Cavitating Flow Luminescence (CFL) is spontaneous photon emission associated with hydrodynamic cavitation which occurs when a flowing liquid passes through a Venturi.1 In this work, cavitation and micro-plasma generation in a flowing liquid, using a micro-Venturi, has been investigated. A bench-top system was designed and constructed to study CFL in a variety of liquids. The system comprised a high flow, liquid handling manifold and micro-Venturi with a variety of orifice sizes ranging from 160 – 220 μm i.d. The CFL was detected for the first time on a micro-scale using a PMT. The effect of various parameters such as temperature, flow rate (a proxy for the pressure differential) and orifice diameter were investigated to optimise the system. Studies were carried out using DDW and the effect of temperature, pressure and orifice size on CFL; it was found that low temperatures and high pressures resulted in more intense CFL. The effect of re-gassing with different noble gases was investigated and resulted in a large increase in CFL. Investigations in to the effect of solute concentration on CFL were performed using dimethylsulphoxide, polyethyleneglycol-200, isopropanol, diethyleneglycol and Triton X 100 & titanium sulphate nano-particles. Solutes with low vapour pressures resulted in an increase in CFL whereas solutes with a high vapour pressure supressed CFL, due to quenching effects. Low resolution spectra were produced using bandwidth filters to identify wavelength areas of strong emission from CFL.

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