Particle-In-Cell Modeling of Martian Magnetic Cusps and Their Role in Enhancing Nightside Ionospheric Ion Escape

A.R. Poppe*, D. A. Brain, Yaxue Dong, Shaosui Xu, Riku Järvinen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Amongst various escape channels, ion outflow is a major contributor to atmospheric loss at Mars over geologic time. On Mars' nightside, observations have indicated that cusp regions within crustal magnetic fields are associated with phenomena such as accelerated particle populations, discrete auroral emissions, and ionospheric outflow; however, the kinetic physics occurring within crustal magnetic cusps is poorly understood. Here, we present 1.5-dimensional particle-in-cell simulations of magnetospheric-ionospheric interactions within martian crustal magnetic cusp regions of varying strength. Simulation results demonstrate the formation of quasi-static, field-aligned potentials pointing away from Mars that accelerate electrons into the martian atmosphere while accelerating ions away, thereby enhancing ionospheric escape. Escaping ionospheric flux scales with crustal field strength, with 160 nT crustal fields yielding >2× the ion escape flux than in the case with no crustal fields. We discuss these results and conclude that magnetic cusp regions may be significant sources of ion loss at Mars.

Original languageEnglish
Article numbere2020GL090763
Number of pages11
JournalGeophysical Research Letters
Volume48
Issue number1
DOIs
Publication statusPublished - 16 Jan 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • ambipolar potential
  • ion escape
  • magnetic cusps
  • martian ionosphere
  • particle-in-cell model

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