Radially resolved measurements of plasma rotation and flow-velocity shear in the Maryland Centrifugal Experiment

Journal Article · Wed Feb 15 00:00:00 EST 2006 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2167915· OSTI ID:20782508

Ghosh, J; Elton, R C; Griem, H R; Case, A; Silva, A.W. de; Ellis, R F; Hassam, A; Lunsford, R; Teodorescu, C ^[1]

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1. University of Maryland, College Park, Maryland 20742 (United States)

In diagnosing the Maryland Centrifugal Experiment (MCX) [R. F. Ellis et al., Phys. of Plasmas 8, 2057 (2001)], earlier spectroscopic measurements of averaged plasma rotation velocities have been upgraded to include radial distributions, using a five-channel fiber-optic collection system. Detailed information from each view is now possible with an 8-times increase in spectral resolution, by using a 2 m spectrograph and a 2400 lines/mm grating. Inversion of the integrated chordal radiation into a radial dependence of local emissions is performed by two methods: (a) an iterative simulation beginning with assumed emissions in five axially concentric cylindrical zones followed by summation along the five viewing chords, and (b) inversion of a combination of dual Abel-type matrices. The radial profiles of the absolute velocities derived cover a range from 20 to 70 km/s for both C{sup +} and C{sup ++} impurity ions. Previous apparent differences in velocities between ions from a single chordal observation are now explained by the measured radial dependence of velocities and relative emissions. An important result is the first direct and quantitative measurement on MCX of a radial shear in rotational flow velocity as large as 9x10{sup 5} s{sup -1}, 9 times a threshold of 1x10{sup 5} s{sup -1} for magnetohydrodynamic stability. Stark-broadened hydrogen Balmer-series spectral lines provide both a value for electron density of N{sub e}=(8.5{+-}1.5)10{sup 14} cm{sup -3} and supporting data for radial particle distributions.

• OSTI ID: 20782508
• Journal Information: Physics of Plasmas, Vol. 13, Issue 2; Other Information: DOI: 10.1063/1.2167915; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CARBON IONS
COMPUTERIZED SIMULATION
CYLINDRICAL CONFIGURATION
ELECTRON DENSITY
EMISSION
FIBERS
HYDROGEN
ITERATIVE METHODS
MAGNETOHYDRODYNAMICS
MATRICES
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA IMPURITIES
PLASMA INSTABILITY
PLASMA SIMULATION
RESOLUTION
ROTATION
SHEAR
SPATIAL DISTRIBUTION
STABILITY
VELOCITY