Generalized collision operator for fast electrons interacting with partially ionized impurities
Artikel i vetenskaplig tidskrift, 2018

Accurate modelling of the interaction between fast electrons and partially ionized atoms is important for evaluating tokamak disruption mitigation schemes based on material injection. This requires accounting for the effect of screening of the impurity nuclei by the cloud of bound electrons. In this paper, we generalize the Fokker–Planck operator in a fully ionized plasma by accounting for the effect of screening. We detail the derivation of this generalized operator, and calculate the effective ion length scales, needed in the components of the collision operator, for a number of ion species commonly appearing in fusion experiments. We show that for high electric fields, the secondary runaway growth rate can be substantially larger than in a fully ionized plasma with the same effective charge, although the growth rate is significantly reduced at near-critical electric fields. Furthermore, by comparison with the Boltzmann collision operator, we show that the Fokker–Planck formalism is accurate even for large impurity content.

runaway electrons

fusion plasma

Författare

Linnea Hesslow

Chalmers, Fysik, Subatomär fysik och plasmafysik

Ola Embréus

Chalmers, Fysik, Subatomär fysik och plasmafysik

Mathias Hoppe

Chalmers, Fysik, Subatomär fysik och plasmafysik

Timothy Dubois

Chalmers, Fysik, Subatomär fysik och plasmafysik

Gergely Papp

Max Planck-institutet

Martin Rahm

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Tünde Fülöp

Chalmers, Fysik, Subatomär fysik och plasmafysik

Journal of Plasma Physics

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

Vol. 84 6 905840605

Skena och skina

Europeiska kommissionen (Horisont 2020), 2015-10-01 -- 2020-09-30.

Skenande elektroner i fusionsplasmor

Vetenskapsrådet (VR), 2015-01-01 -- 2018-12-31.

Ämneskategorier

Atom- och molekylfysik och optik

Fusion, plasma och rymdfysik

DOI

10.1017/S0022377818001113

Mer information

Senast uppdaterat

2019-08-27