Velocity shear, turbulent saturation, and steep plasma gradients in the scrape-off layer of inner-wall limited tokamaks

Halpern, Federico D.; Ricci, Paolo

doi:10.1088/1741-4326/aa4eb6

Velocity shear, turbulent saturation, and steep plasma gradients in the scrape-off layer of inner-wall limited tokamaks

Journal Article · Mon Dec 19 00:00:00 EST 2016 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aa4eb6· OSTI ID:1345664

Halpern, Federico D. ^[1]; Ricci, Paolo ^[2]

Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); General Atomics, San Diego, CA (United States); General Atomics
Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland)

The narrow power decay-length (λ_q), recently found in the scrape-off layer (SOL) of inner wall limited (IWL) discharges in tokamaks, is studied using 3D, flux-driven, global two fluid turbulence simulations. The formation of the steep plasma profiles is found to arise due to radially sheared E×B poloidal flows. A complex interaction between sheared flows and parallel plasma currents outflowing into the sheath regulates the turbulent saturation, determining the transport levels. We quantify the effects of sheared flows, obtaining theoretical estimates in agreement with our non-linear simulations. As a result, analytical calculations suggest that the IWL λ_q is roughly equal to the turbulent correlation length.

View Accepted Manuscript (DOE)

Research Organization:: Computational Simulation Centre of International Fusion Energy Research Centre (IFERC-CSC), Aomori (Japan)

Sponsoring Organization:: USDOE

Grant/Contract Number:: FC02-04ER54698

OSTI ID:: 1345664

Alternate ID(s):: OSTI ID: 22925626

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 3 Vol. 57; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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Impurity seeding for suppression of the near scrape-off layer heat flux feature in tokamak limited plasmas Nespoli, F.; Labit, B.; Furno, I. Physics of Plasmas, Vol. 25, Issue 5 https://doi.org/10.1063/1.5023201	journal	May 2018
Shaping effects on scrape-off layer plasma turbulence: A rigorous validation of three-dimensional simulations against TCV measurements Riva, F.; Tsui, C. K.; Boedo, J. A. Physics of Plasmas, Vol. 27, Issue 1 https://doi.org/10.1063/1.5123451	journal	January 2020
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Understanding and suppressing the near scrape-off layer heat flux feature in inboard-limited plasmas in TCV Nespoli, F.; Labit, B.; Furno, I. Nuclear Fusion, Vol. 57, Issue 12 https://doi.org/10.1088/1741-4326/aa84e0	journal	September 2017
Tokamak Edge Plasma Turbulence Interaction with Magnetic X-Point in 3D Global Simulations Galassi, Davide; Ciraolo, Guido; Tamain, Patrick Fluids, Vol. 4, Issue 1 https://doi.org/10.3390/fluids4010050	journal	March 2019
Impurity seeding for suppression of the near Scrape-Off Layer heat flux feature in tokamak limited plasmas Nespoli, F.; Labit, B.; Furno, I. arXiv https://doi.org/10.48550/arxiv.1712.00951	text	January 2017

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