中国空间科学技术 ›› 2021, Vol. 41 ›› Issue (4): 32-40.doi: 10.16708/j.cnki.1000-758X.2021.0048

• 论文 • 上一篇    下一篇

微等离子体转化二氧化碳发射光谱诊断

孙江宏,孙素蓉,王海兴,马弢   

  1. 1 北京航空航天大学 宇航学院,北京100191
    2 中国航天空气动力技术研究院,北京100074
  • 出版日期:2021-08-25 发布日期:2021-07-30
  • 基金资助:
    国家自然科学基金( 11735004, 11575019, 12005010)

Optical emission spectroscopy diagnostics of CO2 conversion with micro-plasma

SUN Jianghong,SUN Surong,WANG Haixing,MA Tao   

  1. 1 School of Astronautics, Beihang University, Beijing 100191, China
    2 China Academy of Aerospace Aerodynamics, Beijing 100074, China
  • Published:2021-08-25 Online:2021-07-30

摘要: 火星大气层的主要成分为二氧化碳,如果能够利用低温等离子体方法高效分解二氧化碳,使其转化为氧气和一氧化碳加以利用,可以大幅降低航天员生命保障相关载荷长途运输的成本,进一步提高生命保障能力。低温等离子体放电过程中会产生大量活性组分,可以在数百度温度下实现二氧化碳的高效解离,是具有很大潜力的二氧化碳解离与转化方式。设计了一种尺度在亚毫米级、功率输入为数瓦的直流微槽等离子体反应器,可以在较低气体温度下实现二氧化碳分解。测量了反应器电流、功率等放电参数,采用发射光谱确定了体系中激发态组分,分析了激发态粒子谱线强度随输入电压、稀释气体比例等反应器工作参数变化,利用氮气分子振转谱带测量了等离子体放电区振动温度和气体温度。研究表明,添加氩、氦、氮气均可以增强二氧化碳的分解,添加氦气可以促进二氧化碳的电离过程。稀释气体激发态因具有高能量,可以通过潘宁解离通道增强二氧化碳分解。氦组分激发态的能量高于二氧化碳电离能,可以促进二氧化碳的电离反应。微等离子体内存在强烈的振动平动非平衡现象:振动温度约为4400~4800K,而气体温度仅为450 ~600K,表明可以通过合理的放电和结构设计,定向将能量注入到振动态,从而进一步促进二氧化碳的振动解离。

关键词: 二氧化碳分解, 发射光谱, 微等离子体, 原位资源利用, 火星大气

Abstract: The main component of the Martian atmosphere is CO2. If these CO2 can be efficiently converted into O2 and CO by low-temperature plasma for utilization, the launch load cost of life support system can be drastically reduced for deep space mission and the life support capabilities will be further improved. Low-temperature plasma shows a promising potential for CO2 dissociation and conversion. It can produce plenty of reactive species during the discharge, which enables the efficient CO2 conversion at a gas temperature of only a few hundred degrees. A DC microslit plasma reactor on submillimeter scale and with several Watts input power was designed, which can be used for the CO2 conversion at low gas temperature. The discharge parameters, such as discharge current and input power were measured. The optical emission spectroscopy (OES) method was adopted for identification of excited species and their variations with supply voltage and dilution gas content. The plasma vibrational and gas temperatures were measured based on the nitrogen vibrationrotation spectra. It is found that all of the three dilution gases (Ar, He, N2) can enhance the dissociation process, while adding helium gas can improve the CO2 ionization process. The excited species produced by dilution gases promote the CO2 dissociation through Penning dissociation channel because of their high energy. Since the excited state of helium (He*) has an energy higher than CO2 ionization threshold, it leads to an increase of CO2 ionization process. The nonequilibrium feature of microplasma was verified by large deviation between vibrational temperature (4400~4800 K) and gas temperature (450~600 K). Therefore, with reasonable plasma discharge and reactor structure design, the energy can be selectively injected into the vibrational species, which can further increase the CO2 vibrational dissociation.

Key words: CO2 dissociation, optical emission spectroscopy, microplasma, in-situ resource utilization, Martian atmosphere