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spatial variations. Similarly, in the outer
gap scan, we see a large component of
the turbulence that is broad in kr at finite
kq as expected in core turbulence, while
there are also modes that are narrow in kr
and wide in kq, as well as modes at kq=0.
We will work with the newly developing
edge code models, such as BOUT and
CEPES, to identify these components and
determine which are important to edge
transport and which are incidental.
B. Plasma Surface Interactions (PSI)
Prof. Dennis Whyte leads this effort, in collaboration
with scientists at the University
of California, San Diego and the University
of Tennessee. For plasma confined by
magnetic fields in a laboratory setting, or
for inertially confined plasma in a vacuum
chamber, some of the charged particles
and/or energetic neutral atoms escape
and impact a surrounding solid material
surface. The first state of matter, solids, and
the fourth state of matter, plasma, therefore
meet in the study of Plasma-Surface Interactions
or PSI. Understanding and controlling PSI is
critically important to a large variety of plasma
applications: the fabrication of modern electronic
devices, the lifetime of plasma-based thrusters for
space exploration, and the surrounding material
surfaces in a fusion reactor (which is possibly the
harshest environment ever engineered for materials.)
Over the last few years the PSFC has started
developing a broad set of research tools to examine
PSI science. The science challenge of PSI lies in
the fact that it requires an understanding of many
coupled phenomena over an extremely large range
of spatial and time scales. In collaboration with UC
San Diego and the University of Tennessee, the
PFSC has founded a PSI Science Center sponsored
by the Department of Energy Office of Fusion Energy
Science. The Center brings to bear worldleading
experimental, modeling and measurement
tools focusing on the fundamentals of PSI science.
The cornerstone experimental facility at MIT is the
DIONISOS (Dynamics of IONic Implantation & Sputtering
On Surfaces) experiment. It has the unique
combination of providing continuous plasma bombardment
of surfaces while simultaneously probing
the surface properties with a high-energy ion
Members of the PSI group include group leader Dennis Whyte (standing right), and (left to right)
Peter Stahle ( standing) Regina Sullivan, Brandon Sorbom, Graham Wright, Harold Barnard and
Kevin Woller.
beam provided by a 1.7 million volt accelerator.
This allows DIONISOS to take real-time “snap-shots”
of how the material surface is responding to the
plasma and uncover its dynamic response.
Recent research has focused on the development
of complex surface nano-tendrils in refractory
metals when exposed to helium plasmas. This
effect could have a significant impact on using
tungsten in magnetic fusion reactors. It has been
shown that the tendrils have very constant high
helium concentration, about 1% of the tungsten,
indicating the likely importance of helium bubbles
in forming the tendrils. In addition, in collaboration
with Alcator C-Mod, it was shown for the first
time that the tendrils could be formed and could
survive in the divertor region of a tokamak, which
has possible important implications for ITER and
future fusion reactors.
C. International Collaboration on JET
This experimental program is led by Prof. Miklos
Porkolab, and Senior Research Engineer Dr. Paul
Woskov of the PSFC. Collaborative experiments
are being carried out among the PSFC (MIT), CRPP
(Lausanne, Switzerland) and UK scientists at the
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