Atmospheric pressure plasma jet treatment of empty and water filled microchannels*

With increasing interest in plasma activation of liquids, more refined methods of controlling the interaction between atmospheric pressure plasmas and liquids are needed.  In addition to plasma properties, achieving such control requires consistency in the properties of the plasma-liquid interface and exposure time of the liquid to the plasma (the “dose”).  One configuration to obtain this control is water flowing through channels – the area exposed to the plasma and residence time are well known and can be specified.  In this paper, we discuss results from a computational investigation of atmospheric pressure air plasmas interacting with water filled channels.  The work is performed using a 2-D plasma-hydrodynamics model nonPDPSIM [1].  Investigations were performed of dry and water filled rectangular channels (depth of a few 10s to 100s microns).  The dynamics of the surface ionization wave propagating across the channels will be discussed.  We found that the hydrophilicity of the material of the channels plays a role in the production of near-surface liquid species making the surface convex or concave.  The polarization of the water with surfaces having different shapes then affects the electric fields near the water surface.

[1] Seth A Norberg et al 2015 Plasma Sources Sci. Technol. 24 035026.