U.S. Department of EnergyOffice of Scientific and Technical Information
Two-dimensional turbulence cross-correlation functions in the edge of NSTX
Abstract
The 2-D radial vs. poloidal cross-correlation functions of edge plasma turbulence were measured near the outer midplane using the 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 data set were ε=2.2±0.9, φ=87±34o (i.e. poloidally oriented), cmin= -0.30±0.15, and neg/pos=0.25±0.24. Thus there was significant variation in these correlation results within this database, with dependences on the location within the image, the magnetic geometry, and the plasma parameters. 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 in the edge, the poloidal flow shear of the turbulence, blob-hole correlations, and the neutral density ‘shadowing’ effect in GPI.
- Authors:
-
- OSTI
- Publication Date:
- DOE Contract Number:
- AC02-09CH11466
- Research Org.:
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
- Sponsoring Org.:
- U. S. Department of Energy
- Subject:
- Gas puff imaging; NSTX; Tokamak; Turbulence
- OSTI Identifier:
- 1562028
- DOI:
- https://doi.org/10.11578/1562028
Citation Formats
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., 2017.
Web. doi:10.11578/1562028.
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:https://doi.org/10.11578/1562028
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:https://doi.org/10.11578/1562028. https://www.osti.gov/servlets/purl/1562028. Pub date:Fri Sep 01 04:00:00 UTC 2017
@article{osti_1562028,
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 2-D radial vs. poloidal cross-correlation functions of edge plasma turbulence were measured near the outer midplane using the 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 data set were ε=2.2±0.9, φ=87±34o (i.e. poloidally oriented), cmin= -0.30±0.15, and neg/pos=0.25±0.24. Thus there was significant variation in these correlation results within this database, with dependences on the location within the image, the magnetic geometry, and the plasma parameters. 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 in the edge, the poloidal flow shear of the turbulence, blob-hole correlations, and the neutral density ‘shadowing’ effect in GPI.},
doi = {10.11578/1562028},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Sep 01 04:00:00 UTC 2017},
month = {Fri Sep 01 04:00:00 UTC 2017}
}