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A reaction mechanism for vibrationally-cold low-pressure CO2 plasmas
Plasma Sources Science and Technology ( IF 3.3 ) Pub Date : 2020-12-18 , DOI: 10.1088/1361-6595/abc818
A F Silva 1, 2, 3 , A S Morillo-Cands 1 , A Tejero-del-Caz 3, 4 , L L Alves 3 , O Guaitella 2 , V Guerra 3
Affiliation  

The use of plasmas for CO2 utilization has been under investigation in recent years following a wave of environmental awareness. In this work, previously published experimental results on vibrationally cold CO2 plasmas are modelled to define a reaction mechanism, i.e. a set of reactions and rate coefficients validated against benchmark experiments. The model couples self-consistently the electron and heavy particle kinetics. In turn, the simulated results are validated against measurements taken in CO2 DC glow discharges in a relatively large range of experimental conditions: at pressures from 0.4 to 5 Torr, reduced electric fields ranging from 50 to 100 Td and gas flowing from 2 to 8 sccm. The model predicts the measured values of product formation (CO and O) as well as discharge power and electric field. After validation, a thorough analysis of the model’s results is presented, including: electron properties, species densities, power distribution into different excitation channels and main creation and destruction mechanisms of the main species. It is shown that, although vibrational populations are low, they have a significant effect on the electron properties and thus on the electric field and conversion. Moreover, the shape of the EEDF is significantly dependent on the dissociation degree. The role of electronically excited states on CO2 dissociation is also analyzed, showing that the first electronic excited state of CO can have a beneficial or detrimental effect in further producing CO and O in the discharge.



中文翻译:

振动冷的低压CO 2等离子体的反应机理

近年来,随着一波环保意识的发展,正在研究将等离子体用于CO 2的利用。在这项工作中,对先前发布的关于振动冷CO 2等离子体的实验结果进行建模,以定义反应机理,即根据基准实验验证的一组反应和速率系数。该模型自洽地耦合了电子和重粒子动力学。反过来,针对在CO 2中进行的测量验证了仿真结果直流辉光在相对较大的实验条件范围内放电:在0.4至5托的压力下,电场在50至100 Td的范围内减小,气体流动在2至8 sccm的范围内。该模型可以预测产品形成(CO和O)以及放电功率和电场的测量值。验证后,将对模型的结果进行全面分析,包括:电子性质,物质密度,进入不同激发通道的功率分布以及主要物质的主要产生和破坏机制。结果表明,尽管振动种群很低,但它们对电子性能以及电场和转换有显着影响。而且,EEDF的形状明显取决于解离度。电子激发态对一氧化碳的作用还分析了图2的解离,表明CO的第一电子激发态可在放电中进一步产生CO和O方面具有有益或有害的作用。

更新日期:2020-12-18
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