15 January 2009

Study of Laser Induced Breakdown in Water Suspensions

Written by Jane Levinson

Jane Levinson, Valery Bulatov, Gregory Toker, Vladimir Gridin, and Israel Schechter

In this study we attempted to characterize the discharge phenomenon in water suspensions and to understand the results. The Laser interaction with matter results in a breakdown process which brings to plasma formation. The spatial distribution of the induced plasma in suspensions was compared to that obtained in pure water. Such data were obtained from plasma imaging. Both silica and polystyrene suspensions were examined. The size distribution of the waterborne particulates affects the breakdown threshold. This can be utilized for estimating sizes. Simple models can explain the size and concentration effects. The results obtained with laser irradiation at 1064 nm were compared to those at 532 nm, and it was found that the laser wavelength affects the plasma imaging. The 1064 nm excitation resulted in significantly higher breakdown threshold. Simultaneous sampling was performed by combining both wavelengths. The results indicate possible application of this method to characterization of suspensions.