The Ambipolar electric field in multispecies plasma atmospheres: effects of alpha particles and stochastic heating
Abstract
We investigate stationary states of a collisionless, gravitationally stratified plasma atmosphere composed of electrons, protons, and alpha particles by extending Pannekoek--Rosseland theory to multispecies and multi-temperature plasmas. Starting from Liouville's theorem, we derive the self-consistent ambipolar electric field from kinetic equilibrium and charge neutrality. For a single-temperature atmosphere, we obtain analytical expressions for the ambipolar field, show its dependence on alpha-particle abundance, and determine the relative stratification of the three species. A first-order analytical approximation to the electrostatic potential accurately reproduces the numerical solution. We then generalize the formalism to multi-temperature plasmas generated by stochastic boundary heating, representing the stationary distribution as a superposition of Maxwellian populations. Gravitational filtering produces non-exponential density profiles and increasing temperatures with altitude, while preserving the relative species stratification, with alpha particles most strongly stratified and protons least. The ambipolar electric field contains a dominant gravitational contribution, corresponding to the generalized Pannekoek--Rosseland field, and a thermoelectric contribution arising from species-dependent temperature gradients, which accounts for its non-monotonic structure. These results provide a framework for studying the combined effects of plasma composition and stochastic heating in gravitationally stratified astrophysical plasmas.
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BibTeX
@misc{barbieri2026ambipolar,
title = {{The Ambipolar electric field in multispecies plasma atmospheres: effects of alpha particles and stochastic heating}},
author = {Luca Barbieri and Pascal Démoulin and Daniel Verscharen},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.12014},
eprint = {2608.12014},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.12014},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Ambipolar electric field in multispecies plasma atmospheres: effects of alpha particles and stochastic heating
AU - Luca Barbieri
AU - Pascal Démoulin
AU - Daniel Verscharen
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2608.12014
UR - https://arxiv.org/abs/2608.12014
AB - We investigate stationary states of a collisionless, gravitationally stratified plasma atmosphere composed of electrons, protons, and alpha particles by extending Pannekoek--Rosseland theory to multispecies and multi-temperature plasmas. Starting from Liouville's theorem, we derive the self-consistent ambipolar electric field from kinetic equilibrium and charge neutrality. For a single-temperature atmosphere, we obtain analytical expressions for the ambipolar field, show its dependence on alpha-particle abundance, and determine the relative stratification of the three species. A first-order analytical approximation to the electrostatic potential accurately reproduces the numerical solution. We then generalize the formalism to multi-temperature plasmas generated by stochastic boundary heating, representing the stationary distribution as a superposition of Maxwellian populations. Gravitational filtering produces non-exponential density profiles and increasing temperatures with altitude, while preserving the relative species stratification, with alpha particles most strongly stratified and protons least. The ambipolar electric field contains a dominant gravitational contribution, corresponding to the generalized Pannekoek--Rosseland field, and a thermoelectric contribution arising from species-dependent temperature gradients, which accounts for its non-monotonic structure. These results provide a framework for studying the combined effects of plasma composition and stochastic heating in gravitationally stratified astrophysical plasmas.
ER -