Influence of Ionization Degrees on Conversion of CO and CO_2 in Atmospheric Plasma near the Ground

A zero-dimensional model is used to study the processes of physical and chemical reactions in atmospheric plasma with different ionization degrees near the ground （0 km）. The temporal evolutions of CO, C02 and other main reactants （namely OH and O2）, which affect the conversion of CO and C02, are obtained for afterglow plasma with different initial values. The results show that the consumption rate of CO is largest when the initiM electron number density neo=1012 cm-3, i.e. the ionization degree is 0.000004%. The number density of CO2 is relatively small when neo=1016 cm-3, i.e. the ionization degree is 0.04%, whereas they are very close under the condition of other ionization degrees. Considering the total number densities of CO and C02 and the consumption rate of CO comprehensively, the best condition is neo=1013 cm-3, i.e. the ionization degree is 0.00004% for reducing the densities of CO and CO2 in the atmospheric plasma. The temporal evolutions of N＋, Ar＋, CO＋ and CO＋ are also shown, and the influences on the temporal evolutions of CO and C02 are analyzed with increasing ionization degree.     

Influence of Ionization Degrees on the Evolutions of Charged Particles in Atmospheric Plasma at Low Altitude

A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude (near 0 km).The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method.The electron lifetimes are obtained for afterglow plasma with different initial values,and the temporal evolutions of the main charged species are presented,which are dominant in reaction processes.The results show that the electron number density decays quickly.The lifetimes of electrons are shortened by about two orders with increasing ionization degree.Electrons then attach to neutral particles and produce negative ions.When the initial electron densities are in the range of 1010～1014cm3,the negative ions have sufficiently high densities and long lifetimes for air purification,disinfection and sterilization.Electrons,O2,O4,CO4 and CO3 are the dominant negative species when the initial electron density ne0≤1013cm3,and only electrons and CO3 are left when ne0≥1015cm3.N+2,N+4 and O+2 are dominant in the positive charges for any ionization degree.Other positive species,such as O+4,N+3,NO+,NO+2,Ar+2 and H3O+ · H2O,are dominant only for a certain ionization degree and in a certain period.     

纳米Si薄膜光学性质和弹性常数的研究

采用基于密度泛函理论的第一性原理的方法,对厚度为0.54～3.30nm纳米Si薄膜的电子结构、光学性质及弹性常数进行了计算。结果表明,纳米Si薄膜是直接带隙半导体材料;随着纳米Si薄膜厚度的减小,带隙逐渐增大;薄膜的光学吸收边发生蓝移,吸收带出现宽化现象;弹性常数、杨氏模量和泊松比呈现尺寸效应。