Characterization of stable brush-shaped large-volume plasma generated at ambient air

Abstract

A brush-shaped, large-volume plasma was generated at ambient pressure with a dc power supply and flowing argon gas, as well as a narrow outlet slit. Based on the V–I curve and emission profiles obtained in our experiment, the plasma shows some typical glow discharge characteristics. The electron density in the positive column close to the anode is about 1.4×1014cm-3 high, which is desirable for generating abundant amounts of reactive species in the plasma. Emission spectroscopy diagnosis indicates that many reactive species, such as excited argon atoms, excited oxygen atoms, excited nitrogen molecules, OH and C2 radicals, etc., generated within the plasma are distributed symmetrically and uniformly, which is preferable to some chemical reactions in practical applications. Spectral measurement also shows that the concentration of some excited argon atoms increases with the argon flow rate when the applied voltage is unvaried, while that of these excited argon atoms declines with the discharge current in the normal/subnormal glow discharge mode with the argon flow rate fixed. The plasma size is about 15 mm × 1 mm × 19 mm (L, W, H), when 38-W of discharge power is used. Such a laminar brush-shaped large-volume plasma device ensures not only efficient utilization of the plasma gas, but also effective processing of objects with large volume and complicated structure that are susceptible to high temperatures.