Monte Carlo simulation of runaway MeV electron breakdown with application to red sprites and terrestrial gamma ray flashes
Monte Carlo simulation of runaway MeV electron breakdown with application to red sprites and terrestrial gamma ray flashes
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失控 MeV 电子击穿的蒙特卡罗模拟及其应用于红色精灵和地面伽马射线闪光
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
U. Inan
中科院分区：
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作者：
N. Lehtinen;T. Bell;U. Inan
在静电场和磁场的存在下，在空气中的均匀相对论逃逸电子击穿的三维蒙特卡罗模型被用来计算电子分布函数，雪崩率，和雪崩传播的方向和速度。我们还导出了在没有磁场的情况下，具有给定动量的电子开始雪崩所需的条件。结果与以前开发的动力学和分析模型以及我们自己的分析估计进行了比较，得出的结论是，许多早期模型中使用的速率[例如，Lehtinen等人，1997年; Taranenko和Mrssel-Dupre，1996年; Yukhimuk等人，1998年; Mrssel-Dupre等人，1998年]被高估了10倍。蒙特卡罗模拟结果被应用到一个流体模型的逃逸电子束在中层大气中的准静电场加速后，一个积极的雷击。特别是，我们考虑的情况下，从横向广泛的（> 100公里）雷暴云的偏远地区的正电荷流失的闪电放电，使用笛卡尔二维模型。由此产生的光发射强度与逃逸电子的红色精灵被发现是可以忽略不计的发射相比，在传统类型的击穿加热的热电子。计算出的伽马射线通量与康普顿伽马射线观测站上的爆发和瞬变源实验探测器观测到的地面伽马射线闪光的量级相同。
A three-dimensional Monte Carlo model of the uniform relativistic runaway electron breakdown in air in the presence of static electric and magnetic fields is used to calculate electron distribution functions, avalanche rates, and the direction and velocity of avalanche propagation. We also derive the conditions required for an electron with a given momentum to start an avalanche in the absence of a magnetic field. The results are compared to previously developed kinetic and analytical models and our own analytical estimates, and it is concluded that the rates used in many early models [e.g., Lehtinen et al., 1997; Taranenko and Roussel-Dupre, 1996; Yukhimuk et al., 1998; Roussel-Dupre et al., 1998] are overestimated by a factor of ∼10. The Monte Carlo simulation results are applied to a fluid model of runaway electron beams in the middle atmosphere accelerated by quasi-electrostatic fields following a positive lightning stroke. In particular, we consider the case of lightning discharges which drain positive charge from remote regions of a laterally extensive (> 100 km) thundercloud, using a Cartesian two-dimensional model. The resulting optical emission intensities in red sprites associated with the runaway electrons are found to be negligible compared to the emissions from thermal electrons heated in the conventional type of breakdown. The calculated gamma ray flux is of the same order as the terrestrial gamma ray flashes observed by the Burst and Transient Source Experiment detector on the Compton Gamma Ray Observatory.