辉石颗粒的辐射带电特性
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摘要
尘埃颗粒带电是月球表面和太阳系空间环境中普遍存在的现象,是理解月球辉光成因、深入认识月球尘埃环境等的重要基础。本文以月壤和宇宙尘中具有代表性的辉石颗粒为对象,在电子枪辐射模拟环境中开展带电实验研究,发现微米大小的颗粒带电量约在105~108e之间,1~5μm的辉石颗粒最容易发生带电运动,产生带电运动颗粒的带电量随着颗粒大小的增大而增大,相近大小的颗粒由于堆积情况不同也存在较大差异。根据辉石颗粒的最大带电量拟合可以得出其最大吸附带电量与颗粒大小成幂指数关系,并与辐射电子能量有关。最后,通过实验数据的拟合,给出了月球辐射环境中尘埃颗粒最大电量模型,并根据实际月球表面情况推测了带电尘埃颗粒的迁移高度特征,发现月面尘埃颗粒的带电运动绝大部分发生在几百米的近月表空间。
The electrification of dust particles is a common phenomenon in the lunar surface and solar system space environment. It is an important basis for understanding the formation of lunar horizon glow and deep understanding the dust environment of lunar surface. In this study,pyroxene particles,which are representative particles in lunar soil and cosmic dust,are chosen to undertake the experiment of electric charge in an electron gun radiation environment.Based on the experimental results,it is found that micron sized pyroxene particles have electric charges of about 105-108 e and the 1-5 microns pyroxene particles are the most susceptible to electric motion. The electric quantity of charged pyroxene particles increases with the increase of particle size. There are also dramatic differences between particles of similar size due to different accumulation conditions. According to the maximum power fitting of pyroxene granule,it can be concluded that According to the maximum charged electric quantity fitting of pyroxene particles,it can be concluded that its maximum adsorption capacity is exponentially related to the size of particles,and is also related to the radiation electron energy. Finally,the maximum power model of dust particles in the lunar radiation environment is given by. According to the actual lunar surface conditions,the migration height of charged dust particles is predicted,and the most part of the charged movement of dust particles in lunar surface occurs in a few hundred meters. The results provide a reference for further understanding the electrostatic migration and dustenvironment of the lunar surface dust. A maximum charged power model of dust particles in lunar radiation environment is finally proposed by fitting the experimental data. According to the actual lunar surface conditions,the migration height of the charged dust particles is predicted,and the most part of the charged movement of dust particles in lunar surface occurs in several hundred meters. The results provide a reference for further understanding the electrostatic migration and dust environment of the lunar dust.
The electrification of dust particles is a common phenomenon in the lunar surface and solar system space environment. It is an important basis for understanding the formation of lunar horizon glow and deep understanding the dust environment of lunar surface. In this study,pyroxene particles,which are representative particles in lunar soil and cosmic dust,are chosen to undertake the experiment of electric charge in an electron gun radiation environment.Based on the experimental results,it is found that micron sized pyroxene particles have electric charges of about 105-108 e and the 1-5 microns pyroxene particles are the most susceptible to electric motion. The electric quantity of charged pyroxene particles increases with the increase of particle size. There are also dramatic differences between particles of similar size due to different accumulation conditions. According to the maximum power fitting of pyroxene granule,it can be concluded that According to the maximum charged electric quantity fitting of pyroxene particles,it can be concluded that its maximum adsorption capacity is exponentially related to the size of particles,and is also related to the radiation electron energy. Finally,the maximum power model of dust particles in the lunar radiation environment is given by. According to the actual lunar surface conditions,the migration height of charged dust particles is predicted,and the most part of the charged movement of dust particles in lunar surface occurs in a few hundred meters. The results provide a reference for further understanding the electrostatic migration and dustenvironment of the lunar surface dust. A maximum charged power model of dust particles in lunar radiation environment is finally proposed by fitting the experimental data. According to the actual lunar surface conditions,the migration height of the charged dust particles is predicted,and the most part of the charged movement of dust particles in lunar surface occurs in several hundred meters. The results provide a reference for further understanding the electrostatic migration and dust environment of the lunar dust.
引文
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[2]Rennilson J J,Criswell D R.Surveyor observations of lunar horizon-glow[J].The Moon,1974,10(2):121-142.
[3]Stubbs T J,Vondrak R R,Farrell W M.A dynamic fountain model for lunar dust[J].Advances in Space Research,2006,37(1):59-66.
[4]Mc Coy J E,Criswell D R.Evidence for a high altitude distribution of lunar dust[M].New York:Pergamon Press,1974:2991-3005.
[5]Elssser H,Fechtig H.Interplanetary dust and zodiacal light[M].New York:Springer,1976.
[6]Zook H A,Mc Coy J E.Large scale lunar horizon glow and a high altitude lunar dust exosphere[J].Geophysical Research Letters,1991,18(11):2117-2120.
[7]Berg O E,Richardson F F,Burton H.Lunar ejecta and meteorites experiment[M].Washington D C:NASA,1973,SP-330.
[8]Halekas J S,Delory G T,Lin R P,et al.Lunar prospector observations of the electrostatic potential of the lunar surface and its response to incident currents[J].Journal of Geophysical Research:Space Physics,2008,113(A9):A09102.
[9]Grün E,Horanyi M,Sternovsky Z.The lunar dust environment[J].Planetary and Space Science,2011,59(14):1672-1680.
[10]Mateo-Velez J C,Sarrailh P,Hess S,et al.Lunar dust migration by electrostatic charging:numerical modelling[M].Texas:LPI,2015:1792.
[11]Grossman J J,Ryan J A,Mukherjee N R,et al.Microchemical,microphysical and adhesive properties of lunar material[M].New York:Pergamon Press,1970:2171.
[12]Gaier J R,Berkebile S P.Implications of adhesion studies for dust mitigation on thermal control surfaces[J].New European Union,2013,51(1):55-57.
[13]Mendis D A,Rosenberg M.Cosmic dusty plasmas[J].Annual Review of Astronomy and Astrophysics,1994,32:419-463.
[14]Kimura H,Mann I.The electric charging of interstellar dust in the solar system and consequences for its dynamics[J].The Astrophysical Journal,1998,499(1):454-462.
[15]Ma Q Y,Matthews L S,Land V,et al.Charging of aggregate grains in astrophysical environments[J].The Astrophysical Journal,2013,763(2):77-85.
[16]Borisov N D,Zakharov A V.Electrostatic charging and motion of dust near the surface of an asteroid[J].Solar System Research,2014,48(1):22-32.
[17]Mitchell C J,Horányi M,Haves O,et al.Saturn’s spokes:lost and found[J].Science,2006,311(5767):1587-1589.
[18]Abbas M M,Tankosic D,Craven P D,et al.Lunar dust grain charging by electron impact:complex role of secondary electron emissions in space environments[J].The Astrophysical Journal,2010,718(2):795-809.
[19]Němecˇek Z,Pavlu°J,afránkováJ,et al.Lunar dust grain charging by electron impact:dependence of the surface potential on the grain size[J].The Astrophysical Journal,2011,738(1):14.
[20]Heiken G,Vaniman D,French B M.Lunar sourcebook–a user’s guide to the moon[M].Cambridge:Cambridge University Press,1991.
[21]Brownlee D E.Cosmic dust:building blocks of planets falling from the sky[J].Elements,2016,12(3):165-170.
[22]Flynn G J,Nittler L R,Engrand C.Composition of cosmic dust:sources and implications for the early solar system[J].Elements,2016,12(3):177-183.
[23]Jaeger C,Mutschke H,Begemann B,et al.Steps toward interstellar silicate mineralogy.1:laboratory results of a silicate glass of mean cosmic composition[J].Astronomy and Astrophysics,1994,292:641-655.
[24]Johnson S W,Taylor G J,Wetzel J P.Environmental effects on lunar astronomical observatories[M].Houston:Johnson Space Center,1992:329-335.
[25]Liu Y,Taylor L A.Characterization of lunar dust and a synopsis of available lunar simulants[J].Planetary and Space Science,2011,59(14):1769-1783.
[26]Sharma J,Gahlot A,Sharma S C,et al.Effect of dust charge fluctuations on upper hybrid wave instabilities in magnetized dusty plasma[M].New Delhi:Jawaharlal Nehru University,2014:1460350.
[27]沈熊,魏乃龙,彭涛.应用激光相位—多普勒系统测量雾化液滴颗粒和流动特性[J].流体力学实验与测量,2000,14(2):54-60.
[28]Horányi M,Walch B,Robertson S,et al.Electrostatic charging properties of Apollo 17 lunar dust[J].Journal of Geophysical Research,1998,103(E4):8575-8580.
[29]Halekas J S,Lin R P,Mitchell D L.Large negative lunar surface potentials in sunlight and shadow[J].Geophysical Research Letters,2005,32(9):L09102.
[30]丁锋,万卫星.月球电离层探测与研究[J].地球化学,2010,39(1):11-14.
[31]Freeman J W,Ibrahim M.Lunar electric fields,surface potential and associated plasma sheaths[J].The Moon,1975,14(1):103-114.
[32]Halekas J S,Delory G T,Lin R P,et al.Lunar prospector observations of the electrostatic potential of the lunar surface and its response to incident currents[J].Journal of Geophysical Research:Space Physics,2008,113(A9):A09102.
[33]Horányi M,Szalay J R,Kempf S,et al.A permanent,asymmetric dust cloud around the Moon[J].Nature,2015,522(7556):324-326.