Nanosecond Near-Spinodal Homogeneous Boiling of Water Superheated by Pulsed CO/sub 2/ Laser

Abstract

The fast boiling dynamics of superheated surface layers of bulk water cavitating under near-spinodal conditions during nanosecond C O2 laser heating pulses was studied using contact broad-band photoacoustic spectroscopy. Characteristic pressure-tension cycles recorded by an acoustic transducer at different incident laser fluences represent (a) weak random oscillations of transient nanometer-sized near-critical bubbles-precursors and (b) well-defined stimulated oscillations of micron-sized supercritical bubbles and their submicrosecond coalescence products. These findings provide an important insight into basic thermodynamic parameters, spatial and temporal scales of bubble nucleation during explosive liquid/vapor transformations in absorbing liquids ablated by short laser pulses in the thermal confinement regime. © 2007 The American Physical Society