Lab Experiments Mimic a Star's Energy Bursts (Forwarded)

From: Andrew Yee (ayee_at_nova.astro.utoronto.ca)
Date: 01/26/05 

Date: Wed, 26 Jan 2005 14:12:39 -0500

National Institute of Standards and Technology
Gaithersburg, Maryland

Media Contact:
Laura Ost, laura.ost@nist.gov, (301) 975-4034

January 26, 2005

Lab Experiments Mimic a Star's Energy Bursts

A key process that enhances the production of nuclear energy in the interior of
dense stars has been re-created in the laboratory for the first time by
physicists at the National Institute of Standards and Technology (NIST). The
work may help scientists study topics such as nuclear fusion as a possible
energy source and demonstrates a new method for studying and modeling dense
stellar objects such as white dwarfs.

The NIST experiments, described in the Jan. 18 issue of Physical Review
Letters,* involve temperature measurements of ultracold crystals as they melt.
First, a "plasma" of tens of thousands of singly charged beryllium atoms is
trapped using electric and magnetic fields and then cooled to almost absolute
zero using lasers. When the lasers are turned off, the plasma begins to heat up.
At 10 milliKelvin -- just 0.01 degree above absolute zero -- the temperature
suddenly rises more than 10 billion times faster than predicted by theory. This
burst of energy in a very cold system of highly interactive particles is
believed to mimic events occurring inside the hot, dense interiors of stars,
where plasmas of highly charged atoms undergo accelerated nuclear reactions.

Beryllium ions are frequently used in NIST research on topics such as
development of future atomic clocks and quantum computing studies. Such rapid
heating was first noticed in experiments attempting to prepare special states of
beryllium ions that can improve the precision of an atomic clock.

Scientists have suspected for decades that the fusion of atoms that powers stars
is enhanced when the plasmas at their cores somehow reduce the natural repulsion
between charged ions, increasing the chances that pairs of ions will collide and
produce nuclear reactions. NIST researchers found that, at a certain
temperature, their trapped beryllium ions also collided more frequently and that
the plasma temperature suddenly shot up. In this case, the collisions resulted
in a transfer of energy between two types of motions made by the ions.

The research was supported in part by the Office of Naval Research and National
Science Foundation.

* M.J. Jensen, T. Hasegawa, J.J. Bollinger, and D.H.E Dubin. 2004. Rapid heating
of a strongly coupled plasma near the solid-liquid phase transition. Physical
Review Letters, Jan. 18.

IMAGE CAPTION:
[http://www.nist.gov/public_affairs/techbeat/05PHY001_coldplasmas_HR.jpg (503KB)]
This false color image shows an ultracold plasma of 26,000 beryllium ions
fluorescing when hit by a laser pulse.

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