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The influence of the parameters of sensors and receiving and transmitting devices with dielectric shells on the spectral characteristics of signals induced by an artificial thunderstorm cell (ATC) has been experimentally investigated. Based on wavelet analysis of the signals induced by the ATC, differences in spectral characteristics compared with rod electrodes were established. Four systems of electrodes with dielectric caps are considered, and characteristic spectral ranges corresponding to the formation of flashes of positive streamer corona and negative reverse discharges from the model electrode are determined. It is established that, with an increase in the radius of curvature of the working elements of sensors and antenna devices, higher characteristic frequencies can be expected in the spectrum of current pulses of the streamer corona and negative reverse discharge. It is noted that the characteristic frequency ranges found in the spectra of the current pulse of the positive streamer corona and negative reverse discharge may be present in signals induced in thunderstorm conditions on sensors and receiving–transmitting devices having flat and extended working elements, which can cause false alarms and malfunctions of sensors, analog-to-digital converters and information-transmission devices. [ABSTRACT FROM AUTHOR]

The influence of the parameters of the working elements of sensors and antenna receiving and transmitting devices protected by dielectric caps on the intensity of exposure to atmospheric electricity is experimentally investigated. It is shown that, on extended electrodes, an artificial lightning cell induces more powerful streamer flashes than on concentrated rod electrodes; for reverse discharges, an inverse pattern is observed, which may be related to the area of charge accumulation on the inner surface of the dielectric cap. A relationship has been established between the nature and intensity of the ATC effect on sensor and antenna models and the radius of a cylindrical electrode or the radius of the edge of a flat disk electrode. It is established that, with an increase in the surface area of the electrode that models the working elements of the sensor or antenna receiving and transmitting device, the contribution of bias currents in the recorded total current increases significantly. It is shown that the parameters of the current pulses generated on the protected elements depend on the size and shape of the working area of these elements and on the location and area of charge accumulation on the inner surface of the dielectric cap. [ABSTRACT FROM AUTHOR]

The results of the physical modelling of the formation processes of upward discharges from grounded objects in the artificial thunderstorm cell's electric field are presented. We established the considerable influence of the electrode tip's radius on the pulse streamer corona stem's parameters and, subsequently, on the probability of the transformation of the impulse streamer corona first flash's stem into a first stage of upward leader. We determined the diapason of the optimal tip radii for a lightning rod or lightning conductor, which allows for the most probable formation of the first impulse streamer corona, with the parameters providing the best conditions for the upward leader's start, the purpose of which is the lowering of the probability of lightning striking the object under protection. A considerable difference between the electrical characteristics of the first impulse corona flash with and without the streamer–leader transition was established. It was shown that the amplitude of the streamer corona flash current impulse is considerable, but not the main defining factor of the streamer–leader transition. It is established that the charge value of the streamer corona first flash is not a threshold requirement for the formation of the upward leader from a ground object, but only defines the probability of the successful upward leader formation. Based on the analysis of the experimental data received, we suggest that there is a dependency between the probability of upward positive leader formation from the grounded objects and the charge value of the first pulse streamer corona flash for the rod (centered) and rope (elongated) lightning conductors and objects in the electric field of the thundercloud and downward lightning leader. The obtained results can be used for mathematical modelling of the formation processes of upward discharges from grounded objects in the artificial thunderstorm's electric field, as in a natural thunderstorm situation. [ABSTRACT FROM AUTHOR]

Results of the spectral analysis of electromagnetic signals induced in a model antenna by discharges from an artificial thunderstorm cell involving structural elements made of dielectric and composite materials are presented. The spectral analysis has been performed using the "Mexican Hat" basic wavelet. The influence of the curvature radius of the tip of the initiating model electrode contacting the surface of the dielectric structure on the spectral composition of the induced signals is investigated. The spectral composition of the discharge current during the formation of a streamer corona with a larger radius of tip curvature exhibited characteristic frequencies with higher values that are several times higher. The spectrum of the signal induced on the antenna contains characteristic frequencies that are higher than those in the discharge-current spectrum. The characteristic frequencies of the signal detected by the antenna during the formation in the electric field of a streamer corona and the upward leader from the initiating electrode with a small radius of curvature in contact with the insulator surface were 20% higher than those in the case when the discharge developed from an electrode with a large radius of curvature. During the formation of the main stage of the discharge, the average values of the maximum frequencies of the signal induced in the antenna had similar values. The frequency that corresponds to the maximum intensity of the signal wavelet spectrum tends to decrease with an increase in the steepness of the streamer corona current pulse. In analyzing the possible effects of atmospheric electricity and lightning on elements of monitoring and control systems of power facilities, it is necessary to take into account that the electromagnetic radiation spectrum of discharges developing from structural elements near the surface of composite/dielectric materials includes frequencies up to 70–80 MHz. [ABSTRACT FROM AUTHOR]

Results of physical simulation of the impact of discharge phenomena generated by an artificial thunderstorm cell, which involve structural elements made of dielectric and composite materials, on the elements of control and monitoring systems of power facilities are presented. An increase in the curvature radius of the tip of the model initiating electrode, which is in contact with the surface of the insulating structure, is shown to result in an increase in the amplitude and steepness of the current pulse of the streamer corona and the amplitude of the signal induced in a flat antenna, on average, by a factor ranging from 1.5 to 2, and a decrease in the neutralized charge of the cloud. It has been found that, at the streamer and main stages of the discharge, the amplitude of the current and the flown charge diminish with an increase in the curvature radius of the model electrode tip. The dependences between the maximum value of the signal induced on the antenna and the amplitude of the current at various discharge stages are determined. As the steepness of the current pulse at the streamer and main stages of the discharge between a model electrode with a large curvature radius and an artificial thunderstorm cell increases, with the amplitude of the signal induced in the antenna also increasing. [ABSTRACT FROM AUTHOR]

The article presents the wavelet spectral analysis of signals induced by an artificial thunderstorm cell on dummy elements of OHPL monitoring systems protected by dielectric shells obtained by lightning–cyberphysical interaction modelling. Three types of electrode systems (sensors or transceiver antennas) with model dielectric shells are considered. The characteristic spectral ranges corresponding to the formation of streamer flashes and reverse discharges from a dielectric-embedded model electrode are determined. It is established that the spectral characteristics of the induced signals depend on the model electrode parameters and the dimensions of the dielectric shells. Higher values of maximum frequencies in the signals spectrum (current pulses) are characteristic of smaller dielectric shells. It is established that an increase in the upper chamber of the dielectric-embedded model electrode to a decrease in the average values of the maximum spectrum frequency of the signal recorded on the model electrode during the development of a streamer flash from its top. The presence of frequency ranges of a few to tens of megahertz in the spectrum of signals induced by an artificial thunderstorm cell on dummy elements of OHPL monitoring systems protected by dielectric shells, which can cause false alarms and sensor malfunctions, analog-to-digital converters, and information-transmission devices, is noted. All this should be taken into account when analyzing the possible impact of electromagnetic radiation of atmospheric electricity and lightning on the elements of intelligent monitoring systems and on diagnostics and control of power facilities, which include components made of dielectric and composite materials. [ABSTRACT FROM AUTHOR]

Featured Application: The results of this work can be used to assess the reliability of electric power facilities' monitoring systems during thunderstorms. In addition to direct lightning strikes, the correct operation of monitoring systems can also be influenced by incomplete upward discharges, including those from nearby objects. The results of a physical simulation using negatively charged artificial thunderstorm cells to test the spectrum of possible electromagnetic effects of upward streamer discharges on the model elements of transmission line monitoring systems (sensor or antennas) are presented. Rod and elongated model elements with different electric field amplification coefficients are investigated. A generalization is made about the parameters of upward streamer current impulse and its electromagnetic effect on both kinds of model elements. A wavelet analysis of the upward streamer corona current impulse and of the signal simultaneously induced in the neighboring model element is conducted. A generalization of the spectral characteristics of the upward streamer current and of the signals induced by the electromagnetic radiation of the nearby impulse streamer corona on model elements is made. The reasons for super-high and ultra-high frequency ranges in the wavelet spectrum of the induced electromagnetic effect are discussed. The characteristic spectral ranges of the possible electromagnetic effect of upward streamer flash on the elements of transmission line monitoring systems are considered. [ABSTRACT FROM AUTHOR]

The results of the physical modelling of the formation processes of upward discharges from grounded objects in the artificial thunderstorm cell’s electric field are presented. We established the considerable influence of the electrode tip’s radius on the pulse streamer corona stem’s parameters and, subsequently, on the probability of the transformation of the impulse streamer corona first flash’s stem into a first stage of upward leader. We determined the diapason of the optimal tip radii for a lightning rod or lightning conductor, which allows for the most probable formation of the first impulse streamer corona, with the parameters providing the best conditions for the upward leader’s start, the purpose of which is the lowering of the probability of lightning striking the object under protection. A considerable difference between the electrical characteristics of the first impulse corona flash with and without the streamer–leader transition was established. It was shown that the amplitude of the streamer corona flash current impulse is considerable, but not the main defining factor of the streamer–leader transition. It is established that the charge value of the streamer corona first flash is not a threshold requirement for the formation of the upward leader from a ground object, but only defines the probability of the successful upward leader formation. Based on the analysis of the experimental data received, we suggest that there is a dependency between the probability of upward positive leader formation from the grounded objects and the charge value of the first pulse streamer corona flash for the rod (centered) and rope (elongated) lightning conductors and objects in the electric field of the thundercloud and downward lightning leader. The obtained results can be used for mathematical modelling of the formation processes of upward discharges from grounded objects in the artificial thunderstorm’s electric field, as in a natural thunderstorm situation.

The results of experimental laboratory investigations of possible mechanisms of the impact of lightning and thunderclouds on aircraft radomes and equipment inside them are presented. An artificial thunderstorm cell of negative polarity and model aircraft radomes with lightning diverter strips have been used. Experiments have shown that the discharge processes in a radome model significantly depend on the magnitude of the charge that accumulates on the inner and outer surfaces of the radome shell. It is established that the accumulation of large-magnitude charges of different signs on the outer and/or inner surface of the radome (up to hundreds of µC/m2) shell leads to a multivariance of the mechanisms of development of discharge processes inside the radome model, along its surface, and in the space near it. Significant influence of the “reverse” discharge from the antenna model under the radome on the types of current impulses recorded on the antennas under impact of the artificial thunderstorm cell is established. Peculiarities of the discharge formation in the radome model when using solid and segmented diverter strips for its protection are revealed. Parameters of the current impulses registered on the diverter strips and the antennas have been determined. Based on the conducted research, the possible mechanisms of the impact of thunderclouds and lightning discharges on radio-transparent aircraft radomes and the equipment inside them are considered.

The article represents results of a physical simulation of incomplete upward leader discharges induced on air transmission lines’ elements, using charged artificial thunderstorm cells of negative polarity. The influence of such discharges on closely located model sensors (both of rod and elongated types) of digital monitoring systems, as well as on the models of receiver-transmission systems of local data collection (antennas), was determined. Effect of heterogeneity of electromagnetic field caused by incomplete upward discharges on frequency specter of signals generated on sensors and antennas was estimated. Wavelet analysis was carried out to determine the basic frequency diapasons of such signals. Based on experimental data obtained, suppositions about the extent of influence of nearby incomplete leader discharges on the functioning of currently used systems of transmission lines’ monitoring were made.

The results of a physical simulation using negatively charged artificial thunderstorm cells to test the spectrum of possible electromagnetic effects of upward streamer discharges on the model elements of transmission line monitoring systems (sensor or antennas) are presented. Rod and elongated model elements with different electric field amplification coefficients are investigated. A generalization is made about the parameters of upward streamer current impulse and its electromagnetic effect on both kinds of model elements. A wavelet analysis of the upward streamer corona current impulse and of the signal simultaneously induced in the neighboring model element is conducted. A generalization of the spectral characteristics of the upward streamer current and of the signals induced by the electromagnetic radiation of the nearby impulse streamer corona on model elements is made. The reasons for super-high and ultra-high frequency ranges in the wavelet spectrum of the induced electromagnetic effect are discussed. The characteristic spectral ranges of the possible electromagnetic effect of upward streamer flash on the elements of transmission line monitoring systems are considered.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Results of the experimental simulation of an influence of the lightning diverter strip models on spectral characteristics of discharge phenomena inside aircraft nose radome model, using artificial thunderstorm cell of a negative polarity, have presented. Significant influence of a lightning stripe model type on an amplitude and a form of the signals registered on an antenna model when discharge forms between an artificial thunderstorm cell a nose radome model and on the characteristics of their Fourier and wavelet spectrums has been experimentally established. It was found that the characteristic frequencies in the registered signals are on order higher for the segmented lightning stripes than for the solid lightning diverter stripes. Possible reasons of such differences are discussed in paper. Dependencies between the spectral characteristics of the signal registered on antenna inside a radome model and the parameters of the current impulses of discharge formed on both type of the lightning stripe models being on an external surface of a radome model have been established. Possibility of a correction of a lightning protection system of an aircraft nose radome for the decreasing of a signal intensity induced on antenna due to lightning, atmospheric and static electricity action has been analyzed and experimentally check including the frequency region dangerous for the radar and the computer equipment connected with them. [ABSTRACT FROM AUTHOR]

Results of an investigation of the peculiarities of a spectrum of the electromagnetic signals induced nearby discharges between an artificial thunderstorm cell and a ground have presented. It was experimentally found that the impulse current parameters and an intensity, form, spectral characteristics of the induced electromagnetic signals depend on a variant of a discharge formation from an artificial thunderstorm cell (upward discharge, downward discharge, or counterpart discharge). Significant difference of the wavelet spectrum characteristics of the electromagnetic signals registered by the antennas in the vicinity of discharge formation has been found for these three variants. Significant difference of the spectral characteristics of the electromagnetic signals induced on nearby antennas during the time of the first and subsequent current impulses of a discharge between an artificial thundercloud and a ground: in average, subsequent discharges have more less characteristic frequencies. Possible reasons of that differences have discussed in paper. Role of the powerful streamer discharges during the main stage formation in the appearance of the ultrahigh frequency range of the induced electromagnetic signals has considered. Some dependencies between the spectral characteristics of signals registered by antennas and the parameters of the current impulses for the different variants of the main stage of the discharge between the artificial thunderstorm cell and the ground have been established. The possibility of applying the results obtained for improving the operation of lightning direction finding systems is being considered. [ABSTRACT FROM AUTHOR]

The results of experimental laboratory investigations of possible mechanisms of the impact of lightning and thunderclouds on aircraft radomes and equipment inside them are presented. An artificial thunderstorm cell of negative polarity and model aircraft radomes with lightning diverter strips have been used. Experiments have shown that the discharge processes in a radome model significantly depend on the magnitude of the charge that accumulates on the inner and outer surfaces of the radome shell. It is established that the accumulation of large-magnitude charges of different signs on the outer and/or inner surface of the radome (up to hundreds of µC/m2) shell leads to a multivariance of the mechanisms of development of discharge processes inside the radome model, along its surface, and in the space near it. Significant influence of the "reverse" discharge from the antenna model under the radome on the types of current impulses recorded on the antennas under impact of the artificial thunderstorm cell is established. Peculiarities of the discharge formation in the radome model when using solid and segmented diverter strips for its protection are revealed. Parameters of the current impulses registered on the diverter strips and the antennas have been determined. Based on the conducted research, the possible mechanisms of the impact of thunderclouds and lightning discharges on radio-transparent aircraft radomes and the equipment inside them are considered. [ABSTRACT FROM AUTHOR]

The article represents results of a physical simulation of incomplete upward leader discharges induced on air transmission lines' elements, using charged artificial thunderstorm cells of negative polarity. The influence of such discharges on closely located model sensors (both of rod and elongated types) of digital monitoring systems, as well as on the models of receiver-transmission systems of local data collection (antennas), was determined. Effect of heterogeneity of electromagnetic field caused by incomplete upward discharges on frequency specter of signals generated on sensors and antennas was estimated. Wavelet analysis was carried out to determine the basic frequency diapasons of such signals. Based on experimental data obtained, suppositions about the extent of influence of nearby incomplete leader discharges on the functioning of currently used systems of transmission lines' monitoring were made. [ABSTRACT FROM AUTHOR]