Now showing 1 - 3 of 3
  • Publication
    Atmospheric pressure plasma acoustic moment analysis
    (American Institute of Physics, 2011) ; ;
    Low-order moment around the mean (mean, standard deviation and skewness) analysis of the time evolving specific acoustic intensity of an air atmospheric pressure plasma jet is performed as a function of nozzle-to-surface gap (0.5 to 7 cm), drive frequency (19, 22, and 25 kHz) and air flow rate (35.7 to 76.6 l/m). The probability distribution of each time-series dataset exhibits deterministic correlations with contrasting entropy process regions afterglow (blown arc process (gap = 0.5 cm and 1740 ±100 K); and gap = 1 to 7 cm and 300 to 400 K)). The results indicate that the heated air is channeled along the surface and has a preferred backscatter an ular. In addition the blown arc process exhibits a skewness of +0.055 and the afterglow has skewness values from -0.05 to -0.4. These results illustrate how acoustic information can be used to differentiate plasma-surface entropy states.
      515
  • Publication
    Resonances and patterns within the kINPen-MED atmospheric pressure plasma jet
    The kINPen MED atmospheric pressure plasma jet is now undergoing clinical studies that are designed to investigate its suitability as a device for use in plasma medicine treatments. This paper describes dimensionless studies of the synchronizing oscillatory gas flow through the nozzle followed by electro-acoustic measurements coupled with the discharge photo emission. The plasma jet operates in the burst mode of 2.5 KHz (duty cycle = 50%), within a neutral argon Strouhal number of 0.14 to 0.09 and Reynolds number of 3570 to 5370. In this mode the jet acts like a plasma actuator with an anisotropic far field noise pattern that is composed of radiated noise centered at 17.5 kHz; +20 dB, and the expanding visible plasma plume and cooled gas recombine along the jet axial flow (1-2 kHz peak that diminishes at a rate of -1.7 dB.kHz-1).
      822
  • Publication
    Influence of dc Pulsed Atmospheric Pressure Plasma Jet Processing Conditions on Polymer Activation
    Plasma treatments are widely used to activate polymer surfaces prior to adhesive bonding. This study investigates the influence of plasma treatment conditions on the surface activation of a range of polymers using the PlasmaTreat (Open Air) system. In this study the effect of dc pulse plasma cycle time, compressed air flow rate and the plasma jet nozzle to substrate distance on the plasma discharge was examined. The influence that the dc pulse plasma cycle time parameter has on the activation of polypropylene, polystyrene and polycarbonate was also investigated. The level of polymer surface activation was evaluated based on the change in water contact angle after plasma treatment. The polymer surface properties were also monitored using AFM and XPS measurements. The heating effect of the plasma was monitored using both infrared thermographic camera and thermocouple measurements. Plasma diagnostics measurements were obtained using the photo-diode and optical emission spectroscopy techniques. From this study it was concluded that for the PlasmaTreat system the level of plasma activation was closely correlated with the dc pulsed plasma cycle time, which is a measure of the plasma intensity. For example, the more intense plasma obtained with shorter cycle times gave higher levels of polymer activation. The optimized pulsed plasma cycle times were found to be specific for a given polymer type and related to their thermal properties. The pulsed cycle times were also found to correlate with both the substrate and plasma gas temperatures.
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