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Near-Field Thermal Radiative Transfer And Thermoacoustic Effects From Vapor Plumes Produced By Pulsed Co/Sub 2 /Laser Ablation Of Bulk Water, S. I. Kudryashov, Kevin Lyon, S. D. Allen

Mechanical Engineering - Daytona Beach

Submillimeter deep heating of bulk water by thermal radiation from ablative water plumes produced by a 10.6 μm transversely excited atmospheric C O2 laser and the related acoustic generation has been studied using a contact time-resolved photoacoustic technique. Effective penetration depths of thermal radiation in water were measured as a function of incident laser fluence and the corresponding plume temperatures were estimated. The near-field thermal and thermoacoustic effects of thermal radiation in laser-ablated bulk water and their potential near-field implications are discussed.

c 2006 American Institute of Physics

Submicrosecond Dynamics Of Water Explosive Boiling And Lift-Off From Laser-Heated Silicon Surfaces, S. I. Kudryashov, S. D. Allen

Mechanical Engineering - Daytona Beach

Explosive boiling and lift-off of a thin layer of micron-sized transparent water droplets from an absorbing Si substrate heated by a nanosecond KrF laser were studied using a contact photoacoustic technique. The compressive photoacoustic response increases steeply to an asymptotic value on the order of the water critical pressure starting at a threshold laser fluence of 0.20 J cm2, where lift-off of the water layer also occurs. Above this threshold, several reproducible discrete multimegahertz components are revealed in Fourier spectra of the acoustic transients, corresponding to nanosecond oscillations of steam bubbles inside the water droplets on the microsecond time scale …

Parametric Generation Of Multimegahertz Acoustic Oscillations In Laser-Generated Multibubble System In Bulk Water, Sergey I. Kudryashov, Kevin Lyon, Susan D. Allen

Mechanical Engineering - Daytona Beach

Using a nanosecond C O2 laser for explosive surface boiling of bulk water, oscillatory acoustic transients from steam bubbles were recorded using a contact photoacoustic technique. Multiple well-resolved, high-amplitude multimegahertz spectral features reflecting parametric interactions between oscillations of cavitating steam bubbles were revealed in the fast Fourier transformation spectra of these transients. A potential parametric generation mechanism for these oscillation modes of steam bubbles is discussed.

© 2006 American Institute of Physics.

Photoacoustic Study Of Krf Laser Heating Of Si: Implications For Laser Particle Removal, Sergey I. Kudryashov, Susan D. Allen

Mechanical Engineering - Daytona Beach

A photoacoustic study of KrF laser heating of Si has revealed that the dominant mechanism of acoustic generation is thermoacoustic with a considerable contribution from the concentration-deformation mechanism at laser fluences below the Si melting threshold of 0.5 J/cm ². Upon Si melting the contraction of the molten material contributes significantly to acoustic generation. At fluences above 1.4 J/cm ² laser ablation of the molten layer enhances the amplitude of the compression pulse and diminishes that of the rarefaction pulse. The results of photoacoustic measurements allow optimization of experimental conditions for dry laser particle removal.

© 2002 American Institute …