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Meridian Speeches

Star in a Jar?

Presented by: Lawrence Crum (University of Washington)
Category: Special Interest   Duration: 1 hour and 30 minutes   Broadcast date: March 29, 2007
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When a sound wave of moderate intensity is propagated through water, light emissions can be observed. This conversion of sound energy into light energy is called Sonoluminescence (SL) and represents an energy amplification per molecule of over eleven orders of magnitude. The discovery in our laboratory that a single, stable gas bubble, acoustically levitated in a liquid, can emit optical emissions each cycle for an unlimited period of time stimulated considerable interest in this topic. Presumably, the oscillations of the bubble cause the gas in the interior to be heated to incandescent temperatures during the compression portion of the cycle. Because the lifetime of the optical pulse can be on the order of 50 picoseconds (million millonths of a second), it is likely that some rather unusual physics is occurring. One explanation for the short pulse length is that a shock wave is created in the gas which is then elevated to high temperatures by inertial confinement. If shock waves are the mechanism for SL emission, then optimization of the process has been speculated to lead to extraordinary physics, including thermonuclear fusion. Recent reports from a group at Oak Ridge National Laboratory (Science, vol. 295, 1868-1873, 2002) have even provided evidence for the nuclear emissions that should be associated with this phenomenon. Since this mechanism (thermonuclear fusion) is the energy source that drives our sun, one can even speculate that a miniature "star in a jar" has been created. A broad overview of this intriguing phenomenon will be presented as well a critical review of the potential for sonofusion.

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Lawrence Crum's presentation PowerPoint (.ppt)