Narrow Bipolar Pulses are generated by bursts of electrical activity in the cloud and these are referred to as Compact Intracloud Discharges (CID) or Narrow Bipolar Events in the current literature. These discharges usually occur in isolation without much electrical activity before or after the event, but sometimes they are observed to initiate lightning flashes. In this paper, we have studied the features of CIDs assuming that they consist of streamer bursts without any conducting channels. A typical CID may contain about 10⁹ streamer heads during the time of its maximum growth. A CID consists of a current front of several nanosecond duration that travels forward with the speed of the streamers. The amplitude of this current front increases initially during the streamer growth and decays subsequently as the streamer burst continues to propagate. Depending on the conductivity of the streamer channels, there could be a low-level current flow behind this current front which transports negative charge towards the streamer origin. The features of the current associated with the CID are very different from those of the radiation field that it generates. The duration of the radiation field of a CID is about 10–20 s, whereas the duration of the propagating current pulse associated with the CID is no more than a few nanoseconds in duration. The peak current of a CID is the result of a multitude of small currents associated with a large number of streamers and, if all the forward moving streamer heads are located on a single horizontal plane, the cumulative current that radiates at its peak value could be about 10⁸ A. On the other hand, the current associated with an individual streamer is no more than a few hundreds of mA. However, if the location of the forward moving streamer heads are spread in a vertical direction, the peak current can be reduced considerably. Moreover, this large current is spread over an area of several tens to several hundreds of square meters. The study shows that the streamer model of the CID could explain the fine structure of the radiation fields present both in the electric field and electric field time derivative.

中文翻译：

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将紧凑型Intracloud流量（CID）建模为流光突发

窄双极脉冲是由云中的电活动爆发产生的，在当前文献中将其称为紧凑云内放电（CID）或窄双极事件。这些放电通常在事件发生之前或之后没有电活动的情况下单独发生，但有时会观察到它们引发闪电。在本文中，我们研究了CID的特征，假设它们由流光脉冲组成，没有任何传导通道。一个典型的CID可能包含大约10 ⁹流光头在其最大的增长时间。CID由几纳秒持续时间的当前前沿组成，该前沿随着拖缆的速度向前传播。该电流前沿的幅度最初在拖缆增长期间增大，并随后随着拖缆突发继续传播而衰减。取决于拖缆通道的电导率，在该电流前沿之后可能会有低电平电流流向拖缆起点传输负电荷。与CID相关的电流的特征与其产生的辐射场的特征非常不同。CID的辐射场的持续时间约为10-20s，而与CID相关的传播电流脉冲的持续时间则不超过几纳秒。^8A。另一方面，与单个拖缆相关的电流不超过几百mA。但是，如果向前移动的拖缆头的位置在垂直方向上扩展，则峰值电流会大大降低。而且，这种大电流散布在几十到几百平方米的面积上。研究表明，CID的流线模型可以解释电场和电场时间导数中存在的辐射场的精细结构。