Optimization of flux-surface density variation in stellarator plasmas with respect to the transport of collisional impurities
Artikel i vetenskaplig tidskrift, 2019

Avoiding impurity accumulation is a requirement for steady-state stellarator operation. The accumulation of impurities can be heavily affected by variations in their density on the flux-surface. Using recently derived semi-analytic expressions for the transport of a collisional impurity species with high-Z and flux-surface density-variation in the presence of a low-collisionality bulk ion species, we numerically optimize the impurity density-variation on the flux-surface to minimize the radial peaking factor of the impurities. These optimized density-variations can reduce the core impurity density by 0.75^Z (with Z the impurity charge number) in the large helical device case considered here, and by 0.89^Z in a Wendelstein 7-X standard configuration case. On the other hand, when the same procedure is used to find density-variations that maximize the peaking factor, it is notably increased compared to the case with no density-variation. This highlights the potential importance of measuring and controlling these variations in experiments.


impurity transport

fusion plasma

collisional transport


Stefan Buller

Chalmers, Fysik, Subatomär fysik och plasmafysik

Håkan Smith


Albert Mollén

Chalmers, Fysik, Subatomär fysik och plasmafysik

Sarah Newton

Chalmers, Fysik, Subatomär fysik och plasmafysik

Istvan Pusztai

Chalmers, Fysik, Subatomär fysik och plasmafysik

Nuclear Fusion

00295515 (ISSN) 17414326 (eISSN)

Vol. 59 6 066028

Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium (EUROfusion)

Europeiska kommissionen (EU), 2014-01-01 -- 2019-01-01.


Hållbar utveckling




Grundläggande vetenskaper


Fusion, plasma och rymdfysik



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