Abstract
The discharge current of propagating lightning leaders is critical to understand lightning physics and to design lightning protection systems but almost impossible to be measured directly with present-day technology. In this paper, we have investigated the relationship between luminosity and discharge current of propagating positive leaders in laboratory high voltage atmospheric discharges. The continuously propagating positive leader channels were recorded by high-speed video frames. The brightness distribution of the propagating positive leader channel, which was evaluated by the gray value across the central line, obeyed a normal distribution. The mean grayscale pixel value of the propagating positive leader channel central lines obtained in high-speed video frames was compared with the average discharge current measured in the exposure duration of corresponding frames. There is a statistically significant linearity correlation between the discharge current and the channel luminosity of the propagating positive leader. The result further suggests a potential that the discharge current of propagating positive lightning leaders may be obtained based on the optical information observed in the time domain.
Highlights
Lightning is the most impressive and commonly-experienced natural phenomenon
We aimed to investigate the brightness of propagating positive leader channels in meter-scale laboratory high voltage atmospheric discharges using a high-speed camera and to examine the correlation between the light intensity and discharge current measured synchronously
The intense leader channel illuminations were captured by frame j, m, p and s, and the current pulses were measured at t = 54 μs, 67 μs, 79 μs, and 90 μs respectively
Summary
Lightning is the most impressive and commonly-experienced natural phenomenon. The cloud-to-ground (CG) lightning flashes, caused by electric charge imbalance between cloud and ground, are severe threats to the safety of ground facilities, especially for power systems. A CG flash could be comprised of two main components: the initial stage and the return stroke (RS) stage [1]. The downward lightning leaders propagate from the thunder cloud to the ground, as a consequence, upward connecting leaders (UCLs) with opposite polarity initiate from the protruding ground objects, develop in the opposite direction with the downward leaders, eventually meet with the downward leaders. A channel connects the thunder cloud and the ground. In the RS stage, the electric charges with opposite
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