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

Abstract

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:

Churchill, R. M.  ^[1];

• Search DOE PAGES for author "Churchill, R. M."
• Search DOE PAGES for ORCID "0000-0001-5711-746X"

Chang, C. S.  ^[1];

• Search DOE PAGES for author "Chang, C. S."
• Search DOE PAGES for ORCID "0000-0002-3346-5731"

Ku, S.  ^[1];

• Search DOE PAGES for author "Ku, S."
• Search DOE PAGES for ORCID "0000-0002-9964-1208"

Dominski, J.  ^[1]

• Search DOE PAGES for author "Dominski, J."
• Search DOE PAGES for ORCID "0000-0001-9380-2544"

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+ Show Author Affiliations

1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Publication Date:

Wed Aug 30 00:00:00 EDT 2017

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:

1389873

Grant/Contract Number:  

AC02-09CH11466; AC02-05CH11231

Resource 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

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