Geometrical and physical parameters affecting distant electric fields radiated by lightning return strokes (original) (raw)
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The electromagnetic field of an improved lightning return-stroke representation
IEEE Transactions on Electromagnetic Compatibility, 1993
An analytical technique for correlating ground level return-stroke currents to the produced surface electromagnetic fields is dihussed. The ground is realistically assumed with finite conductivity. The lossless nonuniform transmission b e model with exponentially decreasing cross section upwards, turns out to be a powerful, as well as plausible, discharge channel representation. By virtue of the analytical fashion of this approach, a number of details typically ascribed M the electromagnetic performances of a lightning appear on the whole suitably accounted for. Therefore, the employed work hypotheses and the results found by this investigation a priori performed for EMC studies, can be assumed as useful remarks for a better outline of the discharge phenomenon.
Electric field intensity of the lightning return stroke
Journal of Geophysical Research, 1973
Institute o] Atmospheric Physics, University o] Arizona, Tucson, Arizona 857•1 From an examination of about 1000 electric field wave forms produced by lightning return strokes in 16 storms at distances between 20 and 100 km from an observation site at the Kennedy Space Center, Florida, a typical return stroke current wave form is derived. For this current wave form, the electric field intensity at distances between 0.5 and 100 km is computed for three values of return stroke velocity. The resultant curves for close lightning • Now at
Progress In Electromagnetics Research B
In this paper the results of the estimated electric field associated with tortuous lightning paths at close distance (50 m to 500 m) are shown. Such results are compared with experimental data available in the literature and are illustrated along with a quantitative analysis of the field waveforms and their frequency spectra. The limits of the usual straight-vertical channel assumption and the influence of tortuosity at different azimuth and distances from the lightning channel base are also highlighted.
Electromagnetic models of the lightning return stroke
Journal of Geophysical Research, 2007
1] Lightning return-stroke models are needed for specifying the source in studying the production of transient optical emission (elves) in the lower ionosphere, the energetic radiation from lightning, and characterization of the Earth's electromagnetic environment, as well as studying lightning interaction with various objects and systems. Reviewed here are models based on Maxwell's equations and referred to as electromagnetic models. These models are relatively new and most rigorous of all models suitable for computing lightning electromagnetic fields. Maxwell's equations are numerically solved to yield the distribution of current along the lightning channel. Different numerical techniques, including the method of moments (MoM) and the finite difference time domain (FDTD) method, are employed. In order to achieve a desirable current-wave propagation speed (lower than the speed of light in air), the channel-representing wire is embedded in a dielectric (other than air) or loaded by additional distributed series inductance. Capacitive loading has been also suggested. The artificial dielectric medium is used only for finding the distribution of current along the lightning channel, after which the channel is allowed to radiate in air. Resistive loading is used to control current attenuation with height. In contrast with distributed circuit and so-called engineering models, electromagnetic return-stroke models allow a self-consistent full-wave solution for both lightning-current distribution and resultant electromagnetic fields. In this review, we discuss advantages and disadvantages of four return-stroke channel representations: a perfectly conducting/resistive wire in air, a wire embedded in a dielectric (other than air), a wire in air loaded by additional distributed series inductance, and a wire in air having additional distributed shunt capacitance. Further, we describe and compare different methods of excitation used in electromagnetic return-stroke models: closing a charged vertical wire at its bottom with a specified grounded circuit, a delta-gap electric field source, and a lumped current source. Finally, we review and compare representative numerical techniques used in electromagnetic modeling of the lightning return stroke: MoMs in the time and frequency domains and the FDTD method. We additionally consider the so-called hybrid model of the lightning return stroke that employs a combination of electromagnetic and circuit theories and compare this model to electromagnetic models. Citation: Baba, Y., and V. A. Rakov (2007), Electromagnetic models of the lightning return stroke,
Evaluation of Lightning Return Stroke Current Using Measured Electromagnetic Fields
2012
Abstract: The lightning return stroke current is an important parameter for considering the effect of lightning on power lines. In this study, a numerical method is proposed to evaluate the return stroke current based on measured electromagnetic fields at an observation point in the time domain. The proposed method considers all field components and the full wave shape of the current without the use of a special current model as a basic assumption compared to previous methods.
Reproduction of Lightning Electromagnetic Field Waveforms by Engineering Model of Return Stroke
IEEE Transactions on Electromagnetic Compatibility, 2004
In this short paper, a new "engineering" model of subsequent return stroke has been proposed. In the model, the propagation characteristic of a channel current follows the Diendorfer and Uman (DU) model in the bottom region but a current pulse attenuates further in the upper region. This model has succeeded in reproducing all the features of reported typical electric-and magnetic-field waveforms associated with natural subsequent lightning and triggered lightning.
CHARACTERIZATION OF LIGHTNING ELECTROMAGNETIC FIELDS AND THEIR MODELING
Characteristics of measured electric and magnetic fields generated by leaders and return strokes in lightning cloud-to-ground discharges are reviewed. The very close (within tens to hundreds of meters) lightning electromagnetic environment is discussed. Typical field waveforms at distances ranging from 10 m to 200 km are shown. Modeling of lightning return strokes as sources of electromagnetic fields is reviewed. Four classes of models, defined on the basis of the type of governing equations, are considered. These four classes are: 1) gas-dynamic models, 2) electromagnetic models, 3) distributed-circuit models, and 4) engineering models. Model-predicted fields are compared with measurements.
American Journal of Applied Sciences, 2007
In this study we present and analysis of the return-stroke lightning current and described their models which existing in the literature by several authors for the evaluation of radiated electromagnetic fields and modelling the coupling with electrical systems based on the calculation of induced voltages. the objective of this work is to take part in the improvement of the coordination of electric insulations and to put device also for calculation of the over-voltages induced in the electrical networks by the indirect lightning strokes which represent the most dangerous constraint and most frequent. A comparative study between the existing models and the analysis of the parameters which affect the space and temporal behaviour of the current lightning strokes as well as the importance of the lightning current at the channel base form the essential consequence of this study.
A Novel Interpretation of the Electromagnetic Fields of Lightning Return Strokes
Atmosphere
Electric and/or magnetic fields are generated by stationary charges, uniformly moving charges and accelerating charges. These field components are described in the literature as static fields, velocity fields (or generalized Coulomb field) and radiation fields (or acceleration fields), respectively. In the literature, the electromagnetic fields generated by lightning return strokes are presented using the field components associated with short dipoles, and in this description the one–to-one association of the electromagnetic field terms with the physical process that gives rise to them is lost. In this paper, we have derived expressions for the electromagnetic fields using field equations associated with accelerating (and moving) charges and separated the resulting fields into static, velocity and radiation fields. The results illustrate how the radiation fields emanating from the lightning channel give rise to field terms varying as and , the velocity fields generating field terms ...
Journal of Geophysical Research: Atmospheres, 2008
1] In this paper, the developed formulation, which we shall call the ''reference'' one, is used to assess the validity of the most popular simplified approach for the calculation of the lightning electromagnetic field over a conducting earth, namely, the Cooray-Rubinstein (CR) approximation. This formula provides a simple method to evaluate the radial component of the electric field which is the component most affected by the finite ground conductivity and which plays an important role within the Agrawal et al. (1980) field-to-transmission line-coupling model. Several configurations are examined, with different values for the ground conductivity and different field observation points. A thorough analysis of all the simulated field components is carried out and comparisons are also made with the ''ideal'' field, namely, the field that would be present under the assumption of perfectly conducting ground. It is shown that for channel base current typical of subsequent strokes and for very low conductivities, the CR formula exhibits some deviations from the reference one but it still represents a conservative estimation of the radial field component, since it behaves as un upper bound for the exact curve. The developed algorithm is characterized by fast performances in terms of CPU time, lending itself to be used for several applications, including a coupling code for lightning induced overvoltages calculations.