Predicting PDF tails of flux in plasma sheath region

TL;DR

This paper predicts the probability density function tails of flux in plasma sheath regions using a non-perturbative statistical approach, revealing non-Gaussian extreme value distributions caused by intermittent coherent structures.

Contribution

It introduces the first prediction of PDF tails in plasma sheath flux using instanton theory, highlighting the role of intermittency and non-Gaussian distributions.

Findings

PDF tails follow a modified Gumbel distribution

Non-Gaussian tails are due to intermittency from coherent structures

Enhanced tails over Gaussian predictions indicate extreme flux events

Abstract

This letter provides the first prediction of the probability density function (PDF) of flux $R$ in plasma sheath sheath region in magnetic fusion devices which is characterized by dynamical equations with exponential non-linearities. By using a non-perturbative statistical theory (instantons), the PDF tails of first moment are shown to be modified Gumbel distribution which represents a frequency distribution of the extreme values of the ensemble. The non-Gaussian PDF tails that are enhanced over Gaussian predictions are the result of intermittency caused by short lived coherent structures (instantons).