弱电离大气等离子体电子碰撞能量损失的理论研究
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摘要
在前期计算电子能量分布函数的基础上,求出弱电离大气等离子体中各碰撞反应过程的电子能量损失.由于在弹性碰撞中电子-重粒子能量交换很少,同时氮气、氧气分子又有很多能量阈值较低的转动、振动能级存在,因此在大气等离子体中弹性碰撞电子能量损失所占份额很小(直流电场下小于6%).研究发现,弱电离大气等离子体中在不同能量区间占主导的能量损失过程不同.随着有效电子温度(或约化场强)增加,占主导的电子能量损失过程依次为转动激发、振动激发、电子态激发、碰撞电离、加速电离产生的二次电子.在约化场强E/N=1350 Td(或有效电子温度为14 eV)附近,平均电离一个电子所需的能量最小,约为57 eV.因此可以根据不同的需求调节电场强度,从而达到较高的能量利用率.
The energy loss induced by electron collisions in weakly ionized air plasma is calculated based on the electron energy distribution function that we obtained. Since there are a lot of low-energy-threshold molecular rotation and vibration excitations and the electron-molecule energy transfer is inefficient in elastic collision, the fraction of energy loss for electron elastic collision(less than 6%) is negligible. Among different collision processes the electron energy loss is dominant in different energy regions. As the effective electron temperature(or the reduced electric field) increases, the dominant energy loss process becomes sequentially rotational excitation, vibrational excitation, electronic excitation, collisional ionization, and accelerating ionized electrons. When E/N =1350 Td(or Te= 14 eV), the average energy loss per ion-electron pair reaches a minimum value of 57 eV. By controlling the electric field according to the requirement in applications, we can control the electric field to achieve a higher energy efficiency.
The energy loss induced by electron collisions in weakly ionized air plasma is calculated based on the electron energy distribution function that we obtained. Since there are a lot of low-energy-threshold molecular rotation and vibration excitations and the electron-molecule energy transfer is inefficient in elastic collision, the fraction of energy loss for electron elastic collision(less than 6%) is negligible. Among different collision processes the electron energy loss is dominant in different energy regions. As the effective electron temperature(or the reduced electric field) increases, the dominant energy loss process becomes sequentially rotational excitation, vibrational excitation, electronic excitation, collisional ionization, and accelerating ionized electrons. When E/N =1350 Td(or Te= 14 eV), the average energy loss per ion-electron pair reaches a minimum value of 57 eV. By controlling the electric field according to the requirement in applications, we can control the electric field to achieve a higher energy efficiency.
引文
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[26]Phelps A V,Pitchford L C 1985 Phys.Rev.A 31 2932
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[2]Becker K H,Kogelschatz U,Schoenbach K H,Barker R J 2005 NonEquilibrium Air Plasma at Atmosphere Pressure(London:IOP Publishing)
[3]Starikovskaia S M 2006 J.Phys.D:Appl.Phys.39 R265
[4]Siefert N S 2007 Phys.Fluids 19 036102
[5]Kuo S P 2006 Phys.Plasmas 13 033505
[6]Gurevich A V,Borisov N D,Milikh G M 1997 Physics of Microwave Discharges(Amsterdam:Gordon and Breach Science Publishers)
[7]Vidmar R J 1990 IEEE Trans.Plasma Sci.18 733
[8]Gurevich A V,Litvak A G,Vikharev A L,Ivanov O A,Borisov N D,Sergeichev K F 2000 Phys.Uspekhi 43 1103
[9]Macheret S O,Shneider M N,Miles R B 2001 Paper AIAA 2001 2940
[10]Krile J T,Neuber A A,Krompholz H G,Gibson Thomas L 2006 Appl.Phys.Lett.89 201501
[11]Dijk J V,Peerenboom K,Jimenez M,Mihailova D,Mullen J V D 2009J.Phys.D:Appl.Phys.42 194012
[12]Kusher M J 2006 J.Phys.D:Appl.Phys.42 194013
[13]Kim H C,Iza F,Yang S S,Radmilovic-Radjenovic M,Lee J K 2005 J.Phys.D:Appl.Phys.38 R283
[14]Zhou Q H,Dong Z W,Chen J Y 2011 Acta Phys.Sin.60 125202(in Chinese)[周前红,董志伟,陈京元2011物理学报60 125202]
[15]Nam S K,Verboncoeur J P 2008 Appl.Phys.Lett.99 231502
[16]Nam S K,Lim C,Verboncoeur J P 2009 Phys.Plasmas 16 023501
[17]Boeuf J P,Chaudhury B,Zhu G Q 2010 Phys.Rev.Lett.104 015002
[18]Chaudhury B,Boeuf J P,Zhu G Q 2010 Phys.Plasmas 17 123505
[19]Raizer Y P 1991 Gas Discharge Physics(Berlin:Germany:SpringerVerlag)
[20]Macheret S O,Shneider M N,Murray R C 2006 Phys.Plasmas 13023502
[21]Macheret S O,Shneider M N,Murray R C,Miles R B 2005 Paper AIAA 2005 0202
[22]Macheret S O,Shneider M N,Miles R B 2002 AIAA J 40 74
[23]Gudmundsson J T 2005 Univ.Iceland Tech.Rep.RH-09-2005
[24]Gudmundsson J T 2002 Univ.Iceland Tech.Rep.RH-21-2002
[25]Zhou Q H,Dong Z W 2011 Acta Phys.Sin.62 015201(in Chinese)[周前红,董志伟2011物理学报62 125201]
[26]Phelps A V,Pitchford L C 1985 Phys.Rev.A 31 2932
[27]Itikawa Y,Hayashi M,Ichimura A,Onda K,Sakimoto K,Takayanagi K 1986 J.Phys.Chem.Ref.Data 15 985
[28]Itikawa Y 2009 J.Phys.Chem.Ref.Data 38 2689