Davis Millimeter-Wave Research Center

Microwave/Millimeter Wave Technology

Plasma Diagnostics

 

 

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Plasma diagnostics

 

µ-wave vacuum electronics

 

µ-wave solid state technology

 

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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.

 

 

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.

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.

 

 

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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