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An advection-diffusion model for cross-field runaway electron transport in perturbed magnetic fields

K. Sarkimaki ; E. Hirvijoki ; J. Decker ; J. Varje ; Taina Kurki-Suonio (Institutionen för fysik, Subatomär fysik och plasmafysik (Chalmers))
Plasma Physics and Controlled Fusion (0741-3335). Vol. 58 (2016), 12,
[Artikel, refereegranskad vetenskaplig]

Disruption-generated runaway electrons (RE) present an outstanding issue for ITER. The predictive computational studies of RE generation rely on orbit-averaged computations and, as such, they lack the effects from the magnetic field stochasticity. Since stochasticity is naturally present in post-disruption plasma, and externally induced stochastization offers a prominent mechanism to mitigate RE avalanche, we present an advection-diffusion model that can be used to couple an orbit-following code to an orbit-averaged tool in order to capture the cross-field transport and to overcome the latter's limitation. The transport coefficients are evaluated via a Monte Carlo method. We show that the diffusion coefficient differs significantly from the well-known Rechester-Rosenbluth result. We also demonstrate the importance of including the advection: it has a two-fold role both in modelling transport barriers created by magnetic islands and in amplifying losses in regions where the islands are not present.

Nyckelord: runaway electron, radial transport, stochastic magnetic field, advection, diffusion



Denna post skapades 2017-01-13.
CPL Pubid: 246862

 

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Institutioner (Chalmers)

Institutionen för fysik, Subatomär fysik och plasmafysik (Chalmers)

Ämnesområden

Fusion, plasma och rymdfysik

Chalmers infrastruktur