Proposal
Sonoluminescence (SL)
Cordelia Ochis
Sonoluminescence (SL) was first observed
in the early 1900ís. It did not become widely
known until Seth Putterman of Cal. Tech. began studying
it in 1989 [1]. Since then it has come to the forefront,
with more and more labs endeavoring to answer different
questions [1,3,4,5]. In SL an acoustically levitated
bubble grows and collapses in a repeating cycle. There
are many seeming mysteries attracting scientists to
the study of SL, such as the relative energies of sound
and light -sound is 12 orders of magnitude weaker than
light, which it produces here- and what could be contributing
to make up for this difference. The temperature of this
bubble can reach higher than 15,000 K [5], for comparison
the surface temperature of the sun is about 5,500 K.
This bubble has been found to be a thermally conducting,
partially ionized plasma [2]. At each collapse a burst
of light is emitted, the growth and collapse time is
so short that the light appears constant. Current theories
find that the ~100ps width of this burst is due to electron
conduction and the fluctuating opacity of the plasma
[3].
The Advanced Physics Laboratory (course 331) is strongly
recommended for all physics majors planning to do research
during the summer or to pursue science after graduation.
Taking 331 this semester is what led me to the idea
of adding a sonoluminescence experiment to the course.
Most experiments worked with during the course are already
fundamentally understood by physicists. It is still
beneficial for undergraduates to do these experiments,
but an experiment in a current hot area of research
has advantages also. During the course each student
writes two publication style papers on two of the experiments
they do. It is necessary to do outside reading and research
for these papers. A SL paper has the advantage of teaching
the student how to write a paper that may have as many
questions as answers. In the SL experiment students
could follow the lab book, or research current questions
about SL and design their own experiment to explore
one.
Over the course of the 10 weeks this summer I will design
and build the apparatus, stabilize the set up and experiment,
and write the laboratory guide. I will begin by researching
how different laboratories have built their apparatus
and what the advantages and disadvantages of each method
are. In order to design my apparatus I will have to
decide what the goals for the 331 physics lab are in
comparison to those of an active research lab. I will
build the apparatus itself, and then make adjustments
to it to achieve the desired results. I will develop
a reproducible experiment, and write it in detail for
future 331 lab students. I will have guidance from Mike
Noel and Thomas Carroll during each phase.
The apparatus for the experiment can
be surprisingly simple. A function generator is used
as a source of power and to control the frequency. An
audio power amplifier is used to create the correct
sonic pressure. A Piezo-Electric Transducer (PZT) creates
an ultra-sonic horn (USH) when attached to a metal rod
[6]. The bubble will be created inside a spherical glass
flask, filled with a water and glycerin solution. Much
of the equipment for the apparatus is already available
in the physics department. A high estimate of the cost
is $500 for anything we do not already have.
References:
1. G. Brumfiel, Nature, Vol 437, 27 October 2005
2. W.C. Moss, Physical Review E, Vol 59 Issue 3, March
1999
3. W.C. Moss, Science, Vol 276, 30 May 1997
4. D.J. Flannigan, K.S. Suslick, Nature, Vol 434, 3
March 2005
5. D. Lohse, Nature, Vol 434, 3 March 2005
6. C.J. Visker, Hamline University, St. Paul Minnesota,
Physics Honors Project, 2005
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