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Plasma Created in High-Frequency Electromagnetic Fields
Published in Alexander Fridman, Lawrence A. Kennedy, Plasma Physics and Engineering, 2021
Alexander Fridman, Lawrence A. Kennedy
Thermal atmospheric pressure plasma can be generated by optical radiation somewhat similar to the way it is generated by electromagnetic waves in the RF and microwave frequency range. These not so conventional but very interesting thermal plasma generators were first theoretically considered by Yu.P. Raizer (1970), and then experimentally realized by N.A. Generalov, V.P. Zimakov, G.I. Kozlov, V.A. Masyukov, Yu.P. Raizer (1970). Optical plasma generation began before 1970 with the discovery of the optical breakdown effect (P.D. Maker, R.W. Terhune, C.M. Savage, 1964). It became possible after the development of Q-switched lasers, which are able to produce extremely powerful light pulses, the so-called “giant pulses”. Detailed consideration of the subject can be found in the book of Yu.P. Raizer (1974); typical breakdown thresholds are presented in Figure 10.16 (Yu.P. Raizer, 1977). The continuous optical discharge is illustrated in Figure 10.17. Usually, a CO2 laser beam is focused by a lens or mirror to sustain the discharge. Power of the CO2 laser should be high; for the continuous optical discharge in atmospheric air it must be at least 5 kW in the low-divergence beam. To sustain the discharge in xenon at pressure of a couple of atmospheres, much lower power of approximately 150 W is sufficient.
Surface-engineered silicon nanocrystals
Published in Klaus D. Sattler, Silicon Nanomaterials Sourcebook, 2017
Calum McDonald, Tamilselvan Velusamy, Davide Mariotti, Vladimir Svrcek
In this section, the surface functionalization of freestanding SiNCs in liquid media by atmospheric pressure microplasma will be presented. This type of surface engineering can be carried out during or post synthesis, while wet-chemical methods like hydrosilylation are mostly performed post synthesis. In this technique, the surface engineering of nanocrystals is carried out directly in a colloid, where the liquid media can be a wide range of solvents yielding different surface chemistries; however, this chapter will focus on the surface engineering in ethanol and water. A chemically active surface is required for plasma–liquid surface engineering, for example, Si–H, Si–OH, Si–Cl terminations, and the starting surface termination can determine the type of engineering achieved. Si–H terminations can be readily achieved following synthesis via electrochemical etching in hydrofluoric acid. Three main methods have been developed for surface engineering by atmospheric pressure plasma in liquid media; pulsed laser processes, direct-current (DC) plasma, and ultrahigh frequency (UHF) plasma.54
Low-Temperature Plasma-Enhanced Chemical Vapor Deposition of Silica-Based Membranes
Published in Stephen Gray, Toshinori Tsuru, Yoram Cohen, Woei-Jye Lau, Advanced Materials for Membrane Fabrication and Modification, 2018
Hiroki Nagasawa, Toshinori Tsuru
Recently, atmospheric-pressure plasma has emerged as a new plasma source (Tendero et al., 2006; Massines et al., 2012). The most important advantage of atmospheric-pressure plasma is that a stable discharge can be easily obtained without a vacuum system. This makes atmospheric-pressure processes more versatile than those under a vacuum. It can be operated in open-air as well as in-line processes. Regarding the application in membrane fabrication, atmospheric-pressure plasma processing can contribute to the fabrication of membranes in a continuous process for large-scale manufacturing. One option for preparing inorganic membranes via plasma-based route at atmospheric pressure is the use of atmospheric plasma spraying technique, which uses a high-temperature plasma jet at temperatures of the order of 10,000 K (Tung et al., 2009; Lin et al., 2012). In the atmospheric plasma spraying technique, ceramic and metal particles are fed into and melted in the high-temperature plasma jet, and then precipitated onto a substrate to form a solid alloy or ceramic coating. Tung et al. (2009) prepared ceramic-metallic microfiltration membranes with a pore size of 0.2-0.4 μm using α-Al2O3 particles with Ni and Cr as metal binders. They also synthesized photocatalytic TiO2 membranes with a pore size of 0.35 μm that could be used to treat water through photodegradation of organisms and proteins under UV irradiation (Lin et al., 2012). An attempt to use high-temperature plasma to prepare gas separation membranes was made by Chen and co-workers (2013). They modified poly(dimethylsiloxane) membranes using high-temperature plasma to form a permselective SiOx layer on the membrane surface. Such high-temperature plasma techniques are suitable for fabricating fully inorganic membranes but cannot be used to produce organic-inorganic hybrid membranes.
Bactericidal efficiency of silver nanoparticles deposited on polyester fabric using atmospheric pressure plasma jet system
Published in The Journal of The Textile Institute, 2022
Giovanni M. Malapit, Ronan Q. Baculi
Plasma is an assemblage of free charged particles and neutrals in random motion which are, on the average, electrically neutral (Brown, 2004; Lieberman & Lichtenberg, 1994). This dynamic mix of neutrals, ions, electrons and even photons, radicals, excited species, molecular and polymeric fragments contribute in the functionalization of material surfaces with minimal effect to the whole properties of the materials (Ocampo et al., 2018; Shishoo, 2007). While thermal plasmas are mostly applied for metal hardening and surface cleaning, non-thermal equilibrium plasmas or cold plasmas are fitting candidates for nanoscale surface modification of natural or synthetic polymeric materials such as textiles. Cold plasmas are characterized by having electrons with relatively high temperature but their atomic and molecular species are at near ambient temperature making them suitable for pre-treatment and finishing of textile fabrics without affecting their bulk properties (Hong & Sun, 2008). Non-thermal plasma was generated in this work using a novel atmospheric pressure plasma jet (APPJ) system. This device produces low-pressure plasma with temperatures from 25 to 200 °C that can be used for materials processing. Single gases or mixture of gases flow through a pair of electrodes encapsulated by a glass tube. High voltage from a neon sign transformer is applied to the electrodes to form a glow discharge and with the flow of gases, the plasma discharge is plumed out of the nozzle (Ocampo et al., 2018).
Effect of vacuum–ultraviolet irradiation in a nitrogen gas atmosphere on the adhesive bonding of carbon-fiber-reinforced polyphenylene sulfide composites
Published in The Journal of Adhesion, 2022
S. Kawasaki, Y. Ishida, T. Ogasawara
Corona, plasma, flame chemical vapor deposition, and ultraviolet (UV)/ozone treatments have been studied as physical surface treatment technologies.[9, 10, 11, 12, 13, 16] Kruse et al. have reported that oxygen and argon plasmas are effective for the improvement in PEEK adhesive strength.[9] However, the low-pressure plasma processing requires a low-pressure environment. Therefore, it is difficult to introduce it to a production line and to apply it to large components. The atmospheric-pressure plasma treatment is expected to be used in industrial applications because it does not require low-pressure environment. Iqbal et al. have reported that the atmospheric-pressure plasma treatment is more effective than the low-pressure plasma treatment in terms of surface energy and bonding strength for FRTPs.[4] J. Muñoz et al. investigated the effectivity for distances of the atmospheric-pressure postdischarge treatment. They reported that the treatment is effective up to a distance of 5 cm.[17]
Optimization and surface modification of silk fabric using DBD air plasma for improving wicking properties
Published in The Journal of The Textile Institute, 2018
K. Vinisha Rani, Nisha Chandwani, Purvi Kikani, S. K. Nema, Arun Kumar Sarma, Bornali Sarma
Dielectric barrier discharge (DBD) is a cold, non-equilibrium, atmospheric pressure plasma has been used in many industrial applications including the textiles department for surface modifications (Sarmadi, 2013). DBD plasma can be used in the textile material to alter the surface properties of the fabrics. Plasma treatment has advantages when compared to the conventional wet chemical process in terms of reduction of waste and contamination problems and time (Hegemann, 2006). The plasma treatment on silk fabrics is a dry clean and eco-friendly process (Iriyama et al., 2002). Plasma treatment on silk fabrics changes only the uppermost atomic surface layers of the fabric, while bulk properties are unaffected due to low range of penetrations (Sparavigna, 2008). Atmospheric pressure plasma is used for changing the surface functionalities like hydrophobic to hydrophilic (Samanta, Joshi, Jassal, & Agrawal, 2012). Introducing polar groups onto the fiber surface can increase the hydrophilicity (Morent et al., 2008). Plasma treatment modifies the physicochemical properties of the fabric surface (Inbakumar & Anukaliani, 2009).