Mogens T. Levinsen

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When a container of fluid is oscillated vertically, capillary waves develop on the surface if the amplitude exceeds a critical value. Experimentally one finds that the motion of small particles on the surface of the fluid is close to Brownian. Here we study the relative motion of particle pairs. The experiment establishes that particle motion is strongly(More)
We present direct observations of period doubling in the flash to flash pulse heights in single-bubble sonoluminescence. States involved are stable, spherically symmetry broken. Observations are made using seven detectors distributed in the equatorial plane of the bubble. Contrary to earlier experiments by Holt et al. [Phys. Rev. Lett. 72, 1376 (1994)],(More)
Using a fiber-based four-channel correlation scheme to investigate spatial and temporal correlations, we show that observations of period-doubling phenomena in single bubble sonoluminescence are primarily a result of spontaneously breaking the spherical symmetry in the bubble collapse and, at most, may show up as secondary effects in the flash-to-flash(More)
The size of the light-emitting region is a key parameter toward understanding the light-emitting processes in a sonoluminescing bubble. Here we present measurements of interference effects from particles with a diameter of approximately 2 microm situated 6-10 microm from a sonoluminescing bubble. From the angular size of the pattern and from an estimated(More)
The turbulent motion of capillary surface waves is studied using laser-induced fluorescence. A blue laser is focused onto the surface of a solution of fluorescein in water contained in a vertically shaken vessel. The movement of the resulting green spot is followed by a position-sensitive detector. The scaling behavior and cross-over phenomenon for the(More)
New experimental results at the onset of turbulence in a gravity-driven pipe flow are presented, and a simple phenomenological model is introduced to describe the intermittent behavior observed. In this model slugs are stochastically produced at the pipe inlet, and the decrease in velocity due to turbulent friction is taken into account. The present(More)
2014 The first measurements on the Dayem bridge showed that the behaviour in an applied microwave field was quite different from that of the Josephson tunnel junction. Measurements on bridges one magnitude smaller later showed this difference to result from the bridge size. A very simple equivalent circuit was furthermore shown to characterize these small(More)
– We examine the applicability of the weak wave turbulence theory in explaining experimental scaling results obtained for the diffusion and relative diffusion of particles moving on turbulent surface waves. For capillary waves our theoretical results are shown to be in good agreement with experimental results, where a distinct crossover in diffusive(More)
In the early days of stable single-bubble sonoluminescence, it was strongly debated whether the emission was blackbody radiation or whether the bubble was transparent to its own radiation (volume emission). Presently, the volume emission picture is nearly universally accepted. We present new measurements of spectra with apparent color temperatures ranging(More)
On the surface of a vertically oscillated uid, capillary waves with a clearly discernible wavelength are formed if the amplitude of the oscillations exceeds a critical value. Particles sprinkled on the uid surface are experimentally found to move in an almost Brownian motion when measured over distances larger than. We extend earlier studies of the(More)