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Title: Status and characterization of the lithium beam diagnostic on DIII-D

The 30 keV lithium beam diagnostic on DIII-D is suitable to measure both the radial electron density and poloidal magnetic field profiles in the pedestal. The refurbished system features a new setup to measure the Doppler shift allowing accurate alignment of the spectral filters. The injector has been optimized to generate a stable lithium neutral beam with a current of I= 15−20 mA and a diameter of 1.9 ± 0.1 cm measured by beam imaging. The typical temporal resolution is Δt= 1−10 ms and the radial resolution of ΔR= 5 mm is given by the optical setup. A new analysis technique based on fast Fourier transform avoids systematic error contributions from the digital lock-in analysis and accounts intrinsically for background light correction. Latest upgrades and a detailed characterization of the system are presented. Proof-of-principle measurements of the poloidal magnetic field with a statistical error of typically 2% show a fair agreement with the predictions modeled with the Grad-Shafranov equilibrium solver EFIT within 4%.
Authors:
;  [1] ; ; ;  [2] ;  [3] ;  [4]
  1. Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831-0117 (United States)
  2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
  3. Palomar College, 1140 West Mission Rd, San Marcos, California 92069-1487 (United States)
  4. University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States)
Publication Date:
OSTI Identifier:
22224165
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 84; Journal Issue: 8; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 43 PARTICLE ACCELERATORS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALIGNMENT; DOPPLER EFFECT; DOUBLET-3 DEVICE; ELECTRON DENSITY; ERRORS; FOURIER TRANSFORMATION; LITHIUM; MAGNETIC FIELDS; OPTICAL FILTERS; PARTICLE BEAMS; RESOLUTION