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Title: Two-dimensional turbulence cross-correlation functions in the edge of NSTX

The 2D radial vs. poloidal cross-correlation functions of edge plasma turbulence were measured near the outer midplane using a gas puff imaging (GPI) diagnostic on NSTX. These correlation functions were evaluated at radii r = 0 cm, ±3 cm, and ±6 cm from the separatrix and poloidal locations p = 0 cm and ±7.5 cm from the GPI poloidal center line for 20 different shots. The ellipticity ε and tilt angle φ of the positive cross-correlation regions and the minimum negative cross-correlation “cmin” and total negative over positive values “neg/pos” were evaluated for each of these cases. The average results over this dataset were ε = 2.2 ± 0.9, φ = 87° ± 34° (i.e., poloidally oriented), cmin =-0.30 ± 0.15, and neg/pos = 0.25 ± 0.24. Thus, there was a significant variation in these correlation results within this database, with dependences on the location within the image, the magnetic geometry, and the plasma parameters. In conclusion, possible causes for this variation are discussed, including the misalignment of the GPI view with the local B field line, the magnetic shear of field lines at the edge, the poloidal flow shear of the turbulence, blob-hole correlations, and the neutral density 'shadowing'more » effect in GPI.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [3]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Lodestar Research Corporation, Boulder, CO (United States)
Publication Date:
Grant/Contract Number:
AC02-09CH11466; FG02-02ER54678; AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 10; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Plasma turbulence; Isotopes; Plasma confinement; Tokamaks; Signal processing
OSTI Identifier:
1394963
Alternate Identifier(s):
OSTI ID: 1394861

Zweben, S. J., Stotler, D. P., Scotti, F., and Myra, J. R.. Two-dimensional turbulence cross-correlation functions in the edge of NSTX. United States: N. p., Web. doi:10.1063/1.5002695.
Zweben, S. J., Stotler, D. P., Scotti, F., & Myra, J. R.. Two-dimensional turbulence cross-correlation functions in the edge of NSTX. United States. doi:10.1063/1.5002695.
Zweben, S. J., Stotler, D. P., Scotti, F., and Myra, J. R.. 2017. "Two-dimensional turbulence cross-correlation functions in the edge of NSTX". United States. doi:10.1063/1.5002695. https://www.osti.gov/servlets/purl/1394963.
@article{osti_1394963,
title = {Two-dimensional turbulence cross-correlation functions in the edge of NSTX},
author = {Zweben, S. J. and Stotler, D. P. and Scotti, F. and Myra, J. R.},
abstractNote = {The 2D radial vs. poloidal cross-correlation functions of edge plasma turbulence were measured near the outer midplane using a gas puff imaging (GPI) diagnostic on NSTX. These correlation functions were evaluated at radii r = 0 cm, ±3 cm, and ±6 cm from the separatrix and poloidal locations p = 0 cm and ±7.5 cm from the GPI poloidal center line for 20 different shots. The ellipticity ε and tilt angle φ of the positive cross-correlation regions and the minimum negative cross-correlation “cmin” and total negative over positive values “neg/pos” were evaluated for each of these cases. The average results over this dataset were ε = 2.2 ± 0.9, φ = 87° ± 34° (i.e., poloidally oriented), cmin =-0.30 ± 0.15, and neg/pos = 0.25 ± 0.24. Thus, there was a significant variation in these correlation results within this database, with dependences on the location within the image, the magnetic geometry, and the plasma parameters. In conclusion, possible causes for this variation are discussed, including the misalignment of the GPI view with the local B field line, the magnetic shear of field lines at the edge, the poloidal flow shear of the turbulence, blob-hole correlations, and the neutral density 'shadowing' effect in GPI.},
doi = {10.1063/1.5002695},
journal = {Physics of Plasmas},
number = 10,
volume = 24,
place = {United States},
year = {2017},
month = {9}
}