FY2010 - Oak Ridge National Laboratory

Director’s R&D Fund—
Advanced Energy Systems
05531
Plasma Heating to Enable Fusion Energy Plasma Material
Interface Research
John B. Caughman, Tim Bigelow, Steffi Diem, Richard H. Goulding, Donald L. Hillis, Martin Peng,
Dave Rasmussen, and John B. Wilgen
Project Description
A recent report to the Fusion Energy Sciences Advisory Committee (FESAC) stated that issues related to
plasma facing components and materials will require a major extrapolation from current state of
knowledge and will need substantial development. The R&D program needed to address these issues will
require new facilities to improve our understanding of the mechanisms underlying plasma-surface
interactions and the design of plasma facing components and radio frequency (RF) antennas. We
anticipate that ORNL will propose a new facility for addressing these critical issues. The facility will
require a large-area plasma (~100 cm 2 ) with reactor relevant heat flux (20 MW/m 2 ) and particle flux
(10 23 /m 2 s). We plan to use a helicon plasma source to create the plasma. However, substantial additional
plasma heating will be required to obtain the desired fluxes.
This project addresses the need to heat and control the plasma electrons using microwave power. The
high plasma density needed to obtain the desired plasma parameters for material and antenna testing
requires the use of either electron Bernstein waves or whistler waves. Such an approach needs to be
demonstrated with high magnetic fields (~1 tesla) in a cylindrical magnetic mirror geometry. We propose
to create and heat a high-density plasma to identify critical issues. We will use diagnostics and modeling
to measure and verify plasma performance to determine electron temperature/density power scaling,
wave-coupling mechanisms, needed magnetic field shape, and optimized launcher configurations.
Mission Relevance
The DOE Office of Fusion Energy Sciences recently conducted a series of Research Needs Workshops to
determine the key research opportunities, called the research thrusts, of the fusion energy program for the
next 20 years to address the gaps and issues in demonstrating fusion energy as a power source. The
plasma material interface—covering plasma surface interactions, plasma facing components, and RF
antennas—is identified as a critical area of research. It is expected that high priority will be assigned to a
new facility for studying the plasma-material interface at a high plasma flux, and also to a new facility for
studying RF antenna physics. Both of these facilities will require a high-density plasma over a large area.
The success of this project will position ORNL to take the lead in these research efforts and host the
required facilities. The likely funding range for these facilities is $50 million to $100 million each.
Results and Accomplishments
The primary objectives of the first year were to complete the experimental device, start the theoretical
work of modeling wave-plasma interactions, develop a launcher for whistler wave production, develop
diagnostics for plasma characterization, and begin plasma production. Substantial progress has been made
in each of these areas.
The experimental device consists of a central vacuum chamber surrounded by two magnet pairs on either
side. The vacuum chamber has a number of flanges for diagnostic and wave-launching access. The
chamber was pumped down and leak checked, the magnets were tested to 1000 amps, and initial plasma
operation was demonstrated in August.
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