Some Inferences From Radial Electric Fields Measured Inside the Lightning-Channel Corona Sheath

Maslowski, Grzegorz; Rakov, Vladimir A.; Miki, Megumu

doi:10.1109/temc.2011.2109063

Cited by 19 publications

(17 citation statements)

References 12 publications

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“…A lot of numerical models were built to study the characteristics of the lightning channel corona sheath, such as sheath radius, sheath expansion velocity, and corona current (Maslowski & Rakov, 2006;Maslowski et al, 2011;Maslowski & Rakov, 2013;Xu & Chen, 2013;Chan et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

The Spatial Evolution of Upward Positive Stepped Leaders Initiated From a 356‐m‐Tall Tower in Southern China

et al. 2020

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Two initial upward positive leaders (UPLs) in upward negative flashes initiated from a 356‐m‐tall tower were observed with a high‐speed camera, an electric field sensor, and a magnetic field sensor. Although the waveforms of electric fields measured were saturated, both camera images and magnetic fields showed that the two UPLs had obvious stepwise characteristics in their upward moving stage. The magnetic fields associated with the UPLs were characterized by a series of fast‐changing bipolar impulses superimposed on a slowly increasing continuous component as the leaders moved upward, which were well corresponding to the light intensity changes of their high‐speed camera images. The 2‐D step length and step extension speed of the two leaders were estimated in the range of 0.5–3 m and 1.1–9.4 × 105 m/s, respectively. The radius of the leader luminous channel as a function of time and height was also estimated. The channel radius showed first a stable increasing trend in the leader upward moving stage and then 4–5 times of shrinking and expanding processes after the leader connected the cloud. The channel expanding and shrinking speeds were in the range of 2–9 × 104 m/s. Particularly, the channel radius showed an obvious increasing trend with the increase of the height all the time, which was in the range of 2.8–3.5 m when around the tower tip and of 5.6–8.4 m when at 24 m high above the tower tip. Such a feature of the channel radius is in good agreement with the concept of leader corona sheath in literature.

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Section: Introductionmentioning

confidence: 99%

The Spatial Evolution of Upward Positive Stepped Leaders Initiated From a 356‐m‐Tall Tower in Southern China

et al. 2020

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“…Interestingly, the maximum horizontal electric field values during some return strokes were high enough (from 413 kV/m up to more than 520 kV/m) for starting positive breakdown. Time of field relaxation to practically zero level during the overcompensation stage is very similar for all measured waveshapes and is estimated to be approximately 2 ms [23,34]. Hence, one can estimate the decay time constant to be about one-third of this value.…”

Section: Dynamics Of the Corona Sheathmentioning

confidence: 56%

“…Note also that this constant value is assumed to be at the border of the corona sheath which initially expands during the first stage of the return stroke, and then, it shrinks. The radial electric field changes measured at a fixed point of space inside the corona sheath during rocket-and-wire triggered lightning experiments has been discussed in papers [20,23,34].…”

Section: Dynamics Of the Corona Sheathmentioning

confidence: 99%

Corona current concept in lightning return-stroke models of engineering type

Maslowski¹

2010

Archives of Electrical Engineering

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A role of radial corona current in a lightning discharge is discussed in the paper. It is shown that the corona current concept previously introduced by Cooray for lightning return stroke models of distributed-current-source (DCS) type, and later, by Maslowski and Rakov for lumped-current-source (LCS) type models enables to show duality between these two types of models. Further, it is demonstrated that the corona current is useful during consideration of dynamics of the lightning-channel corona sheath. As an example of application of presented approach a relaxation model of charge motion in the corona sheath is analysed together with plots which show the rate of expansion and shrinkage of the lightning corona sheath on both microsecond and millisecond time scales.

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“…Note that, according to Maslowski and Rakov [2006], the conductivity of corona sheath surrounding the lightning channel at the beginning of the return‐stroke stage is a few μ S/m or so. Further, Maslowski et al [2011] estimated the apparent conductivity of return‐stroke corona sheath to be of the order of 10 −8 S/m. It follows from Figure 6 that the influence of corona sheath conductivity on the nearby ground‐level electric field is negligible, so that the corona sheath can be assumed to be perfectly conducting.…”

Section: Modelmentioning

confidence: 99%

Simulation of corona at lightning-triggering wire: Current, charge transfer, and the field-reduction effect

Baba

Rakov

2011

J. Geophys. Res.

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[1] We have examined, using the finite difference time domain (FDTD) method for solving discretized Maxwell's equations, the effect of upward extending wire, used for artificial lightning initiation from natural thunderclouds, and corona space charge emanated from this wire on the close ground-level electric field (prior to lightning initiation). The wire current and charge transfer are also estimated. The lightning-triggering wire is assumed to be perfectly conducting and extending vertically upward with a constant speed of v = 150 m/s. Owing to the limitations of the FDTD method, the wire radius is set to r = 0.27 m, larger than the actual radius (0.1 mm), but the results are not expected to be much influenced by this assumption. The corona space charge that emanated from the wire surface is represented by a conducting cylindrical sheath of outer radius r = 2, 4, 8, and 16 m, coaxial with the wire (the dynamics of corona discharge are not considered here). Other geometries of the corona space charge sheath are considered as well. It has been found that the results presented here are insensitive to the value of corona sheath conductivity ranging from 10 −8 S/m to infinity. The corona space charge layer at the ground is simulated by perfectly conducting cylindrical tubes placed on the ground surface, coaxial with the upward extending conductor. The quasi-static electric field between the thundercloud charge source and the ground is simulated by creating a quasi-uniform, upward directed electric field of 43 kV/m between two parallel conducting plates limiting the FDTD computational domain. The simulated corona space charge at the ground reduced the electric field at the ground surface to 5.5 kV/m, a typical value at the time of rocket launch. The upward directed electric field E z on the ground surface in the vicinity of triggering wire decreases with increasing the altitude of the wire top. When the wire-top altitude is 200 m, the reduction of E z at horizontal distance d = 60 m is about 17, 26, 31, 40, and 52% relative to the background value of 5.5 kV/m for r = 0.27, 2, 4, 8, and 16 m, respectively, while the corresponding reduction of E z at d = 360 m in all cases is only 1% or less. The calculated results for r ≈ 4 to 16 m agree reasonably well with E z variations measured at d = 60 and 350 m from the triggering wire by Biagi et al. (2011). This indicates that the electric field reduction in the vicinity of triggering wire, prior to lightning initiation, is primarily caused by the presence of corona space charge emanated from the wire to a radius of about 4 m or more, as opposed to the presence of wire alone. The total charge transfer from the ground to the wire (whose top is at an altitude of 200 m) is 1.2, 4.5, 6.6, 9.5, and 14 mC for r = 0.27, 2, 4, 8, and 16 m, respectively. The corresponding currents flowing in the wire are 2.1, 7.9, 11, 15, and 22 mA. The model-predicted charges and currents for r = 2 to 4 m are consistent with limited measurements available in the literature, smaller than the values b...

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Some Inferences From Radial Electric Fields Measured Inside the Lightning-Channel Corona Sheath

Cited by 19 publications

References 12 publications

The Spatial Evolution of Upward Positive Stepped Leaders Initiated From a 356‐m‐Tall Tower in Southern China

The Spatial Evolution of Upward Positive Stepped Leaders Initiated From a 356‐m‐Tall Tower in Southern China

Corona current concept in lightning return-stroke models of engineering type

Simulation of corona at lightning-triggering wire: Current, charge transfer, and the field-reduction effect

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