Resistive Hose modes in Tokamak Runaway Electron Beams

TL;DR

This paper investigates resistive hose instabilities in tokamak runaway electron beams, revealing their rapid growth at high resistivity and their decoupling from plasma response, with implications for plasma temperature regimes.

Contribution

It provides a linear analysis showing resistive hose modes grow faster than tearing modes and decouple from plasma response in runaway electron beams.

Findings

Resistive hose instabilities grow faster than tearing modes at high resistivity.

Resistive hose decouples from plasma response in the models.

Estimated plasma temperature where hose growth dominates tearing.

Abstract

Beams of energetic runaway electrons are generated during disruptions in tokamaks, and fluid models are used to study their effects on macroscale dynamics. Linear computations of a massless, runaway electron beam coupled to MHD plasma show that resistive hose instabilities grow faster than tearing modes at large resistivity. Eigenvalue results with reduced models of the resistive hose instability are compared with results from the full MHD and beam system, showing that the resistive hose decouples from any plasma response. An estimate of plasma temperature at which growth of the resistive hose dominates tearing for post-disruption DIII-D plasma parameters is in a physically relevant regime