Laboratory experiments cannot be utilized to justify the action of early streamer emission terminals
Laboratory experiments cannot be utilized to justify the action of early streamer emission terminals
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实验室实验不能用来证明早期流光发射终端的作用
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
V. Cooray
中科院分区：
文献类型：
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作者：
M. Becerra;V. Cooray
在实验室中观察到长气隙在开关脉冲作用下的早期流光发射，以减少先导正向放电的启动时间。这一事实已经被早期流光发射设备的制造商任意外推到在自然闪电条件下启动的向上连接引线的情况，以支持那些声称性能好于富兰克林避雷针的非传统终端。为了讨论这些说法的物理基础和正确性，我们使用了一个基于先导放电物理的自洽模型，在实验室和自然雷电条件下模拟了避雷针的性能。从理论上证明，在开关电压作用下，早期流光的启动确实可以导致实验室长气隙中自蔓延正向引线的早期启动。然而，在向下移动的阶梯形引线产生的电场的影响下，从同一避雷针发起的正连接引线却不是这样。自然条件下正向导流发展的时间演化不同于实验室中的情况，在实验室中，导流起始条件与第一次流光爆发的启动密切相关。我们的研究表明，避雷针在实验室应用的开关电场和下降阶梯形引线产生的电场下的性能之间的相似性是不合理的。因此，使用现有的实验室结果来验证早期流光避雷针在自然条件下的性能是不合理的。
The early emission of streamers in laboratory long air gaps under switching impulses has been observed to reduce the time of initiation of leader positive discharges. This fact has been arbitrarily extrapolated by the manufacturers of early streamer emission devices to the case of upward connecting leaders initiated under natural lightning conditions, in support of those non-conventional terminals that claim to perform better than Franklin lightning rods. In order to discuss the physical basis and validity of these claims, a self-consistent model based on the physics of leader discharges is used to simulate the performance of lightning rods in the laboratory and under natural lightning conditions. It is theoretically shown that the initiation of early streamers can indeed lead to the early initiation of self-propagating positive leaders in laboratory long air gaps under switching voltages. However, this is not the case for positive connecting leaders initiated from the same lightning rod under the influence of the electric field produced by a downward moving stepped leader. The time evolution of the development of positive leaders under natural conditions is different from the case in the laboratory, where the leader inception condition is closely dependent upon the initiation of the first streamer burst. Our study shows that the claimed similarity between the performance of lightning rods under switching electric fields applied in the laboratory and under the electric field produced by a descending stepped leader is not justified. Thus, the use of existing laboratory results to validate the performance of the early streamer lightning rods under natural conditions is not justified.