Study Of Reaction Products And Emission Spectra Of CO₂ Glow Discharge Under Simulated Mars Conditions

Large-scaled dust events such as dust storms and dust devil frequently occur on Mars surface which generate a strong electric field in Mars atmosphere due to frictional static electricity of high-speed dust.The air discharge could take place in Mars atmosphere with low pressure,high conductivity,and a strong electric field.Therefore,the plasma reactions induced by CO2 discharge will have strong effects on the atmospheric compositions and surface materials.Up to now,no direct observational evidence has been reported for the air discharge on Mars surface because of no related in-situ detect equipment on Mars.Laboratory simulation is the only feasible way to achieve Martian environmental conditions on Earth,which establishes a key link between laboratory and Mars exploration.In this work,CO2 glow discharge plasma was generated under simulated Mars conditions.The function work parameters,and reaction products and product yields were investigated in this study.And the emission spectra of CO2 glow discharge were recorded and assigned.The reaction pathway and reaction mechanism of Mars atmosphere discharge were discussed.In this study,we got some conclusions:1)In C02 glow discharge,discharging parameters(frequency,driving voltage,pressure,gap distance),electrode material,type of discharge,discharge gas could affect final product species and yields in different degree;2)These discharge parameters related to the power of discharge which was found to be the primary parameter for the product concentration and ratio of products.The function of yield and power was given;3)By analyzing the O2/CO ratio of CO2 glow discharge and the variation of O2/CO ratio on Mars,we predict that the variation of O2 and CO on Mars related to Mars dust events;4)The excitation lines of C02 plasma were assigned and analyzed systematically.The main plasma reaction paths in C02 glow discharge was discussed.This paper is divided into seven chapters.The front part introduces the Mars exploration history and the basic information of Mars,including data of orbit,terrain characteristics,rocks,minerals features and Mars atmosphere,etc.Chapter 1 introduces the process and mechanism of electric field generation in dust events on Mars.Chapter 2 introduces the structure and energy levels of CO2 vibrational model and its mechanism of CO2 dissociation in plasma.Chapter 3 introduces the experimental instruments used in this study in the simulation environment laboratory and the main experiment process in this study.Chapter 4 introduces the products yields in C02 glow discharge with various parameters and the relative discussion.Chapter 5 introduce the study of CO2 glow discharge emission spectra.In this chapter,the reaction species in CO2 glow discharge were identified and the reaction path was discussed.Chapter 6 is the summary and work outlook.