An advection-diffusion model for cross-field runaway electron transport in perturbed magnetic fields
Abstract
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 stochasiticity 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.
Keywords
Cite
@article{arxiv.1606.04409,
title = {An advection-diffusion model for cross-field runaway electron transport in perturbed magnetic fields},
author = {Konsta Särkimäki and Eero Hirvijoki and Joan Decker and Jari Varje and Taina Kurki-Suonio},
journal= {arXiv preprint arXiv:1606.04409},
year = {2017}
}