Bubble Sonoluminescence Research Articles

The effects of buoyancy on sonoluminescing bubbles

Sonoluminescence from a single bubble was studied under microgravity and hypergravity environments to determine how buoyancy affects the light emission. The long-term objective of these experiments is to determine if buoyancy-related instabilities play a role in limiting the parameter space of single-bubble sonoluminescence. Understanding the parameter space limitations may ultimately lead to novel approaches for enhancing the extreme conditions within the bubble. Our results reveal several buoyancy-related effects, which should be further investigated in an extended microgravity environment.

Thermal noise and the stability of single sonoluminescing bubbles

The stability of a bubble levitated in an acoustic field under single bubble sonoluminescence conditions was numerically investigated taking thermal noise effects into consideration. Due to the microscopic size of a sonoluminescing bubble thermal noise is important to its surface and is found to cause small irregularities in its spherical shape. A stochastic differential equation in Langevin form is derived to describe the dynamics of a perturbation from the spherical and solved together with the Rayleigh-Plesset equation. The mechanisms responsible for the amplification of small irregularities are examined and a stability threshold is derived, which is in good agreement with experimental threshold data of Holt and Gaitan.

Mie scattering from a sonoluminescing bubble with high spatial and temporal resolution

The dynamics of a single-air bubble trapped in a resonant sound field in water has been characterized by Mie scattering and a Streak camera with high spatial and temporal resolution. The streak images show that in the endphase of the cavitation collapse the scattered light intensity is no function of the bubble radius anymore. In the last nanoseconds around minimum bubble radius most of the light is scattered at the highly compressed water surrounding the bubble and not at the bubble wall. This leads to a minimum in the scattered light intensity about 700 ps before the sonoluminescence pulse is emitted. And neglecting this changes leads to a strong overestimation of the bubble-wall velocity. In the reexpansion phase the high spatial resolution of the streak camera allows one to distinguish between the light scattered at the bubble wall and the light scattered at the outgoing shock wave.

Squeezing Alcohols into Sonoluminescing Bubbles: The Universal Role of Surfactants

We conduct an experimental study of the dependence of single bubble sonoluminescence intensity on the concentration of various alcohols. The light intensity is reduced by one-half at a molar fraction of ethanol of approximately 2.5x10(-5); butanol achieves the same reduction at a concentration 10 times smaller. We account for the results by a theoretical model in which the alcohols are assumed to be mechanically forced into the bubble at collapse, modifying the adiabatic exponent of the gas. The increasing hydrophobicities of the alcohols lead to decreasing effective adiabatic exponents, and thus to less heating and therefore less light. Support for this model is obtained by replotting the experimental light intensity values vs the calculated exponents, yielding a collapse of all data onto a universal curve.

Single-bubble sonoluminescence in microgravity

Single-bubble sonoluminescence refers to the emission of light from an acoustically trapped bubble undergoing highly nonlinear, presumably radial oscillations. The intensity of the emitted light depends strongly on the forcing pressure, and is limited by the development of instabilities that ultimately results in the extinction of the bubble. In this article, we discuss a possible contributing factor for the generation of instabilities; specifically, we examine the effect of the gravitational force on a sonoluminescence bubble.

Bremsstrahlung of nitrogen and noble gases in single-bubble sonoluminescence

A hydrodynamic model, discussing neutral gases as well as plasmas, is applied to simulate single-bubble sonoluminescence. In this model, thermal conduction and various inelastic impact processes such as dissociation, ionization, and recombination are considered. Bremsstrahlung is assumed as the mechanism of the picosecond light pulse in sonoluminescence. Diatomic nitrogen and noble gas bubbles are studied. The results show that the sonoluminescing bubbles are completely optically thin for bremsstrahlung. The calculated spectra agree with previous observations, and can explain the observed differences in spectra of different gases.

The radial motion of a sonoluminescence bubble driven with multiple harmonics

Harmonic excitation has been reported to enhance the light emission of a single sonoluminescing bubble by as much as 300% [J. Holzfuss, M. Rüggeberg, and R. Mettin, Phys. Rev. Lett. 81, 1961–1964 (1998)]. In this paper it is shown that the effect of harmonic excitation on the radial motion of the bubble is consistent with bubble dynamics predictions. Also, it has been suggested that the energetic collapse of a sonoluminescence bubble can be enhanced with the addition of an acoustic “spike” drive [W. C. Moss et al., Phys. Lett. A 211, 69–74 (1996)]. Preliminary attempts to spike the bubble with an acoustic pulse (positive and negative) resulted in a temporary increase in light intensity of ≈ 200%; however, a strong acoustic radiation force pushes the bubble away from the antinodal region, suggesting that “spiking” the bubble each and every acoustic cycle may not be feasible.

Stability control of single bubble sonoluminescence light

A micron-sized water bubble can be held fixed in a glass flask using an ultrasonic pressure field, and can be made to emit picosecond pulses of light that contains all colors. This phenomenon is called single bubble sonoluminescence (SBSL). The late Prof. Julian Schwinger had put forth a possible cause for SBSL, and postulated that the SBSL light consisted of photons that are emitted in pairs. Prior to testing for Schwinger's idea of photon pairs, we conducted experiments to measure the intensity fluctuations in SBSL using single-photon counting. By controlling the relative phase between the drive and feedback signals, through a PC computer, a light-emitting water bubble in an acoustically resonant flask could be maintained, while the fluctuations in the single-photon counts were limited to the square root of the number of detected photons. We demonstrate the possibility of maintaining a long-term stabilized sonoluminescence bubble, while simultaneously keeping the bubble light intensity at the level of single-photon sensitivity. Our results explicitly show that sonoluminescence light can be stabilized for experimental investigations that test for possible photon pairs from SBSL.

Time correlated single photon mie scattering from a sonoluminescing bubble

Application of time correlated single photon counting to pulsed Mie scattering enables one to resolve changes in light scattering to better than 50 ps. This technique is applied to the highly nonlinear motion of a sonoluminescing bubble. Physical processes, such as outgoing shock wave emission, that limit the interpretation of the data are measured with a streak camera and microscopy. Shock speeds about 6 km/s have been observed.

2809 DSMC 法による単一気泡の挙動の解析

In this study, a computational method, which consists of the Direct Simulation Monte Carlo method for the inside of the bubble and the well-known Keller's equation for the boundary of the bubble, is proposed for an analysis of a single spherical sonoluminescing bubble in water at molecular level. The present method includes the effect of evaporation and condensation of water molecules at the bubble wall which has never been considered in the previous method. Also air molecules inside the bubble are replaced with the mixture of uncondensable argon molecules and condensable water ones. The results show the improved characteristic histories of the bubble radius, temperature and number of molecules inside the bubble which agree qualitatively with the experimental ones.

Mixture segregation within sonoluminescence bubbles

This paper concerns a relaxation of the assumption of uniform mixture composition in the interior of sonoluminescence bubbles. Intense temperature and pressure gradients within the bubble drive relative mass diffusion which overwhelms diffusion driven by concentration gradients. This thermal and pressure diffusion results in a robust compositional inhomogeneity in the bubble which lasts several orders of magnitude longer than the temperature peak or light pulse at the main collapse of the bubble. This effect has important consequences for control of sonoluminescence, gas dynamics, sonochemistry, and the physics of light production.

All good oscillations must come to an end

The Rayleigh–Plesset equation (RPE) describes the growth, collapse, and subsequent rebounds of a sonoluminescing bubble, as long as unphysical values of the surface tension and viscosity are used. If realistic values of the surface tension and viscosity are used, the RPE produces insufficiently damped bubble dynamics, which disagree with experimental data. Every derivation of the RPE assumes that the compressibility of the liquid gives rise to the damping. We show that the compressibility of the liquid is at most a second-order effect. The damping comes from the most compressible component of the system, which is the gas, not the liquid. This simple physical reasoning generates a new RPE that reproduces the extreme damping that is observed experimentally, using tabulated values of surface tension and viscosity; a result that is unobtainable with all previous versions of the RPE. Our results affect the calculated limits of stability of sonoluminescing bubbles as well as the calculated magnitude of acoustic emissions from collapsing bubbles. a)This work was performed under the auspices of the U.S. Department of Energy under Contract No. W-7405-Eng-48. b)Supported by NSF.

Nature of the “Extreme Conditions” in Single Sonoluminescing Bubbles

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionNature of the “Extreme Conditions” in Single Sonoluminescing BubblesFrançoise Lepoint-Mullie, Damien De Pauw, Thierry Lepoint, Philippe Supiot, and Rudi AvniCite this: J. Phys. Chem. B 1999, 103, 16, 3287Publication Date (Web):April 7, 1999Publication History Published online7 April 1999Published inissue 1 April 1999https://doi.org/10.1021/jp9906740Copyright © 1999 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views175Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (20 KB) Get e-Alerts Get e-Alerts

Nature of the “Extreme Conditions” in Single Sonoluminescing Bubbles

A plasma diagnostics analysis is reported which looks at the experimental spectrum of the sonoluminescence emitted by a single argon bubble oscillating nonlinearly in an acoustic field. Under the hypothesis that the bubble is mainly filled with Ar atoms able to participate in the plasma, an order-of-magnitude estimation of the electron density (Ne) associated with the intracavity medium gives Ne ≈ 1025 m-3, with an electronic temperature estimated to be about 20 000 K, perhaps more. This analysis suggests that the conditions at the root of single-bubble sonoluminescence are highly energy charged and may be compatible with a sparklike process. The plasma developed inside the argon bubble is assumed to be in local thermodynamic equilibrium.

Computed optical emissions from a sonoluminescing bubble

A sonoluminescing bubble has been modeled as a thermally conducting, partially ionized plasma. The model is more complete than previous models, due to the inclusion of both plasma and normal molecular thermal conduction, vapor pressure, surface tension, the mixing of gas and water vapor in the bubble, and opacities. The model accounts for most of the observed experimental trends, including (i) the asymmetric pulse shape; (ii) the temperature and driving pressure dependence of the pulse width and intensity; and (iii) spectral shapes, in particular, the 300-nm peak in the spectrum of xenon sonoluminescence, which to our knowledge has not been explained by any previous model; and (iv) a hydrodynamic explanation of why water is the ``friendliest'' liquid in which sonoluminescence occurs. The agreement between the calculations and the data, as well as the model's predictions of almost every experimental trend, suggest strongly that the spectral and temporal properties of the emissions of a sonoluminescing bubble are due to adiabatic- or shock-initiated thermal emission from a cool dense plasma.

The real-gas effect in single-bubble sonoluminescence

The full set of hydrodynamic equations governing the oscillation of a bubble is solved numerically by using a modified equation of state with ionization. We show that the hydro-thermal process in the form of compression waves and low-level ionization are dominant inside a sonoluminescing bubble for a wide range of driving pressure. The resulting thermal bremsstrahlung radiation has pulse heights and widths that agree with experimental data for cases considered in this paper.

Inertial cavitation and single–bubble sonoluminescence

Sonoluminescence is investigated experimentally from the perspective of the dynamics of a single inertial cavitation bubble levitated in an acoustic sound field. The discussion includes bubble levitation, the inertial cavitation threshold, the parameter space in which stable singlendash;bubble sonoluminescence is observed, measurements of the acoustic and electromagnetic emissions from a sonoluminescence bubble, and the effects of impurities on the quality of the light emission from sonoluminescence bubbles. Comparisons are also made between sonoluminescence from a single bubble and sonoluminescence from a cavitation field.

Water vapor and sonoluminescence

In recent work, it has been shown that segregation of gas mixtures within sonoluminescence bubbles is driven by strong thermal and pressure gradients inside the bubble [B. D. Storey and A. J. Szeri, ‘‘Mixture segregation within sonoluminescence bubbles,’’ in review]. Although these rather exotic types of diffusive transport are often neglected, they are of crucial importance in a number of applications. These effects conspire to increase the fraction of the lighter gas in a mixture of noble gases near the center, and to increase the fraction of the heavier gas near the bubble wall at the moment of extreme collapse. This results in a greater energy concentration at the bubble center. While the temperature and pressure peaks have a duration (FWHM) of only a few hundred picoseconds at most, it has been found that appreciable mixture segregation persists for several orders of magnitude longer. Armed with this new understanding of how gas mixtures behave, it is possible to investigate more deeply the question of water vapor within the bubble. Several investigators have shown that the presence of water vapor has important consequences for compression versus shock heating, for hydrodynamics of the bubble collapse, and for chemistry.

Computed optical emissions from a star in a jar

A sonoluminescing bubble has been modeled as a thermally conducting, partially ionized plasma. The model accounts for most of the observed experimental trends, including (i) the asymmetric pulse shape; (ii) the temperature and driving pressure dependence of the pulse width and intensity; and (iii) spectral shapes, in particular, the 300-nm peak in the spectrum of xenon sonoluminescence. The agreement between the calculations and the data, as well as the models predictions of almost every experimental trend, leave little doubt that the spectral and temporal properties of the emissions of a single sonoluminescing bubble are due to adiabatic- or shock-initiated thermal emission from a cool dense plasma. [Work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.]

Experimental investigation of dynamics of sonoluminescing bubbles

Light scattering was carried out for a cavitation bubble trapped in a spherical flask. A He–Ne laser of 7 mW was used as the light source and the scattering angle was 90 deg. A function generator was used as the trigger source and a digital phospher oscilloscope for averaging the data. Changing the drive voltage resulted in differences in the signal waveform above and below the sonoluminescence threshold; a sonoluminescing bubble had the maximum radius greater than a dark bubble did, but showed smaller rebounds. This suggests that energy concentration is made possible by tight and symmetric collapse of the bubble. Sonoluminescence signals were also retrieved for a few hours with no laser light, and a discontinous drift was noted in the appearance time on the oscilloscope, suggesting that a bubble may have drifted in space discontinuously. [Work supported by Grant-in-Aid for Scientific Research, Ministry of Education, Science, and Culture, Japan.]