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RESEARCH ACTIVITIES
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Director:
Prof. N.C. Luhmann,
Jr.
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Electron
cyclotron emission imaging (ECEI) is one of the many microwave diagnostics
that the DMRC develops and fabricates. Shown above are sample data from the
ECEI system on the DIII-D tokamak located at
General Atomics in San Diego, CA. ECEI is well-suited for diagnosing MHD
activity and interactions across multiple scales. The particular examples
above are images from a single DIII-D discharge comparing the fine-scale
structure of an Alfvén eigenmode
(left) to meso-scale perturbations due to a
core-localized kink instability (right). Covering a large region of the
plasma in 2D, ECEI enables reconstruction of helically symmetric structures
in the entire poloidal plane.
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ECE
imaging of the sawtooth crash at the inboard, or
high field side, shows that thermal transport occurs along a localized
conduction channel, consistent with a model for local magnetic
reconnection. The hot plasma is carried leftward, across the temperature
inversion radius, and ejected from the tokamak
core. The image is unambiguous, composed of localized measurements, and is
not subject to the uncertainties associated with the inversion of line
integrated measurements.
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ECEI
systems acquire data with micro-second resolution, allowing for accurate
discrimination among coupled and closely spaced eigenmodes.
In this case, the linear superposition of two separate Alfvén
eigenmodes (left 2 panels) produces a complicated
structure (right panel). But, the quality of ECEI data allows these modes
to be imaged separately for better understanding of their linear and
non-linear stability properties.
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NEWS
and PRESENTATIONS
v Professor
N.C. Luhmann, Jr. was awarded the 2012 John R.
Pierce Award for Excellence in Vacuum Electronics: "For outstanding
contributions and leadership in the field of vacuum electronics as a
scientist, engineer and educator"
v Dr. B.J. Tobias was awarded the Allen G. John Marr Prize
Distinguished Dissertation Award
v L. Yu, "Electronics Characterization and Data
Correction for Far Infrared Tangential Interferometry and Polarimetry (FIReTIP on
NSTX)," U.S. Transport Task Force Workshop, April 6-10, 2012.
v A. Baig, "Simulation
Analysis of Nano-CNC Fabricated 220 GHz Ultra Wide Band TWTA," 13th
International Vacuum Electronics Conference, April 24-26, 2012.
v R. Barchfeld, "Nano CNC
Milling of Two Different Designs of 0.22 THz TWT Circuits," 13th
International Vacuum Electronics Conference, April 24-26, 2012
v Dr. J. Zhao, "Scandate-Added
Tungsten Dispenser Cathode Fabrication for 220 GHz Sheet Beam Traveling
Wave Tube Amplifier,"13th International Vacuum Electronics Conference,
April 24-26, 2012.
v Dr. B.J. Tobias, (Invited Talk), "ECE-Imaging of
the H-Mode Pedestal," 19th Topical Conference High-Temperature Plasma
Diagnostics, May 6-10, 2012.
v Prof. N.C. Luhmann, Jr.,
"Electron Cyclotron Emission Imaging on KSTAR," 19th Topical
Conference High-Temperature Plasma Diagnostics, May 6-10, 2012.
v X. Ren, "Simulation of an
Expanded, Robust Operating Space for Density Fluctuation Measurements by 2D
Imaging Reflectometry," 19th Topical
Conference High-Temperature Plasma Diagnostics, May 6-10, 2012.
v Dr. C.W. Domier,
"Electron Cyclotron Emission Diagnostics for EAST," 19th Topical
Conference High-Temperature Plasma Diagnostics, May 6-10, 2012.
v Dr. B.J. Tobias, "Microwave Imaging Reflectometry from Concept to Construction: The Role of
Modeling and Laboratory Characterization in Diagnostic Development,"
39th International Conf. on Plasma Science, July 8-12, 2012.
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