Diffusion in plasma: the Hall effect, compositional waves, and chemical spots

TL;DR

This paper explores how electric currents and the Hall effect induce diffusion in plasma, leading to chemical inhomogeneities and element spots, and discusses associated compositional waves under high magnetic pressure conditions.

Contribution

It introduces a mechanism of current-driven diffusion that can create chemical inhomogeneities and element spots in plasma, relevant for both laboratory and astrophysical contexts.

Findings

Diffusion caused by electric current and Hall effect can form chemical inhomogeneities.

Current-driven diffusion can generate element spots in plasma.

Existence of compositional waves under high magnetic pressure conditions.

Abstract

We consider diffusion caused by a combined influence of the electric current and the Hall effect, and argue that such diffusion can form inhomogeneities of the chemical composition in plasma. The considered mechanism can be responsible for a formation of element spots in laboratory and astrophysical plasmas. This current-driven diffusion can be accompanied by propagation of a particular type waves in which the impurity number density oscillate alone. These compositional waves exist if the magnetic pressure in plasma is much greater than the gas pressure,