Impurity transport and bulk ion flow in a mixed collisionality stellarator plasma
Journal article, 2017

The accumulation of impurities in the core of magnetically confined plasmas, resulting from standard collisional transport mechanisms, is a known threat to their performance as fusion energy sources. Whilst the axisymmetric tokamak systems have been shown to benefit from the effect of temperature screening, that is an outward flux of impurities driven by the temperature gradient, impurity accumulation in stellarators was thought to be inevitable, driven robustly by the inward pointing electric field characteristic of hot fusion plasmas. We have shown in Helander et al. (Phys. Rev. Lett, vol. 118, 2017a, 155002) that such screening can in principle also appear in stellarators, in the experimentally relevant mixed collisionality regime, where a highly collisional impurity species is present in a low collisionality bulk plasma. Details of the analytic calculation are presented here, along with the effect of the impurity on the bulk ion flow, which will ultimately affect the bulk contribution to the bootstrap current.

Plasma flows

Plasma confinement

Fusion plasma


Sarah Newton

Chalmers, Physics, Subatomic and Plasma Physics

Culham Science Centre

Per Helander

Max Planck Society

Albert Mollén

Max Planck Society

Håkan Smith

Max Planck Society

Journal of Plasma Physics

0022-3778 (ISSN) 1469-7807 (eISSN)

Vol. 83 5 905830505

Subject Categories

Energy Engineering

Fusion, Plasma and Space Physics

Condensed Matter Physics



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