Kinetic Calculations of the Charge Exchange Efficiency for Solar Wind Protons in the Extended Martian Hydrogen Corona

Abstract

Model calculations of the charge exchange efficiency for solar wind protons colliding with hydrogen atoms of the extensive Martian corona are presented. It is shown that the energy spectrum of hydrogen atoms penetrating in the Martian atmosphere is identical to the spectrum of protons of the unperturbed solar wind. The charge exchange efficiency varies from 2 to 4% depending on the boundary location of the Martian induced magnetosphere. The presented calculations, combined with the kinetic model of proton precipitation proposed earlier, enable us to follow all proton penetration stages of the unperturbed solar wind into denser atmospheric layers and to estimate the characteristics of proton aurorae observed on the Mars.

Evidence of Non‐Thermal Hydrogen in the Exosphere of Mars Resulting in Enhanced Water Loss

“…A separate study dedicated toward understanding the production of hot H from collisions between thermal H and non‐thermal O also predicted small ratios of energetic to thermal H densities (Shematovich, 2013), thereby disfavoring this mechanism as well. By contrast, the efficiency of the solar wind charge exchange process with exospheric thermal H and the resulting non‐thermal H atoms created via secondary collisions (Bisikalo et al., 2018; Shematovich, 2013, 2021; Shematovich & Bisikalo, 2020, 2021) does appear to provide the needed number of hot atoms to explain the HST observations (exobase density ratio of hot to cold ∼10 −3 ). Hence, for this study, we have focused on the third mechanism, the creation of non‐thermal H through charge exchange with solar wind protons at Mars.…”

“…The non-thermal H density distribution at Mars is determined through 1D Monte Carlo (MC) modeling (Bisikalo et al, 2018;Shematovich, 2013Shematovich, , 2021Shematovich & Bisikalo, 2020, 2021. The 1D model does not incorporate the increase in the volume of each voxel with altitude appropriate for spherical geometry, which may overestimate the number of non-thermal atoms by a factor (r/R Mars ) 2 .…”