Non-local approach to kinetic effects on parallel transport in fluid models of the scrape-off layer

TL;DR

This paper introduces a non-local fluid model that better captures kinetic effects on parallel electron heat-flux in the scrape-off layer, outperforming traditional diffusive models with flux limiters.

Contribution

The study presents a non-local model integrated into BOUT++ that improves simulation accuracy of kinetic effects in the scrape-off layer compared to standard diffusive approaches.

Findings

Non-local model enhances electron temperature gradients.

Compared to flux limiters, non-local approach captures kinetic effects more effectively.

Implementation is suitable for 3D turbulent transport simulations.

Abstract

By using a non-local model, fluid simulations can capture kinetic effects in the parallel electron heat-flux better than is possible using flux limiters in the usual diffusive models. Non-local and diffusive models are compared using a test case representative of an ELM crash in the JET SOL, simulated in one dimension. The non-local model shows substantially enhanced electron temperature gradients, which cannot be achieved using a flux limiter. The performance of the implementation, in the BOUT++ framework, is also analysed to demonstrate its suitability for application in three-dimensional simulations of turbulent transport in the SOL.