Single Bubble Sonoluminescence.
Rachel Ruch, San Francisco State University,
Harold Metcalf and John Noé, Laser Teaching Center, SUNY at
Single bubble sonoluminescence (SBSL) is the process of creating
flashes of light using ultrasonic sound waves. It is a phenomenon of
considerable current interest due to the extremely high temperatures
reached (above 10,000 K) and the mysteries still shrouding the details
of the mechanism.
SBSL is brought about by injecting a gas bubble into a flask of
liquid, typically degassed water, that is vibrating at its fundamental
resonance of $\sim$26 kHz. Two piezoelectric transducers (PZTs) on
opposite sides of the flask create the necessary intense standing
wave. The bubble is attracted to the vibrational node at the center
of the flask, where it repeatedly expands and contracts due to the
changing sound pressure in the surrounding liquid. The rapid collapse
of the bubble causes it to emit photons which appear to peak in the
Achieving SBSL requires $\sim$1000 peak volts AC across the PZTs.
This high voltage can be attained with the use of a series LRC tuned
circuit in which the PZT acts as an electrical capacitor. Most of our
efforts in this project were concentrated on constructing and tuning
this circuit and developing a suitable amplifier to drive it. While we
were also able to repeatedly capture bubbles in the intense sound
field, we did not attempt to observe the SBSL light in the limited
time available for this.
This study was supported by NSF Grant No. PHY99-12312.