DREAM: a fluid-kinetic framework for tokamak disruption runaway electron simulations

TL;DR

This paper introduces DREAM, a computational framework that enables self-consistent, fluid-kinetic simulations of runaway electron behavior during tokamak disruptions, aiding in disruption mitigation strategies.

Contribution

DREAM is a novel, efficient numerical tool that combines fluid and kinetic models to simulate plasma cooling and runaway electron dynamics during disruptions.

Findings

DREAM can simulate disruption scenarios with varying complexity levels.

The framework provides insights into electron current, heat, and density evolution.

It demonstrates the importance of kinetic effects in runaway electron dynamics.

Abstract

Avoidance of the harmful effects of runaway electrons (REs) in plasma-terminating disruptions is pivotal in the design of safety systems for magnetic fusion devices. Here, we describe a computationally efficient numerical tool, that allows for self-consistent simulations of plasma cooling and associated RE dynamics during disruptions. It solves flux-surface averaged transport equations for the plasma density, temperature and poloidal flux, using a bounce-averaged kinetic equation to self-consistently provide the electron current, heat, density and RE evolution, as well as the electron distribution function. As an example, we consider disruption scenarios with material injection and compare the electron dynamics resolved with different levels of complexity, from fully kinetic to fluid modes.