Dynamics of 3D isolated thermal filaments

TL;DR

This study uses 3D simulations to explore how electron thermal physics influences isolated filament dynamics, revealing that temperature effects significantly alter filament propagation and confinement in the SOL region.

Contribution

It introduces a dynamic electron temperature into filament simulations, showing how thermal effects modify filament motion and confinement in the edge plasma.

Findings

Thermal effects increase bi-normal filament propagation.

Thermal effects decrease radial filament velocity.

Filaments with larger temperature perturbations are more confined to the near SOL.

Abstract

Simulations have been carried out to establish how electron thermal physics, introduced in the form of a dynamic electron temperature, affects isolated filament motion and dynamics in 3D. It is found that thermal effects impact filament motion in two major ways when the filament has a significant temperature perturbation compared to its density perturbation: They lead to a strong increase in filament propagation in the bi-normal direction and a significant decrease in net radial propagation. Both effects arise from the temperature dependence of the sheath current which leads to a non-uniform floating potential, with the latter effect supplemented by faster pressure loss. The reduction in radial velocity can only occur when the filament cross-section loses angular symmetry. The behaviour is observed across different filament sizes and suggests that filaments with much larger temperature perturbations than density perturbations are more strongly confined to the near SOL region.