Investigation of the electrosprayed water microdroplets using optical imaging methods
Hassan M. E., Janda M., Machala Z.,
22nd Symposium on Application of Plasma Processes and 11th EU-Japan Joint Symposium on Plasma Processing SAPP XXII, Štrbské Pleso, January 18-24, p. 330-334 (2019)
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Abstract: An electrostatic spray (ES) of liquids is a simple way to generate microdroplets with high surface-to-volume ratio. The ES generated by electrical discharges enables a fast transfer of reactive species from plasma into the liquid for an efficient generation of plasma activated water. Here we present a relatively simple, versatile, and cost-effective diagnostic technique for online monitoring of ES microdroplets that enables simultaneous and synchronized electrical and optical diagnostics of an electrical discharge. This technique is based on the planar laser light attenuation monitored by a large area photo-detector covered by a slit. Two variants were tested and compared – one with two lasers and another with one laser and a broadband LED lamp. This technique enables estimations of the speed and size of microdroplets (down to ~10 μm) and allows for monitoring the dripping frequency or studying fragmentation of microdroplets and water filaments. The ES characteristics obtained by this technique were successfully verified by ultra high-speed camera imaging.
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