Dynamics of laser-driven shock waves in water

Abstract

Shock waves were produced in water by directing unfocused 0.4-J, 20-ns ruby (λ=0.693 μm) or 3-J, 8-ns Nd-glass (λ=1.06 μm) laser light onto the metalized surface of a thin plastic foil. The illuminated areas were 0.35 and 2.3 cm2, respectively, corresponding to laser irradiances of 52.6 and 68.4 MW cm−2. The radial propagation velocity and the profile of the generated waves have been measured via double-exposure interferometric holography and shadowgraphy. Using the obtained values of the shock velocities and the fringe shift in the interferograms, the pressure on the shock wave front, the thickness of the compressed water layer, the laser energy consumed in producing this layer, and the time required for its formation have been calculated.

Strain solitary waves in lengthy waveguides

“…Using this approach we estimated the attenuation coefficient for the initial shock wave we apply in our experiments for soliton generation. As we have previously shown in [15] the shock wave produced in water by means of laser evaporation of a metallic target immersed into it exhibits a thin compression peak of about 1 µm thick followed by a relatively long (∼1 mm) rarefaction area. A rough evaluation of frequency associated with such a wave gives the value of 10 6 Hz or higher, where f is frequency and α is a decay rate defined by an exponential law of attenuation of the value of U: 16] α/f for PS and PMMA is equal to 1.7 .…”

Shadowgraphic Imaging of Fibre-Delivered Pulsed IR Laser-Induced Heat Transfer across Thin Aluminized Polymer Film

“…Also, the instability of the cavity during the collapse phase is consistent with the onset of the Rayleigh-Taylor instability for a curved liquid-gas interface [30]. Once, the bubble reached to its maximum radius the velocity of the bubble wall and hence the liquid falls to zero and the potential energy E p of the cavity can be found from the work done on the water [18]:…”

“…Since, thin films can be in the form of a single, double and multilayer, thus the problem can be further complicated by number of layers and that each requires a careful analysis. For example, removal of superficial layer without damaging the underneath substrate or in the case of la- ser-induced shock waves in water using an interferometric method [18], UV laser ablation of thin metal films by fast photography [19], laser polymer ablation by shadowgraphy [20], the heat transfer in fluid by optical methods [21], IR thermography to study the heat transfer [22], LIFT in thin films using shadowgraphy [23], the laser-driven nanopowders using shadowgraphic technique [24] heat transfer in water using schlieren technique [25] and imaging the metal thin film ablation by dynamic TEM [26]. Based on the previous works and the apparently the lack of information in literature on imaging of both sides of a thin film during IR laser heating, the purpose of this research is to describe the results of laser-induced heat transfer through a double layer aluminized coated Polyethylene terephthalate (PET) thin film under water utilizing shadowgraphy technique.…”

On nonlinear wave dissipation in polymers

“…Using this approach we estimated the attenuation coefficient for the initial shock wave we apply in our experiments for soliton generation. As we have previously shown in [7] the shock wave produced in water by means of laser evaporation of a metallic target immersed into it exhibits a thin compression peak of about 1 µm thick followed by a relatively long (∼1 mm) rarefaction area. A rough evaluation of frequency associated with such a wave gives the value of 10 6 Hz or higher, where f is frequency and α is a decay rate defined by an exponential law of attenuation of the value of U:…”