Reduced-MHD Simulations of Toroidally and Poloidally Localized ELMs

TL;DR

This study uses reduced-MHD simulations to analyze ELMs in the ASDEX Upgrade tokamak, revealing localized perturbations consistent with recent experimental observations and emphasizing the importance of high toroidal resolution.

Contribution

First detailed reduced-MHD simulations capturing localized ELM perturbations consistent with experimental solitary magnetic perturbations.

Findings

Toroidal mode numbers match observations.

Filament sizes and propagation speeds agree with experiments.

Localization of perturbations requires high toroidal resolution.

Abstract

We use the non-linear reduced-MHD code JOREK to study ELMs in the geometry of the ASDEX Upgrade tokamak. Toroidal mode numbers, poloidal filament sizes, and radial propagation speeds of filaments into the scrape-off layer are in good agreement with observations for type-I ELMs in ASDEX Upgrade. The observed instabilities exhibit a localization of perturbations which is compatible with the "solitary magnetic perturbations" recently discovered in ASDEX Upgrade [R.Wenninger et.al., Solitary Magnetic Perturbations at the ELM Onset, Nucl.Fusion, submitted]. This localization can only be described in numerical simulations with high toroidal resolution.