Lecturer: Qi Zhang (IRF)
Date: 2023-05-31 10:00
Place: Aula

Ion escape from Mars

Qi Zhang
Swedish Institute of Space Physics

Licentiate Examination

When the solar wind reaches the Mars obstacle, mass loading by planetary ions slows down the solar wind and raises the bow shock. The Martian atmosphere is undergoing the a scavenging by the solar wind without the protection of a global magnetic field. Atmospheric escape
is an important process for the evolution of the Martian climate. For present Mars, the dominant escape of atmospheric neutrals is through four channels: Jeans escape, photochemical reactions, sputtering and electron impact ionization. Ions above the exobase get accelerated by the solar wind electric field and can escape.
We here apply a new method for estimating heavy ion (O+, O2+, and CO2+) escape rates at Mars, which combines a hybrid model and observations. We use observed upstream solar wind parameters as input for a hybrid plasma model, where the total ion upflux at the exobase
is a free parameter. We then vary this ion upflux to find the best fit to the observed bow shock location. This method gives us a self-consistent description of the Mars-solar wind interaction, which can be used to study other properties of the solar wind interaction besides escape.

Created 2023-05-10 13:09:47 by Mats Holmström
Last changed 2023-05-12 11:16:41 by Mats Holmström