Propagation of Brush-Shaped He/O2 Plasma Plumes in Ambient Air

In this paper, we report on the propagation behavior of the atmospheric-pressure and brush-shaped He/O₂ plasma plumes generated by a specially designed plasma device. The measurements show that the frequency of applied voltage (f) and the O₂ fraction and flow rate of the feed gas significantly affect the discharge propagation of the atmospheric-pressure plasma plume in ambient air. The uniformity of the brush-shaped plasma plume is greatly improved at a relatively high f or He/O₂ flow rate. Addition of a trace amount of O₂ into the He gas can also contribute to the formation of uniform and brush-shaped plasma plumes in ambient air. This paper confirms that the plasma device composed of well-aligned and micrometer-thick fibers can be utilized to generate large-scale plasma plumes for potential applications. The propagation of the He/O₂ plasma plume in ambient air results from the applied electric field across the small gas spacing of a barrier discharge electrode configuration, where the He atoms are easily ionized or excited for generating the brush-shaped plasma.