Dynamics Of Laser-induced Bubble Research Articles

Laser induced cavitational luminescence in a bipolar acoustic pulse wave

Laser induced bubble dynamics (200–300 μs life time) under the influence of a convergent bipolar acoustic pulse (100 bar, 2 μs) in water is investigated experimentally. The amplitude of both an emitted shock and luminescence from the bubble collapse are recorded by a pvdf pressure probe and a photomultiplier tube (which integrates the spectral range from 260 to 530 nm). Different delay time (phase) between collapse and pressure pulse is found to influence the luminosity. For certain phases the average amplitude of the luminescence signal is increased by an order of magnitude in comparison with the average signal from an undisturbed collapse (i.e., outside the additional pressure pulse). Photorecordings show that bubbles re-expand after the first collapse nonspherically if an acoustic pulse was applied. They form a nose on the shadow side of the pulse wave which is possibly indication for jetting. Results for a collapse of a laser cavitation bubble and a bubble produced by shock cavitation are compared. [Work supported by DAAD and RFBR.]

Dynamics of Laser-Induced Bubble in Pressurized Liquid Nitrogen.

The dynamics of a laser-induced bubble in liquid nitrogen is studied experimentally. The motion of an almost spherical bubble, formed under appropriate control of optical conditions, is visualized by high-speed photography. Low subcooled liquid nitrogen at 78.0 K is used; the resulting high vapor pressure inside a bubble causes motion different from that in water at normal temperatures. Pressure is applied to liquid nitrogen to increase the degree of subcooling. An induced bubble grows similarly to a Rayleigh bubble under the effect of liquid inertia. The high vapor pressure, however, retards the collapse from the Rayleigh's solution, and makes the bubble surface rough by Taylor instability coupled with themodynamical effect. Estimation of the cavitation parameter in experiments of liquid nitrogen and water enables us to understand the transition from the motion being heat transfer dominant to that being liquid inertia dominant.

The Dynamics of Pulse-Laser-Induced Bubble in Liquid Nitrogen.

The behavior of bubbles in cryogenic liquids may differ from those in water or other normal temperature liquids, because the subcooled degree and their thermophysical properties are greatly different from normal ones. Experimental reports of laser-induced cryogenic bubbles, however, have been quite insufficient. This paper describes an investigation of the behavior of pulse-laser-induced vapor bubble in liquid nitrogen. The bubble is produced by pulsed irradiation of a ruby laser. The dynamics of laser-induced bubble is visualized by high-speed photography of an image-converter camera. The pressure signals from the bubble motion in the liquid nitrogen have been measured. For comparison with the experimental results, numerical study has also been performed on the dynamics of a single spherical bubble in liquid nitrogen with including the phase change effects.

Dynamics of Laser-Induced Bubble in Pressurized Liquid Nitrogen.

The dynamics of a laser-induced bubble in liquid nitrogen is studied experimentally. The motion of an almost spherical bubble, formed under appropriate control of optical conditions, is visualized by high-speed photography. Low subcooled liquid nitrogen at 78.0 K is used ; the resulting high vapor pressure inside a bubble causes motion different from that in water at normal temperatures. Pressure is applied to liquid nitrogen to increase the degree of subcooling. An induced bubble grows similarly to a Rayleigh bubble under the effect of liquid inertia. The high vapor pressure, however, retards the collapse from the Rayleigh solution, and makes the bubble surface rough by Taylor instability coupled with themodynamical effect. Estimation of the cavitation parameter in experiments of liquid nitrogen and water enables us to understand the transition from the motion being heat transfer dominant to that being liquid inertia dominant.

Dynamics of laser-induced bubble and free-surface oscillations in an absorbing liquid

A series of laser-driven dynamic photocapillary effects in absorbing liquid are described. We have observed self-oscillations of the free surface of a liquid (iodine solution in ethanol) and laser-induced bubble trapping and oscillations excited by a low power cw argon laser.