نتایج جستجو برای: sonoluminescence
تعداد نتایج: 336 فیلتر نتایج به سال:
A sonoluminescing bubble has been modeled as a thermally conducting, partially ionized, two-component plasma. The model shows that the measured picosecond pulse widths are due to electron conduction and the rapidly changing opacity of the plasma and that these mechanisms are also responsible for the absence of an “afterglow” subsequent to the sonoluminescence flash while the hot bubble expands ...
In this study, the Er:YAlO3 as up-conversion luminescence agent, which can transfer the visible light part in the sonoluminescence to ultraviolet light, was synthesized by nitrate–citrate acid and sol–gel method. And then the Er:YAlO3/TiO2–Fe2O3 composite as a sonocatalyst was prepared by ultrasonic dispersion and liquids boil method. The prepared Er:YAlO3/TiO2–Fe2O3 composite was characterized...
Zero-point fluctuations in quantum fields give rise to observable forces between material bodies, the so-called Casimir forces. In these lectures I present the theory of the Casimir effect, primarily formulated in terms of Green’s functions. There is an intimate relation between the Casimir effect and van der Waals forces. Applications to conductors and dielectric bodies of various shapes will ...
The mutual interaction between small oscillating cavitation bubbles (R0,10 mm) in a strong acoustic field ~Pa.1 bar, f 520 kHz! is investigated numerically. We assume spherical symmetry and a coupling of the bubble oscillations. Our results show that the strength and even the directions of the resulting secondary Bjerknes forces differ considerably from predictions of the well-known linear theo...
We investigate several means of coupling between a sonoluminescing bubble and an applied magnetic field. Recent experiments show a strong quadratic dependence between the forcing pressures required for stable sonoluminescence and magnetic field amplitude. However, all coupling mechanisms calculated here for comparable magnetic fields involve energies no more than one percent the mechanical ener...
The spectral shape and observed sonoluminescence emission from Xe bubbles in concentrated sulfuric acid is consistent only with blackbody emission from a spherical surface that fills the bubble. The interior of the observed 7000 K blackbody must be at least 4 times hotter than the emitting surface in order that the equilibrium light-matter interaction length be smaller than the radius. Bright e...
The dynamics of cavitation bubbles on water is investigated for bubbles produced optically and acoustically. Single bubble dynamics is studied with laser produced bubbles and high speed photography with framing rates up to 20.8 million frames per second. Examples for jet formation and shock wave emission are given. Acoustic cavitation is produced in water in the interior of piezoelectric cylind...
In a certain parameter region, a single sonoluminescencing bubble is unstable against diffusion of gases and their chemical dissociation. Experiments show that a surface unstable bubble emits a microbubble and recoils. After this it exhibits specific dynamical features whereby the ambient radius changes in a nonmonotonic way. A numerical analysis identifies the phenomenon as the result of the i...
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