Observed characteristics of luminous variation events during the initial stage of upward positive leaders
Observed characteristics of luminous variation events during the initial stage of upward positive leaders
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发表时间：
2007
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通讯作者：
Daohong Wang;N. Takagi;Teiji Watanabe
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作者：
Daohong Wang;N. Takagi;Teiji Watanabe
我们测量了从高塔发起的三个向上正先导的初始阶段的相关亚微秒电场和发光变化事件的高速图像。我们发现每个发光变化事件都是由许多电气击穿组成的。我们将发光变化事件分为以下两类：（1）它们以初始主脉冲出现，并且可以从高速图像中识别它们的传播； (2)不存在初始主脉冲并且不能清楚地识别它们的传播。我们推断，在传播方面，发光变化事件类似于 ICC（初始连续电流）脉冲和 M 分量。基于测量结果并作为扩展，我们讨论了M分量的矛盾传播特性，这是多年来文献中一直令人困惑的问题。我们推测：（1）M分量是由许多不同时间、不同地点发生的波组成的，这些波之间可能存在复杂的干扰； (2) M分量可能涉及通过集中或吸收周围电场的电能而在其连续电流通道的任何地方局部激发的一些波； (3) 如果假设 M 分量仅是一个或两个波的过程来进行光学测量，则在大多数情况下，它可能只是一种表观的、人为的（物理上不是真实的）速度，由许多因素产生，例如仪器灵敏度、在哪个通道截面以及如何测量速度。所有这些方面共同解释了 M 分量的矛盾传播特性。
We have measured the correlated sub-microsecond E-fields and high-speed images of the luminous variation events during the initial stage of three upward positive leaders initiated from a high tower. We found that each of the luminous variation events is composed of many electrical breakdowns. We classified the luminous variation events into the following two types: (1) they appear with an initial dominant pulse and their propagations can be identified from high speed images; (2) there is not an initial dominant pulse and their propagations can not be clearly identified. We inferred that in terms of propagation the luminous variation events are similar to ICC (initial continuous current) pulses and M-components. Based on the measured results and as an extension, we have discussed the contradicted propagation characteristics of M-components, an issue which has remained confusing in literatures for many years. We speculated that (1) an M-component is a composition of many waves occurring at different times and different locations, and those waves may interfere each other complicatedly; (2) an M-component may involve some waves excited locally anywhere along its continuous current channel through concentrating or absorbing electrical energy from ambient electric field; (3) the speed of an M-component, if measured optically by assuming that it is a process of only one or two waves , may be , in most of cases, just a kind of apparent and artificial (not real in physics) speed produced by many factors such as instrument sensitivity, and at which channel section and how the speed is measured. All these aspects together account for the contradicted propagation characteristics of M-components.