from Purdue University have
found mechanisms that are vital to interactions between
surfaces inside a thermonuclear fusion reactor and hot plasma, which
could lead to the development of coatings capable of tolerating
radiation damage and ultimately, fusion power plants.
inner lining of a fusion reactor often faces horrific conditions
leading to radiation damage due to the hot plasma. With the use of
nanotechnology, nuclear engineers are looking to "define"
small features in the coating as a way to understand and develop a
new material that can come in contact with plasma and not be harmed.
Finding a material durable enough to withstand such
harsh conditions has been difficult, until now.
with researchers at Princeton
University in the Princeton Plasma Physics Laboratory,
Purdue researchers are using the National Spherical Torus Experiment
to test materials, which is the country's only spherical tokamak
reactor. They will also study materials in a special
"plasma-materials interface probe," then transfer these
materials to an "in situ surface analysis facility laboratory."
will bring the samples in and study them right there, and will be
able to do the characterization in real time to see what happens to
the surfaces," said Jean Paul Allain, an assistant professor of
nuclear engineering at Purdue University. "We're also going to
use computational modeling to connect the fundamental physics learned
in our experiments and what we observe inside the tokamak."
of the tested linings is lithiated graphite, which consists of
lithium being added to the inner graphite wall, and when it diffuses
into the reactor wall. Then deuterium atoms and the lithiated
graphite bind together in the fuel inside these tokamaks, which are
what the fusion reactors are called. A magnetic field inside the
tokamaks encloses a circular-shaped plasma of
deuterium, which is an isotope of hydrogen.
a fusion reaction occurs, deuterium atoms hit the inner lining of the
fusion reactor and can be sent back to the core and recycled back to
the plasma, or they're "pumped," which causes them to bind
with the lithiated graphite.
now have an understanding of how the lithiated graphite controls the
recycling of hydrogen," said Allain. "This is the first
time anyone has looked systematically at the chemistry and physics of
pumping by the lithiated graphite. We are learning, at
the atomic level, exactly how it is pumped and what dictates the
binding of deuterium in this lithiated graphite. So we now have
improved insight on how to recondition the surfaces of the tokamak."
use of a fusion power plant could cut exhaust completely because the
deuterium fuel is in seawater. Also, it could produce 10 times more
energy than a nuclear
fission reactor. Plants like these would be an endless
supply of clean energy.
study was led by Chase Taylor, a doctoral student, Bryan Heim, a
graduate student, and Allain. Two papers have been written on the
topic, and one will be presented at the Fusion Nuclear Science and
Technology/Plasma Facing Components meeting in August.