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Title: Disconnection of scrape off layer turbulence between the outer midplane and divertor target plate in NSTX

Abstract

The connection between scrape off layer (SOL) turbulence at the outer midplane and at the divertor target plate is characterized in the National Spherical Torus Experiment (NSTX). In this work, divertor fluctuations due to midplane blobs are studied by imaging their helical intersection with the divertor plate. Divertor fluctuation levels gradually decrease approaching the outer strike point. Divertor radial turbulence scale lengths as well as radial and poloidal turbulence propagation velocities are comparable to those on the low field side midplane. Strong correlation between divertor and midplane turbulence is observed in the far SOL. The correlation progressively decreases towards the separatrix, along with the decrease in the measured divertor fluctuations. The reduction in correlation is consistent with an electrostatic two-region blob model with perpendicular ion polarization currents due to X-point geometry causing filament disconnection.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3];  [4]; ORCiD logo [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Lodestar Research Corporation, Boulder, CO (United States)
  4. X Science LLC, Plainsboro, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1643699
Alternate Identifier(s):
OSTI ID: 1642353
Report Number(s):
LLNL-JRNL-774768
Journal ID: ISSN 0029-5515
Grant/Contract Number:  
AC02-09CH11466; AC52-07NA27344; FG02-97ER54392
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 2; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Scotti, F., Zweben, S., Myra, J., Maqueda, R., and Soukhanovskii, V. Disconnection of scrape off layer turbulence between the outer midplane and divertor target plate in NSTX. United States: N. p., 2019. Web. https://doi.org/10.1088/1741-4326/ab5886.
Scotti, F., Zweben, S., Myra, J., Maqueda, R., & Soukhanovskii, V. Disconnection of scrape off layer turbulence between the outer midplane and divertor target plate in NSTX. United States. https://doi.org/10.1088/1741-4326/ab5886
Scotti, F., Zweben, S., Myra, J., Maqueda, R., and Soukhanovskii, V. Wed . "Disconnection of scrape off layer turbulence between the outer midplane and divertor target plate in NSTX". United States. https://doi.org/10.1088/1741-4326/ab5886. https://www.osti.gov/servlets/purl/1643699.
@article{osti_1643699,
title = {Disconnection of scrape off layer turbulence between the outer midplane and divertor target plate in NSTX},
author = {Scotti, F. and Zweben, S. and Myra, J. and Maqueda, R. and Soukhanovskii, V.},
abstractNote = {The connection between scrape off layer (SOL) turbulence at the outer midplane and at the divertor target plate is characterized in the National Spherical Torus Experiment (NSTX). In this work, divertor fluctuations due to midplane blobs are studied by imaging their helical intersection with the divertor plate. Divertor fluctuation levels gradually decrease approaching the outer strike point. Divertor radial turbulence scale lengths as well as radial and poloidal turbulence propagation velocities are comparable to those on the low field side midplane. Strong correlation between divertor and midplane turbulence is observed in the far SOL. The correlation progressively decreases towards the separatrix, along with the decrease in the measured divertor fluctuations. The reduction in correlation is consistent with an electrostatic two-region blob model with perpendicular ion polarization currents due to X-point geometry causing filament disconnection.},
doi = {10.1088/1741-4326/ab5886},
journal = {Nuclear Fusion},
number = 2,
volume = 60,
place = {United States},
year = {2019},
month = {12}
}

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