Imaging gas and plasma interactions in the surface-chemical modification of polymers using micro-plasma jets

Abstract

This paper reports on the correlation between gas flow and plasma behaviour in the outflow of a micro-atmospheric pressure plasma jet operating in helium using both 2D optical imaging and Schlieren photography. Schlieren photography shows that the helium outflow changes from laminar to turbulent conditions after distances between 20 and 50 mm from the nozzle. Above a flow rate of 1.4 slm, the length of the laminar region decreases with increasing flow rate. However, by contrast the visible plasma plume increases in length with increasing flow rate until its extension just exceeds that of the laminar region. At this point, the plasma becomes turbulent and its length decreases. Exposing polystyrene (PS) samples to the plasma jet significantly alters the water contact angle in a defined area, with the hydrophobic PS surface becoming more hydrophilic. This modification occurs both with and without direct contact of the visible glow on the surface. The radius of the treated area is much larger than the width of the visible jet but much smaller than the area of the turbulence on the surface. The treated area reduces with increasing nozzle–substrate distance.

Effectiveness of jet location on mixing characteristics inside a cavity in supersonic flow

“…1, where γ is the specific heat ratio, ρ is the density, M is the Mach number and subscripts 0 and jet refer to freestream and jet conditions. Schlieren photography [40][41][42][43][44] was employed to visualize the flow field around the cavity in a standard Z-type optical arrangement. A pair of 203.3 mm diameter parabolic mirrors with 1016 mm focal length and a 150W Hamamatsu Xenon continuous light source were used.…”

Jet‐to‐jet interactions in atmospheric‐pressure plasma jet arrays for surface processing

“…Therefore, APPJ is suitable for potential applications in materials processing, plasma biomedicine, surface decontamination, and thin film deposition. [5][6][7][8][9] However, the treatment area of a typical single plasma jet is less than 1 cm 2 due to the confinement of the structure of the plasma jet devices. This is one important factor to limit the applications of APPJ.…”

Plasma actuator: Influence of dielectric surface temperature

“…1,2 In the past ten years single dielectric barrier discharge (SDBD) actuators have shown remarkable promise for various flow control applications. The benefit of converting electrical energy into kinetic energy without the need for any moving parts, having near instantaneous response, consuming relatively low power, and a wide range of operational frequencies have made these devices an attractive alternative to other active flow control methods such as piezoelectric actuators, synthetic jets, and vortex generators.…”