[ RadSafe ] Potential fusion reactor in collapsing bubbles

[John Jacobus]

>From PhysicsWeb at
http://physicsweb.org/articles/news/9/3/3

-----------------------------
Bubbles feel the heat
3 March 2005

Physicists have seen a region of plasma in a
single-bubble sonoluminescence experiment for the
first time. They have also found that the temperature
inside the bubble can reach up to 20,000 K (D
Flannigan and K Suslick 2005 Nature 434 52).


Collapsing bubbles 
In sonoluminescence, the bubbles in a liquid emit
light when they are forced to expand and collapse by
sound waves. Some physicists believe that the
pressures and temperatures inside the collapsing
bubbles could be high enough to initiate nuclear
reactions. However, the experimental evidence for
"sonofusion" remains controversial. 

In the latest experiments Kenneth Suslick and Daniel
Flannigan of the University of Illinois at
Urbana-Champaign find evidence for the formation of a
plasma in collapsing bubbles. According to Suslick and
Flannigan the formation of a plasma is a prerequisite
for a form of fusion known as inertial confinement
fusion to take place inside the bubble. 

The duo studied xenon- or argon-filled bubbles in
sulphuric acid, which has a low vapour pressure,
unlike the liquids studied in previous experiments.
This means that few if any vapour molecules - which
would otherwise absorb too much of the thermal energy
inside the bubble and therefore lower its temperature
- enter the bubbles. 

By analysing the light emitted from a single bubble,
Suslick and Flannigan were able to measure the
temperature at its surface. To their surprise, they
found temperatures could reach as high as 20,000 K.
According to Suslick, the emission comes from the
plasma formed by collisions of atoms and molecules
with high-energy particles inside the bubble. 

The scientists say that the temperature inside the
collapsing bubble must be even higher than at its
surface, but they did not detect any products from
fusion reactions. In 2002, and again last year, Rusi
Taleyarkhan and co-workers at Purdue University
claimed to have seen deuterium nuclei undergo fusion
reactions in bubbles in acetone. 

"Our results are in such a different set of
experimental parameters that they can neither confirm
or deny Taleyarkhan’s claims to fusion," Suslick told
PhysicsWeb. "A plasma is a prerequisite but certainly
not a sufficient condition for fusion." 

The Illinois scientists now plan to optimise
cavitation and explore the conditions generated during
bubble collapse. "Is inertial confinement fusion
possible in a collapsing bubble? I think the verdict
is still out," says Suslick. "The underlying physics
is solid - it is simply a question of whether the
collapse can generate a shockwave that is sufficiently
intense and remains spherical long enough."



=====
+++++++++++++++++++
"Baltimore is actually a very safe city if you are not involved in the drug trade."
DR. PETER BEILENSON, the city's health commissioner.

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com


	
		
__________________________________ 
Celebrate Yahoo!'s 10th Birthday! 
Yahoo! Netrospective: 100 Moments of the Web 
http://birthday.yahoo.com/netrospective/