Parallel impurity dynamics in the TJ-II stellarator

Abstract

We review in a tutorial fashion some of the causes of impurity density variations along field lines and radial impurity transport in the moment approach framework. An explicit and compact form of the parallel inertia force valid for arbitrary toroidal geometry and magnetic coordinates is derived and shown to be non-negligible for typical TJ-II plasma conditions. In the second part of the article, we apply the fluid model including main ion-impurity friction and inertia to observations of asymmetric emissivity patterns in neutral beam heated plasmas of the TJ-II stellarator. The model is able to explain qualitatively several features of the radiation asymmetry, both in stationary and transient conditions, based on the calculated in-surface variations of the impurity density.

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Cited by in corpus (4)

• The effect of tangential drifts on neoclassical transport in stellarators close to omnigeneity
• Moderation of neoclassical impurity accumulation in high temperature plasmas of helical devices
• Electrostatic potential variations on stellarator magnetic surfaces in low collisionality regimes
• Large tangential electric fields in plasmas close to temperature screening