Laboratory generated symmetrical-waveshape lightning current versus arc channel luminosity

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Identifying a relation between current and channel luminosity is beneficial for producing an approximation to channel current via channel optical signal. In this paper, damped sinusoidal oscillation currents with more or less symmetrical waveshapes are injected into a tungsten copper hemispherical air gap and into a graphite rod air gap. Repeatability and reliability in channel luminosity measurement are compared between two air gap channels. Parametric correlation analyses, involving 12 sequences of lightning currents with a current peak from 13.0 kA to 34.4 kA, a current 10–90% risetime from 9.7 μs to 20.2 μs, and a current half-peak width from 21.6 μs to 46.4 μs, show the luminosity signatures also exhibit more or less symmetrical pulses, although they lag behind the corresponding current pulses. In initial primary pulses of these damped sinusoidal oscillations, the current peak is approximately direct proportional to the luminosity peak. Direct proportional relations are also observed between current 10–90% risetime and luminosity 10–90% risetime, between current half-peak width and luminosity half-peak width, as well as between current charge transfer and luminosity-time integration. These features are similar to those found in classical M-component current pulses associating with the M-component mode of charge transfer. Applicability of the results is further discussed to estimate the channel current from the channel luminosity.