Turbulent broadening of electron heat-flux width in electromagnetic gyrokinetic simulations of a helical scrape-off layer model

Mandell, N. R.; Hammett, G. W.; Hakim, A.; Francisquez, M.

doi:10.1063/5.0082486

Turbulent broadening of electron heat-flux width in electromagnetic gyrokinetic simulations of a helical scrape-off layer model

Journal Article · Wed Apr 20 00:00:00 EDT 2022 · Physics of Plasmas

DOI:https://doi.org/10.1063/5.0082486· OSTI ID:1887978

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Princeton University, NJ (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Here, we demonstrate that cross field transport in the scrape-off layer (SOL) can be moderately increased by electromagnetic effects in high-beta regimes, resulting in broadening of the electron heat-flux width on the endplates. This conclusion is taken from full- f electromagnetic gyrokinetic simulations of a helical SOL model that roughly approximates the SOL of the National Spherical Torus Experiment. The simulations have been performed with the Gkeyll code, which recently became the first code to demonstrate the capability to simulate electromagnetic gyrokinetic turbulence on open magnetic field lines with sheath boundary conditions. We scan the source rate and thus β, so that the normalized pressure gradient (the MHD ballooning parameter $α ∝ ∂β/∂r ∝ β/Lρ$) is scanned over an experimentally relevant range, α = 0.3 - 1.5. While there is little change in the pressure gradient scale length L_p near the midplane as beta is increased, a 10% increase in cross field transport near the midplane results in an increase in the electron heat-flux width λ_q and a 25% reduction of the peak electron heat flux to the endplates.

View Accepted Manuscript (DOE)

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: Multiscale Gyrokinetic Turbulence (MGK); USDOE; USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: AC02-09CH11466; SC0014664

OSTI ID:: 1887978

Alternate ID(s):: OSTI ID: 1864084

Journal Information:: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 29; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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