Pressure generation and measurement in the rapid vaporization of water on a pulsed-laser-heated surface

Abstract

The transient pressure generated by the interaction of short-pulsed laser light with the liquid–solid interface is studied quantitatively. A KrF excimer laser beam of tens of nanoseconds pulse duration irradiates water on a solid surface and induces rapid thermal expansion and explosive vaporization. The pressure pulses launched into water by such processes are detected experimentally by the photoacoustic probe beam deflection method and a broadband piezoelectric transducer. The peak intensities of the traveling pressure wave measured by these two methods are compared with the theoretical thermoelastic predictions. The measurements show that a compressional pressure wave packet is radiated from the water-solid interface with the peak intensity of the order of 1 MPa at laser fluences up to about 100 mJ/cm2. Simultaneous monitoring of the bubble growth kinetics by the optical specular reflectance probe has been performed. It is observed that the pressure generation is enhanced by the bubble expansion in the superheated water for laser fluences exceeding the bubble nucleation thresholds.

Explosive Boiling of Water Films Adjacent to Heated Surfaces: A Microscopic Description

“…S 2 (r) ) { 1 r e r on (r off 2 -r 2 ) 2 (r off 2 + 2r 2 -3r on 2 ) (r off 2 -r on 2 ) 3 r on < r e r off (8) Snapshots at different times during the simulations are shown in Figures 1-3. For the 6-layer system (Figure 1), the top approximately 4-5 layers vaporize from the surface in the form of individual molecules and very small clusters.…”

“…This phenomenon is central to a number of processes including eye surgery, selective killing of cells by irradiation of incorporated absorbing particles, 1 steam cleaning of surfaces, 2 and laser desorption mass spectrometry experiments of large biomolecules. [3][4][5] To understand the separation of a fluid from a laserheated substrate, optical reflectance and scattering studies 6,7 as well as photoacoustic experiments 8 have been performed. These studies and others 3,5,9 suggest that a fast explosive phase transition occurs in the fluid adjacent to the irradiated surface.…”

Nanomaterials synthesis by a novel phenomenon: The nanoscale Rayleigh-Taylor instability

“…The rapid heating of the film by absorption of short [such as nanosecond (ns)] pulse laser light is well known to lead to boiling of a low temperature fluid in contact with the film. [41][42][43] Because of the rapid heating rates, a large drop in temperature occurs on going away from the absorbing film, i.e. a large magnitude of thermal gradient…”

Structural Modifications of KrF Excimer Laser-Ablated Zirconium Correlated to the Surface and Mechanical Properties

“…Absorption coefficient for deionized water has value of 5.05 × 10 −3 /cm [16], whereas for ethanol its value is 4 × 10 −2 /cm [17]. It shows that ethanol will absorb more energy than deionized water; so, less energy will reach the target surface in case of ethanol.…”

“…Appearance of the overall ablated area is less distinct or faint as compared to the overall image of ablation spot in case of deionized water. From literature, the observed values of absorbance and absorption coefficient are 0.00086 and 5.05 × 10 −3 /cm for deionized water [16], whereas 0.0055 and 4 × 10 −2 /cm for ethanol [17]. This difference in the appearance of ablation spot is attributable to more absorption of energy (0.0055) by ethanol, then deionized water.…”