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arXiv · 2610.30343

A novel mechanism for spontaneous ExB shear layer formation in scrape-off-layer plasmas

Brendan Shanahan·Eduardo Rodriguez
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Abstract

We present a novel mechanism for spontaneous shear-flow generation in the scrape-off layer (SOL) of magnetically confined plasmas, arising at abrupt changes in the sheath connection length $L_\parallel$. Such transitions occur naturally in the Wendelstein 7-X stellarator. Applying a critical balance treatment for interchange turbulence, we find that $L_\parallel$ sets the equilibrium pressure gradient and hence the radial electric field away from the transition, producing an $E\times B$ shear around the transition comparable to the turbulence growth rate. High-fidelity simulations are shown to be consistent with the theoretical prediction.

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Brendan Shanahan, Eduardo Rodriguez. 2026-10-21. A novel mechanism for spontaneous ExB shear layer formation in scrape-off-layer plasmas. https://arxiv.org/abs/2610.30343

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