Determination of reflection coefficients at the top and bottom of elevated strike objects struck by lightning

Bermúdez, José Luis; Rubinstein, Marcos; Rachidi, Farhad; Heidler, F.; Paolone, Mario

doi:10.1029/2002jd002973

Cited by 46 publications

(31 citation statements)

References 13 publications

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“…For the typical RT (5h/c), we can derive the fitted coefficient B for different tall heights from the computed field values as shown below Also, we found that the reflection coefficients of tall objects ranging from observed data presented by Bermudez et al (2003) have not much effect on the far magnetic field, as shown in Fig. 8, and our fitted functions from Eqs.…”

Section: For the Finitely Conducting Groundmentioning

confidence: 94%

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Validation and revision of far-field-current relationship for the lightning strike to electrically short objects

Zhang

Hou

et al. 2014

Journal of Atmospheric and Solar-Terrestrial Physics

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Section: For the Finitely Conducting Groundmentioning

confidence: 94%

“…They are characterized by the same peak value (12 kA), but with different RTs, namely 3h/c and 5h/c. The reflection coefficients are assumed to be constant and equal to ρ t ¼ À0.5 at the top of objects and ρ b ¼ 1 at the bottom of objects, respectively, as shown in Bermudez et al (2003).…”

Section: The Model Introductionmentioning

confidence: 99%

Validation and revision of far-field-current relationship for the lightning strike to electrically short objects

Zhang

Hou

et al. 2014

Journal of Atmospheric and Solar-Terrestrial Physics

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“…On the other hand, Baba and Rakov [7] have pointed out that the characteristic impedance of a vertical cylinder above ground varies with height, which implies that pulses propagating along such a cylinder in general cannot preserve their amplitude and shape. Bermudez et al [21] stated that the controversy regarding the validity of uniform transmission line representation for a vertical conductor above ground "is not settled yet." One of the reasons for the contradictory views found in the literature is the lack of understanding of the mechanism of attenuation of current waves propagating along a perfectly conducting wire.…”

Section: Introductionmentioning

confidence: 99%

On the Mechanism of Attenuation of Current Waves Propagating Along a Vertical Perfectly Conducting Wire Above Ground: Application to Lightning

Baba

Rakov

2005

IEEE Trans. Electromagn. Compat.

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Abstract-It is known from both theory and numerical simulations that a current pulse suffers apparent attenuation as it propagates along a vertical perfect conductor of uniform, nonzero thickness (e.g., a cylinder) above perfectly conducting ground, excited at its bottom by a lumped source. The associated electromagnetic field structure is non-transverse electromagnetic (TEM), particularly near the source region. On the other hand, it has been shown analytically by Thottappillil et al. (2001Thottappillil et al. ( , 2004 that no attenuation occurs and the electromagnetic field structure is pure transverse electromagnetic (TEM) if the conductor thickness and source size are assumed to be infinitesimal. The goal of this paper is to examine the mechanism of current attenuation as it propagates along a nonzero thickness conductor, based on the scattering theory and on a nonuniform transmission line approximation. In applying the scattering theory, we decompose the "total" current in the conductor into two components that we refer to as the "incident" and "scattered" currents. The "incident" current serves as a reference (no attenuation), specified disregarding the interaction of resultant electric and magnetic fields with the conductor, while the "scattered" current, found here using the finite-difference time-domain (FDTD) method, can be viewed as a correction to account for that interaction. The scattered current modifies the incident current so that the resultant total current pulse appears attenuated. Thus, the current attenuation is likely to be due to field scattering that does not occur in the case of zero thickness conductor. The attenuation of the total current pulse is accompanied by the lengthening of its tail, such that the total charge transfer is independent of height. Approximation of the vertical conductor above ground by a nonuniform transmission line whose characteristic impedance increases with increasing height is shown to reasonably reproduce the current pulse attenuation predicted by the scattering theory. In this approximation, the apparent current attenuation with height can be attributed to waves reflected back to the source. The results have important implications for development and interpretation of lightning models.

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“…The analysis was based on engineering models [3][4][5][6][7][8], distributed circuit models [9] and electromagnetic models [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Interaction of Secondary Current Pulses with the Main Wavefront

Raysaha¹,

Kumar²

2011

JLR

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Additional current pulses get injected into the lightning channel from branches and/or from successive reflections within struck Tall Grounded Objects (TGOs). These pulses termed here as "secondary current waves/pulses" affect the lightning Electro-Magnetic Fields (EMFs). With regard to these, an important question arises on whether or not these pulses get reflected at the main wavefront and there seems to be uncertainty in the pertinent literature. A particular case involving only the first ground end reflection from a struck TGO has been fully dealt in our earlier work. However, the same for subsequent reflections from TGO and that for the current fed by the branches were not dealt and this forms the main goal of present work. As the main objective is to ascertain the status of these secondary current pulses after they have reached the main wavefront, dynamics at the point of injection assumes lesser importance. In view of this, a lumped voltage source is employed for the injection of secondary current pulses at appropriate time instants. The main stroke evolution is emulated by a macroscopic physical model, which was developed in our earlier work. Investigation showed that these secondary pulses merge with the main wavefront without any sign of reflection whatsoever. Analysis showed that the spatial dynamic resistance/conductance profile at the main wavefront is basically responsible for the same with distributed source providing additional support. These findings are in line with the observations made in our earlier work for the first ground end reflected current.

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Determination of reflection coefficients at the top and bottom of elevated strike objects struck by lightning

Cited by 46 publications

References 13 publications

Validation and revision of far-field-current relationship for the lightning strike to electrically short objects

Validation and revision of far-field-current relationship for the lightning strike to electrically short objects

On the Mechanism of Attenuation of Current Waves Propagating Along a Vertical Perfectly Conducting Wire Above Ground: Application to Lightning

Investigation on the Interaction of Secondary Current Pulses with the Main Wavefront

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