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Title: Theory based scaling of edge turbulence and implications for the scrape-off layer width

Abstract

Turbulence and plasma parameter data from the National Spherical Torus Experiment NSTX [M. Ono, S.M. Kaye, Y.-K.M. Peng, G. Barnes et al., Nucl. Fusion 40, 557 (2000)] is examined and interpreted based on various theoretical estimates. In particular, quantities of interest for assessing the role of turbulent transport on the midplane scrape-off layer heat flux width are assessed. Because most turbulence quantities exhibit large scatter and little scaling within a given operation mode, this paper focuses on length and time scales and dimensionless parameters between operational modes including Ohmic, low (L), and high (H) modes using a large NSTX edge turbulence database [S.J. Zweben, W.M. Davis, S.M. Kaye, J.R. Myra et al., Nucl. Fusion 55, 093035 (2015)]. These are compared with theoretical estimates for drift and interchange rates, profile modification saturation levels, a resistive ballooning condition, and dimensionless parameters characterizing L and high H mode conditions. It is argued that the underlying instability physics governing edge turbulence in different operational modes is in fact similar, and is consistent with curvature-driven drift ballooning. Saturation physics, however, is dependent on the operational mode. Five dimensionless parameters for drift-interchange turbulence are obtained and employed to assess the important of turbulence in setting themore » scrape-off layer heat flux width lambda_q and its scaling. An explicit proportionality of the width lambda_q to safety factor and major radius (qR) is obtained under these conditions. Quantitative estimates and reduced model numerical simulations suggest that the turbulence mechanism is not negligible in determining lambda_q in NSTX, at least for high plasma current discharges.« less

Authors:
; ; ORCiD logo
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
DOE Contract Number:  
AC02-09CH11466
Product Type:
Dataset
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Edge turbulence Transport Scrape-off layer Heat flux
Keywords:
Edge turbulence Transport Scrape-off layer Heat flux
OSTI Identifier:
1366750
DOI:
10.11578/1366750

Citation Formats

Myra, J.R., Russell, D.A., and Zweben, S.J. Theory based scaling of edge turbulence and implications for the scrape-off layer width. United States: N. p., 2016. Web. doi:10.11578/1366750.
Myra, J.R., Russell, D.A., & Zweben, S.J. Theory based scaling of edge turbulence and implications for the scrape-off layer width. United States. doi:10.11578/1366750.
Myra, J.R., Russell, D.A., and Zweben, S.J. 2016. "Theory based scaling of edge turbulence and implications for the scrape-off layer width". United States. doi:10.11578/1366750. https://www.osti.gov/servlets/purl/1366750. Pub date:Tue Nov 01 00:00:00 EDT 2016
@article{osti_1366750,
title = {Theory based scaling of edge turbulence and implications for the scrape-off layer width},
author = {Myra, J.R. and Russell, D.A. and Zweben, S.J.},
abstractNote = {Turbulence and plasma parameter data from the National Spherical Torus Experiment NSTX [M. Ono, S.M. Kaye, Y.-K.M. Peng, G. Barnes et al., Nucl. Fusion 40, 557 (2000)] is examined and interpreted based on various theoretical estimates. In particular, quantities of interest for assessing the role of turbulent transport on the midplane scrape-off layer heat flux width are assessed. Because most turbulence quantities exhibit large scatter and little scaling within a given operation mode, this paper focuses on length and time scales and dimensionless parameters between operational modes including Ohmic, low (L), and high (H) modes using a large NSTX edge turbulence database [S.J. Zweben, W.M. Davis, S.M. Kaye, J.R. Myra et al., Nucl. Fusion 55, 093035 (2015)]. These are compared with theoretical estimates for drift and interchange rates, profile modification saturation levels, a resistive ballooning condition, and dimensionless parameters characterizing L and high H mode conditions. It is argued that the underlying instability physics governing edge turbulence in different operational modes is in fact similar, and is consistent with curvature-driven drift ballooning. Saturation physics, however, is dependent on the operational mode. Five dimensionless parameters for drift-interchange turbulence are obtained and employed to assess the important of turbulence in setting the scrape-off layer heat flux width lambda_q and its scaling. An explicit proportionality of the width lambda_q to safety factor and major radius (qR) is obtained under these conditions. Quantitative estimates and reduced model numerical simulations suggest that the turbulence mechanism is not negligible in determining lambda_q in NSTX, at least for high plasma current discharges.},
doi = {10.11578/1366750},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2016},
month = {11}
}

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Works referenced in this record:

Theory based scaling of edge turbulence and implications for the scrape-off layer width
journal, November 2016

  • Myra, J. R.; Russell, D. A.; Zweben, S. J.
  • Physics of Plasmas, Vol. 23, Issue 11
  • DOI: 10.1063/1.4966564

    Works referencing / citing this record:

    Theory based scaling of edge turbulence and implications for the scrape-off layer width
    journal, November 2016

    • Myra, J. R.; Russell, D. A.; Zweben, S. J.
    • Physics of Plasmas, Vol. 23, Issue 11
    • DOI: 10.1063/1.4966564