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Title: The dominant micro-turbulence instabilities in the lower q95 high βp plasmas on DIII-D and predict-first extrapolation

Abstract

Large-radius internal transport barriers (ITB) are the signature of high βp scenarios on DIII-D. Previous studies show that a large Shafranov shift, rather the E x B shear, suppresses the turbulence and helps in the formation of the large-radius ITB. New gyrokinetic simulations suggest that the remaining micro-instabilities in lower q95 (<7.0), high βp ITB plasmas are drift wave instabilities, including the collisionless trapped electron mode in the core and ITB peak gradient region, the electron temperature gradient mode in the ITB peak gradient region and at the ITB foot and the ion temperature gradient mode at the ITB foot. Gyrokinetic simulation results qualitatively agree with the density fluctuation analysis from beam emission spectroscopy, which suggests the existence of a low-k ion mode at the ITB foot. As a result, the gyrokinetic simulations also predict that a larger Shafranov shift can overwhelm the driving sources for turbulence from the profile gradients at higher βN, leading to stronger turbulence suppression and stronger ITBs in lower q95, high βp plasmas.

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [4];  [3]; ORCiD logo [5];  [6]
+ Show Author Affiliations
  1. Oak Ridge Associated Univ., Oak Ridge, TN (United States); Chinese Academy of Sciences, Anhui (China)
  2. Univ. of California, San Diego, La Jolla, CA (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Univ. of Wisconsin-Madison, Madison, WI (United States)
  5. Chinese Academy of Sciences, Anhui (China)
  6. Princeton Univ., Princeton, NJ (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1578050
Grant/Contract Number:  
FC02-04ER54698; SC0010685; SC0018287
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 1; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; high βp scenario; micro-turbulence instabilities; predict-first extrapolation

Citation Formats

Ding, S., Jian, X., Garofalo, A. M., Yan, Z., McClenaghan, J., Guo, W., and Grierson, B. A. The dominant micro-turbulence instabilities in the lower q95 high βp plasmas on DIII-D and predict-first extrapolation. United States: N. p., 2019. Web. doi:10.1088/1741-4326/ab5152.
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Ding, S., Jian, X., Garofalo, A. M., Yan, Z., McClenaghan, J., Guo, W., & Grierson, B. A. The dominant micro-turbulence instabilities in the lower q95 high βp plasmas on DIII-D and predict-first extrapolation. United States. doi:10.1088/1741-4326/ab5152.
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Ding, S., Jian, X., Garofalo, A. M., Yan, Z., McClenaghan, J., Guo, W., and Grierson, B. A. Thu . "The dominant micro-turbulence instabilities in the lower q95 high βp plasmas on DIII-D and predict-first extrapolation". United States. doi:10.1088/1741-4326/ab5152. https://www.osti.gov/servlets/purl/1578050.
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@article{osti_1578050,
title = {The dominant micro-turbulence instabilities in the lower q95 high βp plasmas on DIII-D and predict-first extrapolation},
author = {Ding, S. and Jian, X. and Garofalo, A. M. and Yan, Z. and McClenaghan, J. and Guo, W. and Grierson, B. A.},
abstractNote = {Large-radius internal transport barriers (ITB) are the signature of high βp scenarios on DIII-D. Previous studies show that a large Shafranov shift, rather the E x B shear, suppresses the turbulence and helps in the formation of the large-radius ITB. New gyrokinetic simulations suggest that the remaining micro-instabilities in lower q95 (<7.0), high βp ITB plasmas are drift wave instabilities, including the collisionless trapped electron mode in the core and ITB peak gradient region, the electron temperature gradient mode in the ITB peak gradient region and at the ITB foot and the ion temperature gradient mode at the ITB foot. Gyrokinetic simulation results qualitatively agree with the density fluctuation analysis from beam emission spectroscopy, which suggests the existence of a low-k ion mode at the ITB foot. As a result, the gyrokinetic simulations also predict that a larger Shafranov shift can overwhelm the driving sources for turbulence from the profile gradients at higher βN, leading to stronger turbulence suppression and stronger ITBs in lower q95, high βp plasmas.},
doi = {10.1088/1741-4326/ab5152},
journal = {Nuclear Fusion},
number = 1,
volume = 60,
place = {United States},
year = {2019},
month = {11}
}
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DOI:  10.1088/1741-4326/ab5152
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