Fast-moving electrostatic solitons in a plasma with turbulence heating

TL;DR

This paper demonstrates that in turbulent plasma environments, electrostatic solitons can form at velocities much higher than the ion-sound speed, especially in protoplanetary disk 'dead zones' with non-Maxwellian electron distributions.

Contribution

It introduces a novel mechanism for high-velocity electrostatic soliton formation in turbulent, non-Maxwellian plasma conditions relevant to astrophysical disks.

Findings

High-velocity solitons can form in turbulent plasma with non-Maxwellian electrons.

Solitons may serve as an energy equilibration mechanism via decay and radiation.

Relevance to protoplanetary disk 'dead zones' with electron heating.

Abstract

In this work, it is shown that electrostatic solitons in a plasma with turbulent heating of the electrons through an accelerating electric field can form with very high velocities, reaching up to several order of magnitudes larger than the equilibrium ion-sound speed. The possible parameter regime, where this work may be relevant, can be found in the so-called "dead zones" of a protoplanetary disk. Though these zones are stable to magnetorotational instability, the resultant turbulence can in fact heat the electrons making them follow a highly non- Maxwellian velocity distribution. We show that these fast-moving solitons can reach very high velocities. With electron velocity distribution described by the Davydov distribution function, we argue that these solitons can be an effective mechanism for energy equilibration in such a situation through soliton decay and radiation.