A. G. Temnikov

Using of artificial clouds of charged water aerosol for investigations of physics of lightning and lightning protection

Using of experimental methods for investigation of lightning and lightning protection physics was and is relevant as its help to build or approve the physical and mathematical models of thunderstorm and lightning discharge formation, to check and to analyze detail the possible effectiveness of modern and perspective methods and utilities of lighting protection. Application of artificial strongly charged aerosol clouds opens new possibilities for experimental simulation of the processes in thunderstorm clouds and lightning discharges, significantly approximates the physical simulation of process of object lightning affection to real thunderstorm situation. Paper presents the results of the using of artificial clouds of charged water aerosol for investigations of lightning and lightning protection physics.

Initiation of lightning in thunderclouds with the use of artificial clouds of charged aerosol

Results of the experimental simulation of lightning initiation processes in thunderclouds by large hydrometeor arrays using artificial clouds of charged water aerosol of negative and positive polarity are presented in this paper. A significant influence of the hydrometeor arrays on the discharge initiation and propagation between the charged cloud and the ground is shown. It is found that cloud polarity has a significant influence on the probability of discharge initiation by the hydrometeor array. It is established that hydrometeors have the most pronounced influence on the discharge initiation in positively charged aerosol clouds. Character types of the discharge phenomena initiated by the hydrometeors in the clouds of negative and positive polarity are found: cloud discharges, channel discharges, and diffuse discharges. It is established that the characteristic frequency ranges in the wavelet spectrum of electromagnetic radiation of such discharge phenomena initiated by hydrometeors have greater values for a negative polarity of a cloud than for a positive one. It is found that the characteristics of the current impulse of the main stage of the discharge between the cloud and the ground forming with the participation of hydrometeors differ from the analogous characteristics for cases in which hydrometeors are absent in the gap between the charged cloud and the ground. Thus, using artificial clouds of charged aerosol opens new possibilities for investigation of the processes of lightning initiation in thunderclouds.

The influence of artificial-thunderstorm cell polarity on discharge initiation by model hydrometeor arrays

The initiation of discharge by model hydrometeors between an artificial-thunderstorm cell (aerosol cloud) of negative or positive polarity and ground has been experimentally studied. It is established for the first time that the conditions of cloud–ground spark discharge initiation by hydrometeors, as well as the characteristics of discharge significantly depend on the polarity of charged cloud. The effect of hydrometeor arrays can be manifested by the cloud–ground lightning initiated in a thundercloud and used for developing scientific principles of artificial lightning discharge.

On a criterion of the appearance of an upward leader from ground-based objects

Results of an experimental study of processes forming an upward leader discharge from a grounded rod electrode in the electric field of an artificial cloud of charged water aerosol are presented. The transition of the streamer corona flash to an upward leader discharge was found to be of a probabilistic character and to be determined, first of all, not by the current amplitude, and not only by the flash charge passing through the stem of the pulse corona, but by a set of parameters: duration of the current passage at a rather high level and optimum value of the corona charge passed through the stem base. The range of radii of curvature of the rod-shaped lightning arrester tip (from 20 to 25 mm) at which the highest probability of the appearance of an upward leader is observed has been revealed.

Investigation of compacted and extended objects lightning protection effectiveness on models using artificial clouds of charged water aerosol

Results of the experimental investigations and physical simulation of the processes of lightning affection of the compacted and extended objects on models and the investigation of its lightning protection effectiveness using artificial charged aerosol clouds are presented. Peculiarities of affection of the grounded objects by the discharges from artificial charged aerosol clouds are presented and analyzed. Influence of the characteristics of lightning rod and object models (or lightning conductor and phase wire models) on the process of their affection by the discharge from charged aerosol has been analyzed. Comparison of the experimental results with the calculated and experimental methods of determination of the compacted and extended object lightning protection (in context of power objects) has been fulfilled. Recommendations on the improvement of lightning protection of the existing and projecting power energy objects have been proposed.

Initiation of Spark Discharges between Artificial Thunder Cells Using a Hydrometeor

This paper presents the results of an experimental investigation of the influence of model hydrometeor arrays on the initiation and propagation of the spark discharges between the artificial thunder cells of the negative and positive polarity. It is specified that introduction of the negative and positive polarity of the model hydrometeors of different types joined into the array using the various methods into the gap between the artificial thunder cells, leads to the significant growth of the probability of initiation of the spark discharges between the cells and total length of the forming discharge system. It is stated that the model hydrometeors of the cylindrical form joined into the group using the dielectric string or tape are the most efficient for these purposes. The physical picture of formation of the spark discharges by the groups of the hydrometeors between the artificial thunder cells of the different polarity is constructed considering the possibility of formation of the high-current streamer and volume leader discharges.

The Influence of the Shape of Model Hydrometeors on the Formation of Discharge between an Artificial-Thunderstorm Cell and the Ground

We have experimentally studied how arrays of model coarse hydrometeors influence the initiation and propagation of discharge between an artificial-thunderstorm cell of negative or positive polarity and the ground. It is established for the first time that the probability of initiation and stimulation of a channeled discharge between negatively or positively charged cloud and the ground significantly depends on the shape and size of coarse hydrometeors occurring near the thunderstorm cell boundaries. The obtained results can be used in developing methods for the artificial initiation of the cloud–ground type lightning of both polarities and targeted discharge of thunderstorm clouds.

Initiation of spark discharges between an artificial thunderstorm cell and the ground by hydrometeor groups

The results of experimental simulation of the influence of hydrometeor groups on the probability of initiation of spark channel discharges between an artificial thunderstorm cell of negative or positive polarity and the ground were presented. It has been discovered that there is a significant influence of the kind of hydrometeors and the method of their combination into a group on the initiation and stimulation of sparkdischarge propagation from an artificial thunderstorm cell. It has been revealed that injection of the groups of plate-rhombus hydrometeors sharply increases the probability of initiation of channel discharge from a negatively charged artificial cell. It has been established that volume-cylinder hydrometeors display an analogous behavior for a positively charged cell. It has been found that the simulation of accelerated formation of the spark discharge between neighboring hydrometeors in the group is a necessary condition for the initiation and stimulation of the channel-discharge propagation between the cloud and the ground. It has been revealed that a dielectric string or dielectric tape can be used for such purposes. A multifactor physical picture of hydrometeor influence on the initiation and stimulation of the spark channel discharge between an artificial thunderstorm cell and the ground has been proposed. This may result in promising methods of artificial initiation of lightning using arrays of model hydrometeors.

Stimulation of discharge of an artificial thunderstorm cell by arrays of model hydrometeors

The results of experimental investigation of the influence of model hydrometeor arrays on the stimulation of discharging processes of an artificial thunderstorm cell of negative or positive polarity are presented. It has been revealed that insertion into the thunderstorm cell of model hydrometeors of different kinds brought together in an array by different methods can increase the effectiveness of charged-cloud discharging by several times. It has been established that model hydrometeors of ellipsoid form are most effective for neutralization of the charge of a negatively charged artificial thunderstorm cell. Under conditions of a positive polarity of an artificial thunderstorm cell, its discharge is most effectively provided by model hydrometeors of cylindrical form. It has been revealed that introduction of model hydrometeor arrays also has an effect on the duration of the main discharge stage, during which the artificial thunderstorm cell discharges. It has been shown that the duration of the main stage of discharge initiated by arrays of model hydrometeors of different shapes from a negatively charged artificial thunderstorm cell is several times longer than that for a positively charged cell. The obtained data open up new possibilities for using methods of discharge intensification of a natural thundercloud.

Peculiarities of electromagnetic radiation spectrum of discharges initiated by hydrometeors between artificial thunderstorm cell and ground

Results of experimental investigation of the influence of the hydrometeor array disposed inside the artificial thunderstorm cell and near its boundary on the spectral characteristics of spark discharge between the cloud and the ground and its electromagnetic radiation have presented. Peculiarities of the Fourier and wavelet (wavelet “Mexican hat”) electromagnetic spectrum of discharges forming on the hydrometeor array in the negatively and positively charged aerosol clouds have analyzed. Application of the received results to the electromagnetic radiation from discharge phenomena in natural thunderclouds has discussed.