An experimental test of the “transmission‐line model” of electromagnetic radiation from triggered lightning return strokes

Willett, J. C.; Idone, Vincent P.; Orville, Richard E.; Leteinturier, C.; Eybert-Bérard, A.; Barret, L.; Krider, E. Philip

doi:10.1029/jd093id04p03867

Cited by 97 publications

(63 citation statements)

References 16 publications

(10 reference statements)

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“…In this model, the return stroke is represented as a current pulse that propagates from ground to cloud with constant speed and without attenuation. The model has been used successfully in the remote sensing of the currents in lightning return strokes [2]. This model is modified by several scientists by relaxing its simplifying assumptions.…”

Section: Introductionmentioning

confidence: 99%

The Deep Physics Hidden within the Field Expressions of the Radiation Fields of Lightning Return Strokes

Cooray

2016

Atmosphere

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Based on the electromagnetic fields generated by a current pulse propagating from one point in space to another, a scenario that is frequently used to simulate return strokes in lightning flashes, it is shown that there is a deep physical connection between the electromagnetic energy dissipated by the system, the time over which this energy is dissipated and the charge associated with the current. For a given current pulse, the product of the energy dissipated and the time over which this energy is dissipated, defined as action in this paper, depends on the length of the channel, or the path, through which the current pulse is propagating. As the length of the channel varies, the action plotted against the length of the channel exhibits a maximum value. The location of the maximum value depends on the ratio of the length of the channel to the characteristic length of the current pulse. The latter is defined as the product of the duration of the current pulse and the speed of propagation of the current pulse. The magnitude of this maximum depends on the charge associated with the current pulse. The results show that when the charge associated with the current pulse approaches the electronic charge, the value of this maximum reaches a value close to h/8π where h is the Plank constant. From this result, one can deduce that the time-energy uncertainty principle is the reason for the fact that the smallest charge that can be detected from the electromagnetic radiation is equal to the electronic charge. Since any system that generates electromagnetic radiation can be represented by a current pulse propagating from one point in space to another, the result is deemed valid for electromagnetic radiation fields in general.

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Section: Introductionmentioning

confidence: 99%

The Deep Physics Hidden within the Field Expressions of the Radiation Fields of Lightning Return Strokes

Cooray

2016

Atmosphere

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“…However, the original transmission-line formula [Urnan and McLain, 1970, equations (11) and (12)] suggests otherwise because it contains a geometric factor representing the orientation of the channel relative to the observer. Rubinstein and Urnan [1990] reinforce this erroneous impression by discussing only the turn-on term and not the implications to applications of the transmission-line formula itself [e.g., Willett et al, 1988].…”

Section: Introductionmentioning

confidence: 99%

Comment on the transmission‐line model for computing radiation from lightning

Vine

Willett²

1992

J. Geophys. Res.

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The "transmission-line" model is an approximation that is frequently used to relate the electric and magnetic fields radiated during lightning discharges to the currents that produce those fields. A principal prediction of this model is that the distant (radiation) fields are directly proportional to the current propagating along the lightning channel, multiplied by the velocity of propagation. This paper examines the derivation of this relationship and its implications in some detail. We show that the formulas commonly used to describe the transmission-line model cannot be correctly applied to many lightning processes. A correction factor is required that is significant when the channel is not oriented perpendicular to the line of sight to the observer, unless the propagation velocity is only a small fraction of the speed of light. An important implication of this more general version of the model is that the current and velocity decouple so that they could be separately determined by suitable, multistation measurements. INTRODUCTIONIn the "transmission-line" model for lightning discharges it is assumed that the current propagates along the channel at constant velocity and without changing shape. That is, it is assumed that the current advances up the channel as a In particular, the assumption of constant retarded time requires that the channel segment be perpendicular to the line of sight for most of the interesting cases (e.g., where the current waveform has a steep risetime and the propagation 2601

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“…[5,[9][10][11][12][13][14][15]). In this paper, we will use the version of the TL return stroke model recently extended in [16] to include the effect of the elevated strike object.…”

Section: Tl Model For Lightning Return Strokes Extended To Include Anmentioning

confidence: 99%

Determination of lightning currents from far electromagnetic fields: Effect of a strike object

Bermúdez

Rachidi

Janischewskyj

et al. 2007

Journal of Electrostatics

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We discuss in this paper the influence of the presence of an elevated strike object on the peak of the lightning return stroke current determined from remote field measurements. We develop analytical expressions relating the lightning return stroke channel-base current and the far electromagnetic field for different specific cases, namely, (1) ground-initiated return strokes (classical transmission line (TL) model), (2) ground-initiated return strokes including possible reflections at ground level, (3) tall strike objects for which the current's zero-to-peak time is smaller than the travel time along the object, and (4) electrically short strike objects. It is shown that for tall structures, the field enhancement relative to a return stroke initiated at ground level is expressed through a factor equal to k tall ¼ ½1 þ c=vð1 À 2r t Þ=ð1 À r t Þ, where v and c are the return stroke front speed and the speed of light in vacuum, respectively, and r t is the top reflection coefficient. For very short towers and/or very slow return stroke current wavefronts, when the condition t f bh=c applies, expressions relating the far electromagnetic field and the return stroke current were also derived. For case (2), return strokes initiated at ground level, the field enhancement relative to a return stroke initiated at ground level, case (1), is expressed through a factor equal to k short ¼ ð1 þ ðc=vÞr ch2g Þ=ð1 þ r ch2g Þ, where r ch-g represents the reflection coefficient between the lightning channel and the grounding impedance. r

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An experimental test of the “transmission‐line model” of electromagnetic radiation from triggered lightning return strokes

Cited by 97 publications

References 16 publications

The Deep Physics Hidden within the Field Expressions of the Radiation Fields of Lightning Return Strokes

The Deep Physics Hidden within the Field Expressions of the Radiation Fields of Lightning Return Strokes

Comment on the transmission‐line model for computing radiation from lightning

Determination of lightning currents from far electromagnetic fields: Effect of a strike object

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