Now showing 1 - 7 of 7
  • 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.
    Scopus© Citations 71  1231
  • 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.
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  • Publication
    Converting a Microwave Oven into a Plasma Reactor: A Review
    (Hindawi, 2018-05-21) ;
    This paper reviews the use of domestic microwave ovens as plasma reactors for applications ranging from surface cleaning to pyrolysis and chemical synthesis. This review traces the developments from initial reports in the 1980s to today’s converted ovens that are used in proof-of-principle manufacture of carbon nanostructures and batch cleaning of ion implant ceramics. Information sources include the US and Korean patent office, peer-reviewed papers, and web references. It is shown that the microwave oven plasma can induce rapid heterogeneous reaction (solid to gas and liquid to gas/solid) plus the much slower plasma-induced solid state reaction (metal oxide to metal nitride). A particular focus of this review is the passive and active nature of wire aerial electrodes, igniters, and thermal/chemical plasma catalyst in the generation of atmospheric plasma. In addition to the development of the microwave oven plasma, a further aspect evaluated is the development of methodologies for calibrating the plasma reactors with respect to microwave leakage, calorimetry, surface temperature, DUV-UV content, and plasma ion densities.
    Scopus© Citations 10  288
  • Publication
    Evaluation of the sensitivity of electro-acousic measurements for process monitoring and control of an atmospheric pressure plasma jet system
    The development of non-invasive process diagnostic techniques for the control of atmospheric plasmas is a critical issue for the wider adoption of this technology. This paper evaluates the use of a frequency-domain deconvolution of an electro-acoustic emission as a means to monitor and control the plasma formed using an atmospheric pressure plasma jet (APPJ) system. The air plasma system investigated was formed using a PlasmaTreatâ„¢ OpenAir applicator. Change in the electro-acoustic signal with changes in substrate type (ceramic, steel, polymer). APPJ nozzle to substrate distance and substrate feature size were monitored. The decoding of the electro-acoustic emission yields three sub dataset that are described three separate emission mechanisms. The three emissions are associated with: the power supply fundamental drive frequency and its harmonics; the APPJ nozzle longitudinal mode acoustic emission and its odd overtones, and the acoustic surface reflection that is produced by the impedance mismatch between the discharge and the surface. Incorporating this knowledge into a LabVIEW a program facilitated the continuous deconvolution of the electro-acoustic data. This enabled the use of specific frequency band test limits to control the process the APPJ treatment process which is sensitive to both plasma processing conditions and substrate type and features. PAC Codes: 52.40.Hf, 52.70.-m, 52.77.Fv, 43.60.Vx
    Scopus© Citations 12  639
  • 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).
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  • Publication
    Process control of particle deposition systems using acoustic and electrical response signals
    The implementation of statistical quality control methods for monitoring and control of powder abrasion/deposition is of increasing importance in a manufacturing environment. For the wider adoption of both current and new powder coating technologies, quality control systems need to be developed, which are easily installed, non-invasive and work in real time. This study evaluates the use of a dual electro-acoustic and electrostatic surface-charge measurement technique as means of realising real-time process control. Simultaneous changes in the signals were obtained under both powder flow-on and -off conditions and also for edge detection of the substrate. It was discovered that the most important variables which governed changes in the acoustic response signal were due to variations in the deposition pressure and stand-off distance, whilst those for the electrostatic response signal came from changes in particle size and deposition stand-off distance. A phenomenological predictive equation was developed based on a two-level full factorial design with five variables for both response factors. The coefficients of determination, r2, for the models were 93% and 98%, respectively, with respective χ2 probability values of 99% and 99.5%. This enabled the use of specific limits for any variation of variables amongst those tested to be set up, resulting in the apparatus necessary for the development of a sensitive continuous control system. Examining variations in surface roughness with electrostatic signal was observed to show a linear relationship, decreasing at a rate of 0.19 μm per 0.01 eV, as the effective particle size of Al2O3 was increased.
    Scopus© Citations 1  382
  • Publication
    Acoustic Metrology : From Atmospheric Plasma to Solo Percussive Irish Dance
    LabVIEW software is used to decode step sequences generated by Irish light and hard shoes and bare feet. To remove the low frequency reverberation of the floor a Savitzky-Golay digital filter is used to de-convolute the percussion sound of the step sequences. Floor types and foot apparel are compared.
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