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Sonoluminescence as an Ultra-Dense Microplasma

Seminar: Departmental: Solid State Technology and Devices | November 30 | 1-2 p.m. | 521 Cory Hall

Dr. Brian Kappus, EECS/UCLA

Electrical Engineering and Computer Sciences (EECS), EE 298-12

Sonoluminescence is a quintessential energy focusing phenomenon. The
nonlinear interaction of a standing sound wave with a bubble leads to
pulsations that are so enormous that light is emitted at the moment of
maximum compression. A Xenon bubble is compressed to near-liquid densities
(1021/cc) and a temperature of 10,000K. Under these conditions a simple
application of equilibrium statistical mechanics predicts very low levels
of ionization and a photon mean free path four orders of magnitude larger
than the plasma (50 microns). Instead, recent findings show opaque
behavior. Light emission is a near perfect Planck black body and direct
pulsed laser probes show confinement to tens of microns. We conclude that
this previously overlooked region of parameter space contains a first-order
screening phase transition to a highly-ionized, dense plasma.

This novel microplasma could provide an ideal medium for absorbing
broadband electromagnetic radiation. Its short turn-on time suggest using
sonoluminescence as a ps switch. In addition, with plasma frequencies just
below optical, it could provide a non-linear medium for upshifting W band
to the THz domain. I will discuss our current efforts to extract
sonoluminescence from its fluid medium and into a controlled high-pressure
cell and explore possible applications., 510-642-2911