Collisional transport of impurities with flux-surface varying density in stellarators
Artikel i vetenskaplig tidskrift, 2018

High-Z impurities in magnetic-confinement devices are prone to develop density variations on the flux surface, which can significantly affect their transport. In this paper, we generalize earlier analytic stellarator calculations of the neoclassical radial impurity flux in the mixed-collisionality regime (collisional impurities and low-collisionality bulk ions) to include the effect of such flux-surface variations. We find that only in the homogeneous density case is the transport of highly collisional impurities (in the Pfirsch-Schlhter regime) independent of the radial electric field. We study these effects for a Wendelstein 7-X (W7-X) vacuum field, with simple analytic models for the potential perturbation, under the assumption that the impurity density is given by a Boltzmann response to a perturbed potential. In the W7-X case studied, we find that larger amplitude potential perturbations cause the radial electric field to dominate the transport of the impurities. In addition, we find that classical impurity transport can be larger than the neoclassical transport in W7-X.

fusion plasma

plasma confinement

Författare

Stefan Buller

Chalmers, Fysik, Subatomär fysik och plasmafysik

H. M. Smith

Max Planck-institutet

P. Helander

Max Planck-institutet

A. Mollen

Max Planck-institutet

S. L. Newton

Culham Science Centre

Istvan Pusztai

Chalmers, Fysik, Subatomär fysik och plasmafysik

Journal of Plasma Physics

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

Vol. 84 4 905840409

Ämneskategorier

Meteorologi och atmosfärforskning

Fusion, plasma och rymdfysik

Den kondenserade materiens fysik

DOI

10.1017/S0022377818000867

Mer information

Senast uppdaterat

2018-11-30