MC法模拟相对论逃逸电子雪崩理论机制
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摘要
基于GEANT4软件完成闪电高能辐射RREA机制的模拟计算。采用有理数逼近的拟合方法,得到的雪崩距离常数、雪崩时间常数、光子数与逃逸电子数比值的计算公式,均为只有电场强度一个变量的函数,便于各个参数的理论计算和对比分析;评估了GEANT4中不同物理模型对仿真计算结果的影响,结果表明:构造函数EM Opt4采用的物理模型精度最高,输运相等的雪崩距,产生的轫致辐射光子最多,但计算过程耗费的时间也最长。
Based on GEANT4 software,the parameters of lightning energetic radiation RREA mechanism were calculated. Using the fitting method of rational approximation,the formulas for calculating avalanche growth length,avalanche growth time,the ration of bremsstrahlung photons to energetic electrons were obtained. These formulas are functions that contain only one variable of electric field strength,which facilitate the calculation and comparative analysis of each parameter. The impacts of different physical models in GEANT4 on the simulation results were evaluated. The calculation results show that the constructor function EM Opt4 adopts the highest accuracy,produces the most bremsstrahlung photons,but the calculation process takes the longest time.
Based on GEANT4 software,the parameters of lightning energetic radiation RREA mechanism were calculated. Using the fitting method of rational approximation,the formulas for calculating avalanche growth length,avalanche growth time,the ration of bremsstrahlung photons to energetic electrons were obtained. These formulas are functions that contain only one variable of electric field strength,which facilitate the calculation and comparative analysis of each parameter. The impacts of different physical models in GEANT4 on the simulation results were evaluated. The calculation results show that the constructor function EM Opt4 adopts the highest accuracy,produces the most bremsstrahlung photons,but the calculation process takes the longest time.
引文
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[9]Gurevich A V,Duncan L M,Karashtin A N,et al.Radio emission of lightning initiation[J]. Physics Letters A,2003,312(3! 4):228-237.
[10]Gurevich A V,Medvedev Y V,Zybin K P. Thermal electrons and electric current generated by runaway breakdown effect[J]. Physics Letters A,2004,321(3):179-184.
[11]Gurevich A V,Medvedev Y V,Zybin K P. New type discharge generated in thunderclouds by joint action of runaway breakdown and extensive atmospheric shower[J]. Physics Letters A,2004,329(4-5):348-361.
[12]Gurevich A V, Zybin K P, Medvedev Y V.Amplification and nonlinear modification of runaway breakdown[J]. Physics Letters A,2006,349(5):331-339.
[13]Gurevich A V,Zybin K P,Medvedev Y V. Runaway breakdown in strong electric field as a source of terrestrial gamma flashes and gamma bursts in lightning leader steps[J]. Physics Letters A,2007,361(1-2):119-125.
[14] Lehtinen N G,Bell T F,Inan U S. Monte Carlo simulation of runaway MeV electron breakdown with application to red sprites and terrestrial gamma ray flashes[J]. Journal of Geophysical Research,1999,A11(104):24699-24712.
[15]Dwyer J R. A fundamental limit on electric fields in air[J]. Geophysical Research Letters,2003,30(20):1-8.
[16]International Commission on Radiation Units and Measurements. Stopping Powers for Electrons and Positrons[R].ICRU REPORT 37. 1984:70-73.
[17]Skeltved A B,stgaard,Nikolai,Carlson B,et al.Modeling the relativistic runaway electron avalanche and the feedback mechanism with GEANT4[J].Journal of Geophysical Research Space Physics,2014,119(11):9174-9191.
[18]Coleman L M,Dwyer J R. Propagation speed of runaway electron avalanches[J]. Geophysical Research Letters,2006,33(33):156-185.
[2]Gurevich A V,Milikh G M,Roussel-Dupre R.Runaway electron mechanism of air breakdown and preconditioning during a thunderstorm[J]. Physics Letters A,1992,165(5! 6):463-468.
[3]Roussel-DupréRA,Gurevich AV,Tunnell T,et al.Kinetic theory of runaway air-breakdown[J].Physical Review E Statistical Physics Plasmas Fluids&Related Interdisciplinary Topics,1993,49(49):2257-2271.
[4]Fishman G J,Bhat P N,Mallozzi R,et al. Discovery of intense gamma-ray flashes of atmospheric origin[J]. Science,1994,264(5163):1313-1316.
[5]Smith D M, Barrington-Leigh C P. Terrestrial gamma-ray flashes observed up to 20 MeV[J].Science,2005,307(5712):1085-1088.
[6] Briggs M S,Fishman G J,Connaughton V,et al.First results on terrestrial gamma ray flashes from the Fermi Gamma-ray Burst Monitor[J]. Journal of Geophysical Research Space Physics, 2010, 115(A7):387-410.
[7]Marisaldi M,Fuschino F,Labanti C,et al. Detection of terrestrial gamma ray flashes up to 40 MeV by the AGILE satellite[J]. Journal of Geophysical Research Atmospheres,2010,115(A00E13):1-12.
[8]Marisaldi M,Argan A,Trois A,et al. Gamma-ray localization of terrestrial gamma-ray flashes[J].Physical Review Letters,2010,105(12):1-12.
[9]Gurevich A V,Duncan L M,Karashtin A N,et al.Radio emission of lightning initiation[J]. Physics Letters A,2003,312(3! 4):228-237.
[10]Gurevich A V,Medvedev Y V,Zybin K P. Thermal electrons and electric current generated by runaway breakdown effect[J]. Physics Letters A,2004,321(3):179-184.
[11]Gurevich A V,Medvedev Y V,Zybin K P. New type discharge generated in thunderclouds by joint action of runaway breakdown and extensive atmospheric shower[J]. Physics Letters A,2004,329(4-5):348-361.
[12]Gurevich A V, Zybin K P, Medvedev Y V.Amplification and nonlinear modification of runaway breakdown[J]. Physics Letters A,2006,349(5):331-339.
[13]Gurevich A V,Zybin K P,Medvedev Y V. Runaway breakdown in strong electric field as a source of terrestrial gamma flashes and gamma bursts in lightning leader steps[J]. Physics Letters A,2007,361(1-2):119-125.
[14] Lehtinen N G,Bell T F,Inan U S. Monte Carlo simulation of runaway MeV electron breakdown with application to red sprites and terrestrial gamma ray flashes[J]. Journal of Geophysical Research,1999,A11(104):24699-24712.
[15]Dwyer J R. A fundamental limit on electric fields in air[J]. Geophysical Research Letters,2003,30(20):1-8.
[16]International Commission on Radiation Units and Measurements. Stopping Powers for Electrons and Positrons[R].ICRU REPORT 37. 1984:70-73.
[17]Skeltved A B,stgaard,Nikolai,Carlson B,et al.Modeling the relativistic runaway electron avalanche and the feedback mechanism with GEANT4[J].Journal of Geophysical Research Space Physics,2014,119(11):9174-9191.
[18]Coleman L M,Dwyer J R. Propagation speed of runaway electron avalanches[J]. Geophysical Research Letters,2006,33(33):156-185.