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Title: Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation

Understanding the multi-scale neoclassical and turbulence physics in the edge region (pedestal + scrape-off layer (SOL)) is required in order to reliably predict performance in future fusion devices. We explore turbulent characteristics in the edge region from a multi-scale neoclassical and turbulent XGC1 gyrokinetic simulation in a DIII-D like tokamak geometry, here excluding neutrals and collisions. For an H-mode type plasma with steep pedestal, it is found that the electron density fluctuations increase towards the separatrix, and stay high well into the SOL, reaching a maximum value of $$\delta {n}_{e}/{\bar{n}}_{e}\sim 0.18$$. Blobs are observed, born around the magnetic separatrix surface and propagate radially outward with velocities generally less than 1 km s –1. Strong poloidal motion of the blobs is also present, near 20 km s –1, consistent with E × B rotation. The electron density fluctuations show a negative skewness in the closed field-line pedestal region, consistent with the presence of 'holes', followed by a transition to strong positive skewness across the separatrix and into the SOL. These simulations indicate that not only neoclassical phenomena, but also turbulence, including the blob-generation mechanism, can remain important in the steep H-mode pedestal and SOL. Lastly, qualitative comparisons will be made to experimental observations.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Grant/Contract Number:
AC02-09CH11466; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 10; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; pedestal; turbulence; blobs; scrape-off-layer; tokamak plasma; transport; asdex; mode; devices
OSTI Identifier:
1389873

Churchill, R. M., Chang, C. S., Ku, S., and Dominski, J.. Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation. United States: N. p., Web. doi:10.1088/1361-6587/aa7c03.
Churchill, R. M., Chang, C. S., Ku, S., & Dominski, J.. Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation. United States. doi:10.1088/1361-6587/aa7c03.
Churchill, R. M., Chang, C. S., Ku, S., and Dominski, J.. 2017. "Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation". United States. doi:10.1088/1361-6587/aa7c03. https://www.osti.gov/servlets/purl/1389873.
@article{osti_1389873,
title = {Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation},
author = {Churchill, R. M. and Chang, C. S. and Ku, S. and Dominski, J.},
abstractNote = {Understanding the multi-scale neoclassical and turbulence physics in the edge region (pedestal + scrape-off layer (SOL)) is required in order to reliably predict performance in future fusion devices. We explore turbulent characteristics in the edge region from a multi-scale neoclassical and turbulent XGC1 gyrokinetic simulation in a DIII-D like tokamak geometry, here excluding neutrals and collisions. For an H-mode type plasma with steep pedestal, it is found that the electron density fluctuations increase towards the separatrix, and stay high well into the SOL, reaching a maximum value of $\delta {n}_{e}/{\bar{n}}_{e}\sim 0.18$. Blobs are observed, born around the magnetic separatrix surface and propagate radially outward with velocities generally less than 1 km s–1. Strong poloidal motion of the blobs is also present, near 20 km s–1, consistent with E × B rotation. The electron density fluctuations show a negative skewness in the closed field-line pedestal region, consistent with the presence of 'holes', followed by a transition to strong positive skewness across the separatrix and into the SOL. These simulations indicate that not only neoclassical phenomena, but also turbulence, including the blob-generation mechanism, can remain important in the steep H-mode pedestal and SOL. Lastly, qualitative comparisons will be made to experimental observations.},
doi = {10.1088/1361-6587/aa7c03},
journal = {Plasma Physics and Controlled Fusion},
number = 10,
volume = 59,
place = {United States},
year = {2017},
month = {8}
}