube nozzles b to make d = 1, 2, and 3 mm, the middle plume is prolonged and the lengths of all plumes are almost equal at d = 2 mm. With the intensified charge-coupled device (ICCD) image measurement, it is found that the desirable synchronicity of bullets propagation is obtained at d = 2 mm. The electrical field distributions of different d are simulated, which can be seen that the high electric fields of the side jets can suppress the propagation of middle jet and at d = 2 mm, the three jets have similar maximum values of the electrical field strength along the direction of needle electrode resulting in similar plume lengths in the APPJ array.