人工引雷上行正先导传播过程中爆发式磁场脉冲 极性反转现象的观测与分析 Observation and Analysis of Polarity Reversal for the Burst-type Magnetic Pulses during the Propagation of Upward Positive Leader in Rocket-triggered Lightning

文章来源： 发布时间：2018-04-01
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摘 要 为了进一步理解人工引雷上行正先导的传播过程及相关的爆发式电磁辐射脉冲，本文分析了 2014 年 8 月 23 日山东沾化人工触发闪电实验（SHATLE）中获得的三次上行正先导通道含有明显向下传播过程的个例。结 果表明，在初始连续电流阶段观测到的爆发式磁场脉冲极性反转现象与正先导头部发展方向相对于观测位置投影 方向的变化密切相关。因此可以推断，爆发式磁场脉冲是由正先导头部较小空间尺度放电过程辐射出的，就本文 分析的个例而言，爆发式磁场脉冲辐射源的放电尺度约为 2 m，放电强度的最大值达到 2.49 kA。爆发式磁场脉冲 的辐射机制不同于人工引雷先导始发阶段初始脉冲电流产生的磁场脉冲的辐射机制，可能与正先导通道头部的梯 级形式发展过程相关。 关键词 人工引雷 正极性上行先导 初始连续电流 爆发式磁场脉冲 极性反转

Abstract In order to understand the propagating process of upward positive leader and related burst-type electromagnetic pulses, in this paper we analyze three cases of downward propagation of positive leader channels obtained by SHATLE (SHAndong Triggering Lightning Experiment) on August 23, 2014. The results show that the reversals in the polarity of magnetic pulses observed in the stage of initial continuous current are related to the variation of projection direction of positive leader head relative to the observation position. Thereby it can be inferred that the burst-type magnetic pulses are emitted by small spatial scale discharge process of positive leader head. For the cases analyzed in this paper, the discharge scale is about 2 m, and the maximum discharge intensity reaches 2.49 kA. The radiation mechanism for these magnetic pulses is different to the radiation mechanism for the magnetic pulses generated by the initial pulse current in the channel measured at the initial stage of rocket-triggered lightning, which may be related to the stepped propagation of positive leader. Keywords Artificially triggered lightning, Upward positive leader, Initial continuous current, Burst-type magnetic pulses, Polarity reversal
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