Impurity Transport in a Mixed-Collisionality Stellarator Plasma
Artikel i vetenskaplig tidskrift, 2017

A potential threat to the performance of magnetically confined fusion plasmas is the problem of impurity accumulation, which causes the concentration of highly charged impurity ions to rise uncontrollably in the center of the plasma and spoil the energy confinement by excessive radiation. It has long been thought that the collisional transport of impurities in stellarators always leads to such an accumulation (if the electric field points inwards, which is usually the case), whereas tokamaks, being axisymmetric, can benefit from "temperature screening," i.e., an outward flux of impurities driven by the temperature gradient. Here it is shown, using analytical techniques supported by results from a new numerical code, that such screening can arise in stellarator plasmas, too, and indeed does so in one of the most relevant operating regimes, where the impurities are highly collisional while the bulk plasma is at low collisionality.

Diffusion

Neoclassical Transport

Författare

P. Helander

Max Planck-institutet

Sarah Newton

Chalmers, Fysik, Subatomär fysik och plasmafysik

Albert Mollén

Max Planck-institutet

Håkan Smith

Max Planck-institutet

Physical Review Letters

0031-9007 (ISSN) 1079-7114 (eISSN)

Vol. 118 155002 - 155002

Ämneskategorier

Fusion, plasma och rymdfysik

DOI

10.1103/PhysRevLett.118.155002