Experimental evidence of the non-diffusive avalanche-like electron heat transport events and their dynamical interaction with the shear flow structure

TL;DR

This paper provides experimental evidence that non-diffusive avalanche-like electron heat transport events are common in tokamak core plasmas and interact dynamically with shear flow structures, revealing mesoscale transport mechanisms.

Contribution

It demonstrates the prevalence of avalanche-like heat transport events and their interaction with shear flows in tokamak plasmas without MHD instabilities, highlighting their mesoscale nature.

Findings

Avalanche-like events are prevalent in low confinement tokamak plasmas.

Electron temperature profile corrugations are linked to shear flow layers.

Profile corrugations have a width of about 45ρ_i, indicating mesoscale structures.

Abstract

We present experimental observations suggesting that the non-diffusive avalanche-like events are a prevalent and universal process of the electron turbulent heat transport in tokamak core plasmas. They are observed in the low confinement mode and the weak internal transport barrier tokamak plasmas in the absence of magnetohydrodynamic instabilities. In addition, the electron temperature profile corrugation, which indicates the existence of the $E \times B$ shear flow layers, is clearly demonstrated as well as their dynamical interaction with the avalanche-like events. The measured width of the profile corrugation is around $45\rho_i$, which implies the mesoscale nature of the structure.