Effects of intermittency on turbulent transport in magnetized plasmas

TL;DR

This paper investigates how intermittent turbulence, characterized by non-Gaussian electric potential distributions, inhibits turbulent transport in magnetized plasmas, with effects depending on poloidal velocity and correlation time.

Contribution

It provides an analytical and numerical analysis of the impact of intermittency on turbulent transport, highlighting the linear inhibition linked to kurtosis and its dependence on plasma parameters.

Findings

Intermittency inhibits diffusion linearly via kurtosis.

Susceptibility depends on poloidal velocity and correlation time.

Intermittency does not alter Kubo number scaling in the strong regime.

Abstract

We analyze how the turbulent transport of $\mathbf{E}\times \mathbf{B}$ type in magnetically confined plasmas is affected by intermittent features of turbulence. The latter are captured by the non-Gaussian distribution $P(\phi)$ of the turbulent electric potential $\phi$. Our analysis is performed at an analytical level and confirmed numerically using two statistical approaches. We have found that the diffusion is inhibited linearly by intermittency, mainly via the kurtosis of the distribution $P(\phi)$. The associated susceptibility for this linear process is shown to be dependent on the poloidal velocity $V_p$ and on the correlation time $\tau_c$ with a maxima at the time-of-flight $\tau_{fl}$. Intermittency does not affect the Kubo number scaling in the strong regime.