by Grainger Professor Gerald
Kulcinski, Fusion Technology Institute researchers are among
those at UW-Madison whose research will benefit ITER. FTI researchers
are conducting ITER neutronics analyses, helping design and analyze
ITER tritium breeding blanket and shield modules, and modeling
Physicists persevere in quest for inexhaustible
fuel prices soar and greenhouse gases continue to blanket the atmosphere,
the need for a clean, safe and cheap source of energy has never seemed
more pressing. Scientists have long worked to meet that need, exploring
alternative energy technologies such as wind and solar power. But, after
decades of quiet progress, the spotlight is now on another potentially
inexhaustible energy source.
The largest fusion-energy
experiment ever conducted, ITER
(The International Thermonuclear Experimental Reactor) is the culmination
of years of research by scores of scientists, and is poised to answer
long-standing questions about the real-world viability of fusion energy.
An international collective
of physicists and engineers is working to both complement and lend expertise
directly to the ITER initiative and researchers at UW-Madison are firmly
placed among them. “[ITER] is a major threshold that we’ve
been waiting to get to for 20 years,” says Professor Ray
Fonck, the chief scientist of ITER’s U.S. project office.
“The project is the No. 1 priority in fusion research in the country
and the world, and essentially takes us to a regime we’ve never
been to before.”
Fusion energy describes the
energy released when atomic particles “fuse” together to
form heavier particles. The process is fundamental to our universe,
fueling both the sun and the stars. Here on Earth, physicists have tried
to harness the energy potential of nuclear fusion by working with plasma,
essentially a collection of particles, such as hydrogen nuclei, that
carry electric charge.
Because hydrogen can be easily
extracted from seawater—a cheap and abundant resource—scientists
have been tantalized by the prospect of plasma one day serving as an
But plasma has to be very,
very hot—on the order of millions of degrees—for its gas
particles to efficiently collide and release energy. “Basically,
we’re trying to make a sun here on Earth,” says Physics
Professor Stewart Prager, who also advises the U.S. government on national
fusion-energy research. “But it turns out to be one of the most
difficult scientific problems in the world.”
One of the biggest hurdles,
of course, is finding a container that can hold searing hot plasma without
burning down itself. Scientists have been working around the problem
by using invisible magnetic fields to hold the plasma in place, but
they are still searching for the most efficient and optimal ways to
UW-Madison scientists are
delving into pure physics and engineering research questions surrounding
the issue. Their work both complements ITER’s goals and, in a
sense, looks one step beyond it.
Prager and his team, for
instance, run the Madison
Symmetric Torus (MST), the largest fusion-energy experiment on campus.
Working with a device known as Pegasus, Fonck and his group are exploring
weaker magnetic fields, but are approaching the issue in a way different
from the MST.
Unlike the donut shape of
the MST, the plasma within Pegasus looks more like a ball with a small
hole in it, which influences how the plasma behaves. Fonck’s work
relies on the same fundamental physics that is at the heart of ITER’s
design, and could one day lead to new methods for testing large-scale
components in future fusion reactors.
Electrical & Computer
Engineering Professor David
Anderson recently made waves when he designed a new device that
holds plasma within a magnetic field, without an electric current in
the plasma to power the field.
“The current is running
in external wires and not in the plasma itself, and that represents
a tremendous engineering advantage,” says Anderson, who works
with a plasma instrument known as the Helically Symmetric eXperiment,
the only machine of its kind in the world. Plasma can become unstable
in the presence of a current, so Anderson is exploring ways to trick
the plasma into staying in place by twisting the surrounding magnetic
field into a special—and highly complicated—shape.
“It’s very exciting
to work on something that’s totally new and offers potential advantages
to the field,” says Anderson. “A lot of what we’re
all doing here in Wisconsin is looking for what the next research steps
will be beyond ITER. In that way, we really do have a unique place in
the world’s fusion-energy research program.”