Reduction of transport due to magnetic shear in gyrokinetic simulations of the scrape-off layer

TL;DR

This paper investigates how magnetic shear influences turbulence and transport in the scrape-off layer using electromagnetic gyrokinetic simulations, revealing that stronger shear reduces perpendicular transport but increases peak fluxes.

Contribution

The study introduces a helical geometry model with magnetic shear for gyrokinetic simulations, providing new insights into shear's impact on transport in the scrape-off layer.

Findings

Stronger magnetic shear reduces perpendicular transport.

Electromagnetic effects slightly increase transport in strong shear cases.

Higher peak particle and heat fluxes are observed with increased shear.

Abstract

The effect of varying magnetic shear on scrape-off layer turbulence and profiles is studied via electromagnetic gyrokinetic simulations of a helical scrape-off layer model. We develop a model helical geometry with magnetic shear and a corresponding field-aligned coordinate system, which is used for simulations with the Gkeyll code. We find that perpendicular transport is reduced in cases with stronger shear, resulting in higher peak particle and heat fluxes to the endplates. Electromagnetic effects slightly increase transport in strong shear cases.