Diagnostic performance of the beam emission spectroscopy system on the National Spherical Torus Experiment

Journal Article · Mon Oct 15 00:00:00 EDT 2012 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4728094· OSTI ID:22093816

Smith, D. R.; Fonck, R. J.; McKee, G. R.; Thompson, D. S. ^[1]

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1. Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

The beam emission spectroscopy system on the National Spherical Torus Experiment measures localized density fluctuations on the ion gyroscale. Optical sightlines provide core to edge radial coverage, and the sightlines are aligned to typical pitch angles to maximize cross-field spatial resolution. Sightline images are 2-3 cm, and point spread function calculations indicate image distortion from pitch angle misalignment and atomic state finite lifetimes is minor with a 15% increase in the image size. New generation photodetectors achieve photon noise limited measurements at frequencies up to 400 kHz with refrigerant cooling at -20 Degree-Sign C. Measurements near the pedestal show broadband turbulence up to 100 kHz, and poloidal correlation lengths are about 10 cm. Plasma turbulence signals can be 2-3 orders of magnitude above photon noise and amplifier thermal noise.

• OSTI ID: 22093816
• Journal Information: Review of Scientific Instruments, Vol. 83, Issue 10; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
AMPLIFIERS
COOLING
CORRELATIONS
DENSITY
EMISSION SPECTROSCOPY
FLUCTUATIONS
INCLINATION
LIFETIME
NOISE
PERFORMANCE
PHOTODETECTORS
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
REFRIGERANTS
SPATIAL RESOLUTION
SPHERICAL CONFIGURATION
TOKAMAK DEVICES
TURBULENCE