Atmospheric Electrical Discharges Research Articles

Continuous spark plasma synthesis of Au/Co binary nanoparticles with tunable properties

We present here a scalable and environmentally friendly gas phase technique employing atmospheric pressure electrical spark discharge plasmas for the production of Au/Co binaries, an effective catalyst system for the decomposition of hydrogen-rich compounds, such as ammonium borane. We demonstrate that Au/Co alloy nanoparticles can be produced via the spark plasma-based technique. The possibility of varying the morphology and phase structure via real time heat treatment of the generated aerosol to form Au/Co/CoO particles with continuous control over a wide particle compositional range (from 24 to 64 at.% [Co]/([Co] + [Au]) content) is also demonstrated. Since our spark-based approach is proven to be capable of providing reasonable particle yields, these results may contribute to the transition of lab-scale, nanocatalyst-based hydrogen storage systems to real world applications.

Extreme hydroxyl amounts generated by thunderstorm-induced corona on grounded metal objects

Atmospheric electrical discharges are now known to generate unexpectedly large amounts of the atmosphere's primary oxidant, hydroxyl (OH), in thunderstorm anvils, where electrical discharges are caused by atmospheric charge separation. The question is "Do other electrical discharges also generate large amounts of oxidants?" In this paper, we demonstrate that corona formed on grounded metal objects under thunderstorms produce extreme amounts of OH, hydroperoxyl (HO2), and ozone (O3). Hundreds of parts per trillion to parts per billion of OH and HO2 were measured during seven thunderstorms that passed over the rooftop site during an air quality study in Houston, TX in summer 2006. A combination of analysis of these field results and laboratory experiments shows that these extreme oxidant amounts were generated by corona on the inlet of the OH-measuring instrument and that corona are easier to generate on lightning rods than on the inlet. In the laboratory, increasing the electric field increased OH, HO2, and O3, with 14 times more O3 generated than OH and HO2, which were equal. Calculations show that corona on lightning rods can annually generate OH that is 10-100 times ambient amounts within centimeters of the lightning rod and on high-voltage electrical power lines can generate OH that is 500 times ambient a meter away from the corona. Contrary to current thinking, previously unrecognized corona-generated OH, not corona-generated UV radiation, mostly likely initiates premature degradation of high-voltage polymer insulators.

Transient Process at Atmospheric Discharge into the Landline and the Appearance of an Electric Arc in the Switch

This document proposes a model of the process of atmospheric discharge of overhead lines followed by an electric arc. The intensity of atmospheric discharges, followed by electric arc and destruction, is determined by the difference in potential and current. Such a structure and form of discharge make it difficult to analyze the transient process and obtain adequate solutions. That is why the model of the transient process in the electric arc of the switch under the conditions of interruption of the AC circuit is specially analyzed. Simple equivalent schemes for the analysis of phenomena with given values of linear parameters are presented, which are very simple to apply. All influential parameters by which the overvoltage values in the model can be estimated were also taken into account. The evaluation of the proposed model was performed using the adapted MATLAB program psbsurlightcuurent for atmospheric electrical discharge, which contains a high frequency current source. The verified simulation method was used to verify the results as part of a method derived from artificial intelligence algorithms. The process simulation program, the obtained voltage and current diagrams confirm the application of the simulation algorithm model.

Processing of passive EM fields acquired during active-source airborne EM surveys

The recording of raw or streamed airborne electromagnetic (AEM) data, as done by CGG during MEGATEM surveys, allows for the extraction of passive EM signals also present, but not normally processed. These include (1) powerline responses, (2) responses in the very low frequency (VLF) range due to radio transmissions and (3) natural-source audio-frequency magnetic (AFMAG) and VLF responses in the frequency range 25 Hz–25 kHz extracted from individual atmospheric electrical discharges (sferics). The latter approach manages to extract good signal in the audio-frequency magnetotelluric (AMT) dead band (1–5 kHz) for one of the discussed data sets. The recording of the three-component AEM data allows for the vector processing of these passive EM responses, including the derivation and modelling of the vertical-to-horizontal magnetic field ratio (tipper) data. Conductivity information can be derived from the tipper data with an apparent conductivity transformation and, more rigorously, with 2D and 3D inversions that take into account the terrain’s topography. The extraction and modelling of passive EM responses is demonstrated on two data sets. A powerline apparent-conductivity grid derived from a MEGATEM survey near Timmins, Canada indicates conductivity structures similar to those in the corresponding active-source EM data. VLF and AFMAG responses derived from South American MEGATEM data show a strong correlation to topography. These data were successfully modelled with 2D and 3D inversions, and the derived shallow conductivity structures confirm and complement the information extracted from the active-source EM data.

Observation of the onset of a blue jet into the stratosphere.

Blue jets are lightning-like, atmospheric electric discharges of several hundred millisecond duration that fan into cones as they propagate from the top of thunderclouds into the stratosphere1. They are thought to initiate in an electric breakdown between the positively charged upper region of a cloud and a layer of negative charge at the cloud boundary and in the air above. The breakdown forms a leader that transitions into streamers2 when propagating upwards3. However, the properties of the leader, and the altitude to which it extends above the clouds, are not well characterized4. Blue millisecond flashes in cloud tops5,6 have previously been associated with narrow bipolar events7,8, which are 10- to 30-microsecond pulses in wideband electric field records, accompanied by bursts of intense radiation at 3 to 300 megahertz from discharges with short (inferred) channel lengths (less than one kilometre)9-11. Here we report spectral measurements from the International Space Station, which offers an unimpeded view of thunderclouds, with 10-microsecond temporal resolution. We observe five intense, approximately 10-microsecond blue flashes from a thunderstorm cell. One flash initiates a pulsating blue jet to the stratopause (the interface between the stratosphere and the ionosphere). The observed flashes were accompanied by 'elves'12 in the ionosphere. Emissions from lightning leaders in the red spectral band are faint and localized, suggesting that the flashes and the jet are streamer ionization waves, and that the leader elements at their origin are short and localized. We propose that the microsecond flashes are the optical equivalent of negative narrow bipolar events observed in radio waves. These are known to initiate lightning within the cloud and to the ground, and blue lightning into the stratosphere, as reported here.

Dynamics of Disturbances Caused by Local Sources of Heat Release in the Earth’s Damp Atmosphere

The stability of a layer of moist air above a heated surface of land or ocean is studied under the sudden influence of internal sources of heat release, which depend on the pressure and density. A dispersion equation is obtained for small 3D perturbations in a rotating atmosphere. It contains the previously known waves (acoustic, internal waves, and Brunt–​​Vaisala waves) and makes it possible to obtain a modified criterion for the onset of convective instability. This dispersion equation also makes it possible to study the effect of internal heat release on the dynamics of perturbation in these waves, including the conditions for the occurrence of instability generated by an atmospheric electric discharge. Taking into account new considered effects can lead to the identification of new instabilities and the modification of the previously known ones. The proposed system of equations allows numerical calculations of vortex flows in moist air in the near-surface layer and a more detailed study of the mechanisms of the beginning of hurricanes and tornadoes.

POWERFUL HIGH-CURRENT GENERATOR OF MICROSECOND VOLTAGE PULSES WITH VOLTAGE AMPLITUDE UP TO ±2 MV AND CURRENT AMPLITUDE UP TO ±150 kA WITH ELECTRIC ENERGY STORED IN CAPACITORS UP TO 1 MJ

Purpose. Development and evaluation, on the basis of existing ultra-high-voltage generator of pulsed voltages and currents of GINT-4 type, of the new scheme of design of its charging-discharging circuit (CDC), and creation of modernized powerful ultra-high-voltage high-current generator of GINT-2 type to form microsecond voltage pulses with amplitudes up to ±2 MV and current with amplitude up to ±150 kA in the electrical load, with electrical energy stored in its capacitive energy storage (CES) up to 1 MJ. Methodology. Fundamentals of theoretical and applied electrical engineering, electrical power engineering, electrophysical principles of high-voltage and high pulsed current engineering, fundamentals of electromagnetic compatibility (EMC), instrument engineering, high-voltage instrumentation and standardization. Results. The new scheme of design of CDC of the modernized powerful ultra-high-voltage, heavy-current generator of GINT-2 type of outdoor placement, that allows obtaining, with preservation of the main electrotechnical elemental base of existing powerful prototype generator GINT-4 (rated output voltage ±4 MV with rated electrical energy stored in CES of 1 MJ and maximal amplitude of output current pulse in electrical load up to ±75 kA) pulses of current of microsecond duration with doubled amplitude (up to ±150 kA) in the long (from 1 to 4 m length) air gap of standard two-electrode discharging «needle-plane» system, in comparison with parameters of current pulses with amplitudes up to ±75 kA that are formed in the discharging circuit of generator of GINT-4 type with the use of the analogous air discharging system, has been developed. Experimental evaluations of the developed new discharging circuit in CDC of the modernized generator of GINT-4 type has been performed in field conditions, and its advantages over the old discharging circuit in composition of CDC of generator of GINT-4 type have been shown. Calculated evaluations of rise rates of high pulsed current (HPC) in plasma channel of air spark discharge of CES with energy up to 1 MJ of generator of GINT-2 type, and strength of electric and magnetic field that are formed around this high-current channel of spark discharge and are powerful electromagnetic interference (PEMI) for objects of armaments and military equipment (OAME) were performed. It was shown that rise rates of HPC obtained for generator GINT-2 in the channel of long air spark discharge (of artificial lightning) and PEMI around this channel practically satisfy strict requirements of the NATO Standards AESTP-250: 2014 and USA MIL-STD-464C: 2010. Originality. The new scheme of design of CDC in composition of the modernized powerful ultra-high-voltage high-current generator of GINT-2 type (developer – Research & Design Institute «Molniya» of NTU «KhPI»), satisfying requirements of the mentioned standards for full-scale tests of OAME for EMC and immunity to action on them of PEMI from long atmospheric spark electric discharges (lightning) was developed for the first time. Practical value. Application of the created ultra-high-voltage high-current generator of GINT-2 type in tests of OAME for EMC and immunity to action on them of PEMI from artificial lightning will assist increase in reliability of OAME functioning in conditions of damaging (destabilizing) action on them HPC and PEMI of natural and artificial origin.

Teaching physics through contextualized concept cartoons

This document present the results of a research in the use of Cartoon in teaching of physics. The methodology of mixed approach, involved at first the design and use of Concept Contextualized Cartoons, as well their validation and implementation among groups of high school students. Secondly, a motivational scale regarding the use of cartoons and the teaching of physics was adapted and applied. The results describe the characteristics of the questions formulated by the students when interacting with the cartoon, specifically in relations the scientific knowledge associated to three phenomena of study: Atmospheric Electric discharges – Thunderbolt, Electric Current and Polarization. Furthermore, the cartoons didactic potential was identified in relation to the categories of the motivational scale, which highlights significant motivational levels associated with the relationship with life and the importance of the physics class.

PREDICTION OF OCCURRENCE OF CLOUD-TO-GROUND ELECTRICAL DISCHARGES USING FORECASTS OF THE BRAMS NUMERICAL MODEL

The prediction of occurrence of severe convective events allows to issue meteorological alerts in order to reduce potential catastrophic events. In many cases, numerical models for weather forecast are not able to efficiently simulate such events. Alternatively, considering the large amount and diversity of meteorological data, the employment of Data Mining techniques has become widespread. In the case of convective activity, the use of past data allows to identify characteristic patterns in the model forecasts by associating them to the corresponding field of density of occurrence of cloud-to-ground atmospheric electrical discharges. Such task is performed by a machine learning algorithm, in this case, a set of neural networks. As a consequence, these patterns can be detected in future forecasts generated by the numerical model, allowing to predict the occurrence of discharges, which are associated to convective activity. In the current work, the proposed approach was applied to BRAMS, a numerical model developed in the country for operational and research use in Meteorology. Consequently, the ability to predict the occurrence of discharges by the set of neural networks was analysed for some selected events as well as its usefulness as an ancillary tool in operational weather forecast.

Об истории открытия и природе алмазов в вулканических породах Камчатки

The history of the discovery of diamonds in the products of Kamchatka volcanic eruptions is briefly described, and the results of comprehensive studies of Tolbachin diamonds including crystallomorphology, faceted sculptures, xenomineral greases and films on the surface, nanomicroswitches, impurity elements, spectroscopic properties, isotopic composition of carbon and nitrogen are summarized. The conclusion is drawn about the natural origin of the Tolbachin diamonds formed directly in the volcanic ash-gas cloud by crystallization from gases stimulated by atmospheric electric discharges.

Pražnjenje u nanosekundama pri atmosferskom pritisku od neuniformne elektrode (vrh) prema ravnoj elektrodi

Pražnjenje u nanosekundama pri atmosferskom pritisku od neuniformne elektrode (vrh) prema ravnoj elektrodi

Design of a UWB biconical antenna with a lightning protection system for surveillance applications

AbstractThis article presents, to the best of our knowledge, the study, software simulation and fabrication of a biconical antenna with a lightning protection system operating in a wide frequency range from 20 MHz to 3 GHz. The purpose of this system is to provide protection against atmospheric electric discharge in regions with a high incidence of lightning.

Thunderstorm charge structures producing gigantic jets

Gigantic jets are atmospheric electrical discharges that propagate from the top of thunderclouds to the lower ionosphere. They begin as lightning leaders inside the thundercloud, and the thundercloud charge structure primarily determines if the leader is able to escape upward and form a gigantic jet. No observationally verified studies have been reported on the thundercloud charge structures of the parent storms of gigantic jets. Here we present meteorological observations and lightning simulation results to identify a probable thundercloud charge structure of those storms. The charge structure features a narrow upper charge region that forms near the end of an intense convective pulse. The convective pulse produces strong storm top divergence and turbulence, as indicated by large values of storm top radial velocity differentials and spectrum width. The simulations show the charge structure produces leader trees closely matching observations. This charge structure may occur at brief intervals during a thunderstorm’s evolution due to the brief nature of convective pulses, which may explain the rarity of gigantic jets compared to other forms of atmospheric electrical discharges.

System-level model and experiments for irrigation water alkalinity reduction and enrichment using an atmospheric pressure dielectric barrier discharge

The treatment of distilled water with varying amounts of dissolved sodium bicarbonate (representing alkalinity) is considered using an atmospheric pressure electrical discharge. The discharge ignited between a capillary tube (used as powered electrode) and a ground electrode wrapped around the beaker holding the treated water consists of streamers propagating in ambient air and striking the water surface. The streamer interaction with water is shown to lead to a decrease in pH and an increase in nitrate concentration. The pH variation with time is shown to be similar to a titration curve for acid-base neutralization with final pH values around 3 for 22 min of treatment. The nitrate ion concentration increase with time is consistent with a two-rate system-level model that is characterized by two asymptotic rates for NO3− creation by the plasma. The two asymptotic rates are calibrated to be about 2.7 μmol/min and 22.5 μmol/min with the transition between the two rates occurring at the breakeven time that is representative of the time required for all dissolved bicarbonate to be consumed by the plasma treatment. The increase in rate of NO3− creation at the breakeven time is attributed to the increase in conductivity of the treated solution once all bicarbonate is consumed thereby modifying the plasma properties. Another system-level model that is based on the observed pH variation is also considered for comparison with measured data. While both system-level models have some discrepancies with the measurements, the two-rate model based on the nitrate ion concentration is concluded to be more useful for determining the NO3− formation rates in the context of irrigation water enrichment. The discrepancies are attributed to the simplicity of the system-level models considered here where the effect of the plasma is completely represented by the creation of just one chemical species in HNO3 thereby neglecting potentially important species such as HNO2 and H2O2. Nevertheless, the proposed system-level model could greatly assist in the design of plasma treatment systems with specified alkalinity, pH and nitrate ion levels for irrigation water.

Fast, Upward, Long-Lasting, Transit Echoes as an Evidence of New-Type of Meteor-Trail Leader Discharge in the Summer Polar Upper Mesosphere

Non-specular, vertically upward transit, fast-moving radar echoes are observed in the summer polar upper mesosphere near 90 km using 52 MHz VHF radar at Esrange, Sweden. By resolving maximum echo power movement, the unusual meteor trails propagate vertically upward with taking horizontal displacements at an initial speed of 10 km/s exponentially decreasing with increasing height from 85-89 km, lasting for 3.5 sec. Another upward transit is observed as following a downward transit echo target in about ~1 sec, lasting over 5 sec. The upward motion cannot be explained with the dynamics of penetrating meteors or by atmospheric dynamics. The observation proposes that secondary produced plasma jets occurring from meteor trail are possibly responsible for upward fast moving echoes. The long-lasting (3-5 sec), ascending meteor trails at speeds of a few 104 m/s are distinctive from any previous occurrences of meteors or upper atmospheric electrical discharges in the aspect of long-lasting upward/downward motions. This result possibly suggests a new type of meteor-trail leader discharge occurring in the summer polar upper mesosphere and lower thermosphere.

Synoptic patterns for days with intense atmospheric electrical activity from 2013 to 2015

The following study aimed to analyze data from Atmospheric Electric Discharge (AEDs) from the period between 2013 to 2015, with the objective of obtaining atmospheric patterns for the days with the maximum AED detected near the city of Santa Maria, in the state of Rio Grande do Sul. Data from the Sferics Timing and Ranging NETwork (STARNET) have been used. With a FORTRAN routine, a search at the AED data was performed to obtain the daily maximum of AED in an area of 1 ° per 1 ° centered in the city Santa Maria.One day of each year were found with maximum numbers of AEDs.The gridded atmospheric dataset used to dynamic and thermodynamic analysis were the final analysis from the National Centers for Environmental Prediction (NCEP).The main characteristics found were the proximity of the equatorial entrance of the high-level jet streak and the thermodynamics indices indicating moderate-to-high possibility for storm occurrence. This analysis enabled in the atmospheric characterization associated to events with large daily amount of DEAs and can be used to improve forecast.

Mineralogical and compositional features of rock fulgurites: A record of lightning effects on granite

Fulgurites are a naturally occurring glass formed when sand, rock, or soil is struck by atmospheric electrical discharges (lightning). The aim of this paper is to provide insights into the conditions occurring in rocks during the lightning strike. Rock fulgurites collected from Mt. Mottarone, Baveno (Piedmont, Italy) have been investigated to assess the mineralogical and compositional changes occurring in granite due to a lightning strike. X-ray powder diffraction showed that the samples represent the dominant granitic rock type of the Baveno massif, the so-called “Pink Baveno.” Fulgurite coats the surface of the granite as a brown-black, glassy to very fine-grained porous layer. Powder diffraction data for the fulgurite reveal the presence of cristobalite and quartz crystals in a glass matrix, suggesting that temperature exceeded ~1700 °C at near atmospheric conditions, assuming thermodynamic equilibrium. Electron probe microanalysis of the glass revealed that it is mainly composed of SiO 2 and Al 2 O 3 and that it has a porosity of 5–7 area% in the studied zones. The presence of the amorphous phase indicates that the abrupt electrical (Joule) heating of the rock surface yielded high temperatures, producing a thin melt layer on the surface, which then cooled adiabatically. Idealized physical model was developed to simulate the effects of Joule heating and subsequent thermal conduction close to the rock surface during and after a lightning strike. The quantity of organic matter in the glass, obtained via Elemental Analyzer, suggests that rapid quenching of the melt trapped NO x and CO x gases produced during heating. Raman spectroscopy revealed the presence of polyaromatic hydrocarbon molecules, which, combined with the Elemental Analyzer data, suggest that organic matter was pyrolyzed at around 300–350 °C and then trapped in the glass matrix of the studied rock fulgurites.

La interdisciplinariedad en la ciencia del rayo

Este artículo sobre la investigación del fenómeno del rayo ha sido elaborado para la posesión como Miembro de Número de la Academia Colombina de Ciencias Exactas, Físicas y Naturales. El fenómeno natural ha sido investigado sistemáticamente en Colombia desde hace aproximadamente cuatro décadas motivado por la curiosidad científica para comprender la alta mortalidad de sistemas, equipos y de personas. Con base en el desarrollo de una hipótesis de investigación se fueron confrontando sus resultados con la realidad concreta, mediante el método científico inductivo y la categoría conceptual de un trabajo interdisciplinario con vínculos dialecticos y la intersección e integración de saberes como la física, las matemáticas, la química, la biología, la historia, la literatura y la psicología social. Con los resultados de investigación se ha logrado aportar nuevo conocimiento del fenómeno en el concierto mundial con libros, artículos científicos, patentes, innovaciones tecnológicas para aplicaciones en protección contra rayos, normas y reglamentos técnicos y apropiación social de la ciencia. Este articulo presenta los logros científicos y tecnológicos realizados en Colombia en el campo de las descargas eléctricas atmosféricas, y propone, basado en las condiciones específicas intertropicales, los focos de investigación de interés para el país en el futuro. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat.

On the biophysical mechanism of sensing atmospheric discharges by living organisms

Atmospheric electrical discharges during thunderstorms, and the related electromagnetic fields (EMFs)/waves called sferics, can be sensed by humans at long distances through a variety of symptoms, mainly headache, fatigue, etc. Up to today there is no explanation for this association. Sferics consist of partially polarized electromagnetic pulses with an oscillating carrier signal in the very low frequency (VLF) band and a pulse repetition frequency in the extremely low frequency (ELF) band. Their ELF intensity may reach ~5mV/m at global ranges, and ~0.5V/m at ~1000km from the lightning. The health symptoms associated with sferics are also associated with antennas of mobile telephony base stations and handsets, which emit radio frequency (RF) radiation pulsed on ELF, and expose humans at similar or stronger electric field intensities with sferics. According to the Ion Forced-Oscillation mechanism, polarized ELF EMFs of intensities down to 0.1–1mV/m are able to disrupt any living cell's electrochemical balance and function by irregular gating of electro-sensitive ion channels on the cell membranes, and thus initiate a variety of health symptoms, while VLF EMFs need to be thousands of times stronger in order to be able to initiate health effects. We examine EMFs from sferics in terms of their bioactivity on the basis of this mechanism. We introduce the hypothesis that stronger atmospheric discharges may reasonably be considered to be ~70% along a straight line, and thus the associated EMFs (sferics) ~70% polarized. We find that sferics mainly in the ELF band have adequate intensity and polarization to cause biological/health effects. We provide explanation for the effects of sferics on human/animal health on the basis of this mechanism.

Role of electric discharges in the generation of atmospheric vortices

The existing thermohydrodynamic and hydroelectromagnetic models of tornado are considered. The potentialities of the humid atmosphere as a heat engine generating air vortices are analyzed in detail. The ability of long-term atmospheric electric discharges to form a tornado funnel and create an initial twist of up to 10–3–10–2 s–1 in it are estimated. The possible effect of a lightning discharge on the initiation and evolution of the tornado is discussed. It is shown that the electric current flowing along the lightning channel can lead to helical instability and generation of a weak primary vortex. The channel formed in the atmosphere by a lightning discharge and the vortex motion of the parent thundercloud can enhance the primary vortex and promote its transformation into a tornado. Possible mechanisms of enhancement of the primary vortex created by a lightning discharge and the possibility of its transformation into a tornado in the postdischarge stage are discussed.