Effect of the angle between the electric field and the gas flow one on the plasma plume dynamics at atmospheric pressure

Abstract

A novel argon plasma jet driven by an alternating current voltage is developed to generate atmospheric pressure plasma plume in the downstream region of a rod electrode. The novel jet is neither a linear-field jet, nor a cross-field jet, whose angle between the electric field and the flow one can be changed easily. Result indicates that the downstream plume length decreases with increasing the angle under constant peak voltage. For different angles, the positive discharge or the negative one per half voltage cycle corresponds to a discharge pulse. Moreover, the pulse intensity decreases with increasing the angle. By fast photography, the effect of the angle is investigated on the discharge dynamics of the plasma plume. It is found that every discharge pulse corresponds to the propagating process of a plasma bullet. The bullet velocity increases firstly, then decreases during its propagating process. Moreover, its maximal velocity decreases with increasing the angle. Based on the Collisional-Radiation model, the intensity ratio of two spectral lines is investigated to obtain the spatial distribution of excited electron temperature, which corresponds to the spatial distribution of net electric field. Result suggests that the spatial distribution of the net electric field is similar with that of the bullet velocity.