# Nonlinear reconnecting edge localized modes in tokamaks

## TL;DR

This paper uses 3D resistive MHD simulations to study nonlinear edge localized modes in tokamaks, revealing the formation of filament structures and their role in current relaxation and plasma edge dynamics.

## Contribution

It introduces a detailed simulation-based analysis of nonlinear ELMs, highlighting the formation of filament structures and their impact on edge current relaxation.

## Key findings

- Formation of filament-like structures during ELMs
- Repetitive relaxation cycles expelling and relaxing edge current
- Dynamo action relaxes current density and creates edge current holes

## Abstract

Nonlinear edge localized modes in a tokamak are examined using global three-dimensional resistive magnetohydrodynamics simulations. Coherent current-carrying filament (ribbon-like) structures wrapped around the torus are nonlinearly formed due to nonaxisymmetric reconnecting current sheet instabilities, the so called peeling-like edge localized modes. These fast growing modes saturate by breaking axisymmetric current layers isolated near the plasma edge and go through repetitive relaxation cycles by expelling current radially outward and relaxing it back. The local bi-directional fluctuation-induced electromotive force (emf) from the edge localized modes, the dynamo action, relaxes the axisymmetric current density and forms current holes near the edge.