On the velocity drift between ions in the solar atmosphere

TL;DR

This paper introduces a sophisticated 3D multi-fluid simulation code to study velocity drifts between ions in the solar atmosphere, revealing how wave energy can dissipate through ion interactions and influence solar plasma dynamics.

Contribution

The development of the Ebysus multi-fluid, multi-species numerical code enables detailed investigation of ion velocity drifts and their dissipation in the solar atmosphere.

Findings

Ion velocity drifts can be driven by high-frequency Alfvén waves.

Different ion species can exhibit anti-phase rotational motions.

Wave kinetic energy can be converted into thermal energy through ion interactions.

Abstract

The solar atmosphere is composed of many species which are populated at different ionization and excitation levels. The upper chromosphere, transition region, and corona are nearly collisionless. Consequently, slippage between, for instance, ions and neutral particles, or interactions between separate species, may play important roles. We have developed a 3D multi-fluid and multi-species numerical code (Ebysus) to investigate such effects. Ebysus is capable of treating species (e.g., hydrogen, helium, etc) and fluids (neutrals, excited and ionized elements) separately, including non-equilibrium ionization, momentum exchange, radiation, thermal conduction, and other complex processes in the solar atmosphere. Treating different species as different fluids leads to drifts between different ions and an electric field that couples these motions. The coupling for two ionized fluids can lead to an anti-phase rotational motion between them. Different ionized species and momentum exchange can dissipate this velocity drift, i.e., convert wave kinetic energy into thermal energy. High frequency Alfv\'en waves driven by, e.g., reconnection thought to occur in the solar atmosphere, can drive such multi-ion velocity drifts.