Electron cooling by carbon monoxide in the atmospheres of Mars and Venus

TL;DR

This paper calculates electron cooling rates for CO in Martian and Venusian atmospheres, revealing that CO cooling surpasses CO2 at certain altitudes and examining the impact of cross section measurements.

Contribution

It provides the first detailed comparison of electron cooling by CO versus CO2 in planetary atmospheres, highlighting the significance of CO at specific altitudes.

Findings

CO cooling becomes dominant above 300 km on Mars

CO cooling surpasses CO2 cooling above 168 km on Venus

Cooling rates are sensitive to vibrational excitation cross section measurements

Abstract

Electron cooling, in which free electrons lose energy to vibrational excitation of gases, has been identified as a significant process in the atmospheres of Mars and Venus for electron impact on CO2. This process does not appear to have been evaluated for CO, although the density of CO exceeds that of CO2 in the upper atmospheres of these planets. In this paper electron cooling rates for CO are calculated and compared with existing rates for CO2. It is found that electron cooling by CO becomes more significant than by CO2 above altitudes of about 300 km on Mars and about 168 km on Venus. The sensitivity of the calculated cooling rates to different measurements of the integral cross sections for electron-impact vibrational excitation of CO is also investigated. PACS Codes: 34.80.Gs, 96.12.Jt