Radio frequency emissions from a runaway electron avalanche model compared with intense, transient signals from thunderstorms
Radio frequency emissions from a runaway electron avalanche model compared with intense, transient signals from thunderstorms
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DOI：
10.1029/2004jd005381
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发表时间：
2005-06
影响因子：
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通讯作者：
H. Tierney;R. Roussel-Dupre;E. Symbalisty;W. Beasley
中科院分区：
文献类型：
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作者：
H. Tierney;R. Roussel-Dupre;E. Symbalisty;W. Beasley
[1]提出了雷暴电场中失控电子雪崩的一维模型。以前的模拟已经通过求解修正的相对论Boltzmann方程计算了逃逸电子在不同大气E/p值下的电离率和能量分布函数。我们在流体力学宏观处理中使用随场和压力变化的电离率。这里模拟的失控电子雪崩包括失控电子和低能电子的产生、电场弛豫、电子附着和失控电子损失。模拟的环境电场是由两个电荷盘建立的，电荷密度在正弦空间上变化，峰值幅度为9nC/m~3。这种配置的峰值环境电场在5公里处为538千伏/米。数值计算的射频辐射表现出相对论效应。我们假设失控的电子雪崩是从带电的云层内辐射出的强烈的HF/VHF脉冲的来源。这一案例研究的结果与在窄双极脉冲(NBP)上升部分观测到的高频和甚高频辐射的地面和Forte卫星观测结果进行了比较。在给定的频率和环境下，3-25兆赫、26-48兆赫和60-66兆赫的辐射电场高频和甚高频频谱与有限角度范围内的观测结果是一致的。模拟的时间域峰值辐射电场与nbps的观测平均值相差不到1个标准差。
[1] We present a one-dimensional model of a runaway electron avalanche in a thunderstorm electric field. Previous simulations have calculated the ionization rates and energy distribution functions for runaway electrons, for various atmospheric values of E/p, through the solution of the modified relativistic Boltzmann equation. We use the field- and pressure-dependent ionization rates in a hydrodynamic macroscopic treatment. The runaway electron avalanche modeled here includes the production of runaway and low-energy electrons, electric field relaxation, electron attachment, and runaway electron loss. The model ambient electric field is established from two disks of charge with a sinusoidally spatially varying charge density of 9 nC/m3 peak amplitude. The peak ambient electric field from this configuration is 538 kV/m at 5 km. The numerically calculated radio frequency radiation exhibits relativistic effects. We hypothesize that runaway electron avalanches are sources of intense HF/VHF impulses radiated from within electrified clouds. The results from this case study are compared with ground-based and FORTE satellite observations of HF and VHF radiation observed during the rise portion of narrow bipolar pulses (NBP). Given the specified rates and ambient environment, the radiation electric field HF and VHF spectra covering 3–25, 26–48, and 60–66 MHz are in agreement with observations for limited angular ranges. The modeled peak radiation electric field in the time domain is just below one standard deviation from the observed mean for NBPs.