Atmospheric pressure microplasmas

Atmospheric pressure plasmas, just like most other plasmas, are generated by a high electric field in a gas volume. The few free electrons which are always present in the gas, due to, for example, cosmic radiation or radioactive decay of certain isotopes, will, after a critical electric field strength has been exceeded, develop an avalanche with ionization and excitation of species. Energy gained by the hot electrons is efficiently transferred and used in the excitation and dissociation of gas molecules. In a nonequilibrium atmospheric pressure plasma, collisions and radiative processes are dominated by energy transfer by stepwise processes and three-body collisions. The dominance of these processes has allowed many 

A number of configurations of microplasma reactors will be described here. Classification will be based on the power sources, the electric field switching frequency ranging from DC to GHz, and electrode geometries and materials, extending from DBDs to micro hollow cathodes and microcavity discharges. 

and (d) 3 mm electrode spacing (Staack et al, 2005 reproduced with permission). 

The conditions for gas breakdown in an electrical field can be described in terms of the breakdown voltage as a function of the product of pressure and gap spacing. The resulting graph is known as the Paschen curve 

Simulation without field emission Experimental results Paschen s curve in atmospheric air 

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Figure 8-41. General schematic of the atmospheric-pressure microplasma jet etcher.

Microetching, Microdeposition, and Microsurface Modification by Atmospheric-Pressure Microplasma Discharges... 

Staack, D. (2008), Atmospheric Pressure Microplasmas and Their Application to Thin Film Deposition, PhD. 

Lee, H.J., et al. Degradation of adhesion molecules of G361 melanoma cells by a non-thermal atmospheric pressure microplasma. New Journal of Physics 11, 115026 (2009)... 

Evju JK et al (2004) Atmospheric pressure microplasmas for modifying sealed microfluidic devices. Appl Phys Lett 84(10) 1668-1670... 

Yoshiki, H. Abe, K. Mitsui, T. (2006). SiCh thin film deposition on the inner surface of a poly(tetra-fluoroethylene) narrow tube by atmospheric pressure glow microplasma. Thin Solid Films, VoL 515, pp. 1394-1399 Yoshiki, H. Mitsui, T. (2008).TiO2 thin film coating on a capillary inner surface using atmospheric-pressure microplasma. Surf Coat Technol, Vol. 202, pp. 5266-5270... 

Yoshiki, H. Saito, T. (2008). Preparation of Ti02 thin films on the inner surface of a quartz tube using atmospheric-pressure microplasma. /. Vac. Sci. Technol A, Vol. 26, 338-343... 

Detavemier, C., Dendooven, J., Sree, S.P., Ludwig, K.F., Martens, J.A., 2011. Tailoring nanoporous materials by atomic layer deposition. Chem. Soc. Rev. 40, 5242—5253. Dobbs, H.S., 1982. Fracture of titanium orthopaedic implants. J. Mater. Sci. 17, 2398—2404. Doherty, K.G., Oh, J.-S., Unsworth, P., Bowfield, A., Sheridan, C.M., Weightman, P., Bradley, J.W., Williams, R.L., 2013. Polystyrene surface modification for localized cell culture using a capillary dielectric barrier discharge atmospheric-pressure microplasma jet. Plasma Processes Polym. 10, 978—989. 

Through the generation of highly reactive species such as energetic electrons and active radicals, microplasma reactors create novel process windows for C-C and C-H bond cleavage involved in the decomposition of harmful gaseous pollutants at atmospheric pressure. As an example of... 

Although mainly used for liquid samples where the solution is nebulised into the plasma, solids can be introduced directly in the case of laser-produced plasmas. The microplasma is produced at atmospheric pressure and laser ablation of the sample occurs. Fine particles are taken up by a sdeam of argon for further volatilisation, atomisation and ionisation in the ICP. 

Plasma jet Study of the ionic species in the plume of atmospheric-pressure helium microplasma Oh et al. [363]... 

Oh, J.-S., Aranda-Gonzalvo, Y., Bradley, J.W. (2011) Time-resolved Mass Spectroscopic Studies of an Atmospheric-pressure Helium Microplasma Jet. J. Phys. D Appl. Phys. 44 365202. 

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