Electron heating in 2-D: combining Fermi-Ulam acceleration and magnetic-moment non-adiabaticity in a mirror-configuration plasma

TL;DR

This paper introduces a new 2-D electron acceleration mechanism in mirror-configuration plasmas, combining Fermi-Ulam acceleration with magnetic-moment non-adiabaticity, leading to a Maxwellian energy distribution and improved confinement.

Contribution

It presents a novel 2-D model that integrates Fermi-Ulam acceleration and magnetic-moment non-adiabaticity, enhancing understanding of electron confinement in mirror plasmas.

Findings

Electron energy distribution becomes Maxwellian due to combined effects.

Non-adiabaticity reduces loss-cone escape, improving confinement.

Theoretical model aligns with experimental data.

Abstract

We analyze a new mechanism for the creation and confinement of energetic electrons in a mirror-configuration plasma. A Fermi-Ulam-type process, driven by end-localized coherent electrostatic oscillations, provides axial acceleration while a natural non-adiabaticity of {\mu} provides phase decorrelation and energy isotropization. This novel 2-D combination causes the electron energy distribution function, calculated with a diffusive-loss model, to assume a Maxwellian shape with the {\mu} non-adiabaticity reducing loss-cone escape and annulling the absolute-barrier energy-limiting Chirikov criterion of lower dimensional models. The theoretical predictions are compared with data from an experiment.