Atmospheric Electrical Discharges Research Articles

Optical properties and chemical behavior of Laser-dye Coumarin-500 and the influence of atmospheric corona discharges

Structure elucidation of Coumarin-500 Laser-dye in cyclohexane at room temperature has been studied by UV–Vis, Raman, and FTIR spectroscopic techniques. Optical properties and chemical behavior under the influence of atmospheric positive electric pulsed corona discharges were also examined. The effects of UV–Vis irradiation changed some optical parameters, such as decrease in optical density on the absorption spectrum and formation of photoproducts, due to the chromaticity removal. No significant optical changes were observed in the light absorption upon UV-irradiation but large changes in absorption spectrum were observed after positive electric corona discharge treatments, FTIR and Raman spectra in non-polar solvent are recorded and interpreted.

Atmospheric electric discharge into water

Results are presented from experimental studies of spark discharges excited between a needle electrode placed over the water surface and a plane electrode immersed in water. The electron density in the spark channels gliding over the water surface and the velocity of their radial propagation are determined. It is found that, when the discharge channel reaches the water, the conductivity of the water surface becomes anomalously high, which looks like a peculiar kind of transformation of a needle electrode over the water surface into a plane electrode adjacent to this surface.

Power ultrasound interaction with DC atmospheric pressure electrical discharge

The effect of power ultrasound application on DC hollow needle to plate atmospheric pressure electrical discharge enhanced by the flow of air through the needle electrode was studied experimentally. It was found that applying ultrasound increases discharge volume. In this volume take place plasmachemical processes, used in important ecological applications such as the production of ozone, VOC decomposition and de-NOx processes enhancement. In our experiments we used a negatively biased needle electrode as a cathode and a perpendicularly placed surface of the ultrasonic resonator – horn – as an anode. To demonstrate the effect of ultrasound waves on electrical discharge photographs of the discharge for the needle to the ultrasonic resonator at distances of 4, 6 and 8 mm are shown. By varying the distance between needle and the surface of the transducer, we were able to create the node or the antinode at the region around the tip of the needle, where the ionization processes are effective. In our experimental arrangement the amplitude of acoustic pressure at antinode exceeded 10 4 Pa. The photographs reveal that the diameter of the discharge on the surface of the ultrasonic horn is increased when ultrasound is applied. The increase of discharge volume caused by the application of ultrasound can be explained as a combined effect of the change of the reduced electric field E/ n ( E is electric field strength and n is the neutral particles density), strong turbulence of the particles in the discharge region caused by quick changes of amplitudes of the standing ultrasonic wave and finally by the boundary layer near the ultrasonic transducer perturbations due to vibrations of the transducer surface.

Streamers and diffuse glow observed in upper atmospheric electrical discharges

A telescopic imaging system was designed to observe fine structure in high-altitude lightning-related electrical discharges known as "sprites". Hundreds of sprites were observed and much of the fine structure can be categorized in terms of streamer and diffuse glow discharges. A streamer/diffuse glow transition occurs at varying altitudes and is dependent on the ambient mesospheric/lower ionospheric conductivity profile. Both stationary and dynamic beading is observed and this feature is currently unexplained by prevailing sprite theories.

On equatorial geophysics studies: a review on the IGRGEA results during the last decade

During the years 1993–1994, a continuous campaign of measurements has been held in the frame of the International Equatorial Electrojet Year (IEEY) with a network of 10 magneto-telluric stations and a network of three ionosondes. Other instruments have participated during shorter periods, HF radar and optical Fabry-Perot 630 nm interferometer. After the IEEY campaigns, the International Group of Research in Geophysics in Europe Africa (IGRGEA created in January 1995), has organized the research in geophysics. This paper report the main results of the IGRGEA during the last decade at local, regional and planetary scales. At a local scale, the HF radar data highlighted the complex structure of echoes in the equatorial zone and allowed to explain the “necklace” echoes as due to oblique propagation into the type I instability levels. This radar observed atmospheric storm electric field discharges at Es layer for the daytime and Equatorial Spread F at night-time. A series of original results concern Doppler spectra and the electric field change on plasma drifts across the ionosphere, gravity waves effects as well the ESF multi-process sources. At a regional scale, magnetic data were used to parametrize the Equatorial Electrojet (EEJ). Ionospheric data, magnetic data and UARS satellite were brought together as input parameters of the Richmond's EEJ model to reproduce the EEJ and the magnetic field variations associated to EEJ. The comparisons between magnetic data, and the magnetic field computed from the physical model and from the parametrization of the EEJ are all in good agreement. Ionosonde data were included in the IRI. Ionosonde data revealed the field aligned f 0 F 2 crests of ionization at mid morning and early afternoon hours. Measurements of equatorial night-time wind variations, obtained for the first time over African equatorial zone with the Fabry-Perot interferometer, shown the strong variability of atmospheric winds. At a planetary scale, the parametrization of the EEJ was done using the magnetometers chain involved during IEEY in the three longitude sectors. Finally, we present the results on electrodynamic coupling between high and low latitudes with overshielding or shielding events.

Introduction to planetary electrodynamics: A view of electric fields, currents and related magnetic fields

The environment surrounding a planet is composed of plasma, ionized gases and a neutral atmosphere that are continuously under the influence of solar effects. The complex dynamical interactions among these media and the generated electric fields create complicated interrelated current systems in the magnetosphere, ionosphere and atmosphere of the planets. Electric fields, currents and the related magnetic disturbances constitute the planetary electrodynamics scenario that will be considered in this tutorial. Beside providing a comprehensive and integrated view of the planetary electrodynamics, this tutorial intends to introduce the necessary theoretical background to understand the physical processes involved and particularly, to discuss some topics in which the authors are currently focussing their interests: Sun–Earth electrodynamical coupling, numerical simulations, plasmaspheric electron content variability, atmospheric electrical discharges, and the effects of intense magnetic storms at the Earth’s surface and in the magnetic anomaly region. New results on these subjects are also presented. A deeper and broader comprehension of this complex scenario involving multidisciplinary investigations will certainly bring several implications in the observational, theoretical, computational and technological developments, with repercussions in biological and medical sciences.

Using Open Atmospheric Electric Discharge for Water Purification from Surface Contamination with Oil Products

The characteristics of open atmospheric dc discharge between a liquid nonmetal cathode (tap water layer) and a metal anode have been studied. The effect of discharge on a layer of oil products (diesel fuel, lubricant oils) contaminating the liquid cathode surface was determined. The discharge current-voltage characteristics and the dependence of the cathode current density on the discharge current I were measured in the interval 20 mA ≤ I ≤ 300 mA for the discharge gap width varied within h = 2–10 mm. For h ≥ 4 mm and I ≥ 120 mA, the cathode current density and the interelectrode voltage are independent of the discharge current, which is characteristic of the normal glow discharge. Under the action of discharge, oil products in the contamination layer on the liquid cathode surface are partly decomposed and partly converted, after which the conversion products can be readily removed from the surface by mechanical methods. The efficiency of contaminant removal can reach 98%. Analysis of the conversion products showed that they are composed of polymer chains with variable length and structure involving oxygen-containing groups.

Ozone and Nitrogen Oxides Generation in Gas Flow Enhanced Hollow Needle to Plate Discharge In Air

Siemens made the first ozone generation system by corona discharge about hundred and fifty years ago. At present mainly two types of atmospheric pressure electrical discharges - corona discharge and dielectric barrier discharge are used for production of ozone. Another type of discharge, which can be used for this purpose, is multineedle to plate electrical discharge enhanced by the gas flow. Contrary to the conventional arrangement when the gas is flowing around the needles we studied the discharge in which the gas was pumped through the needles. Results of studies of ozone and nitrogen oxides production by DC electrical discharge in air at atmospheric pressure with a single hollow needle to plate electrode configuration enhanced by the flow of air through the needle for both polarities of the needle, different airflow rates and currents are presented in this paper.

Global synchrony in biospheric variations and influence on soil pH

Data collected from 1968 through 1997 showed a globally synchronous annual increase in soil acidity during the period June through August which was highly correlated with progressively decreasing geomagnetic field strength despite periodic local alterations in electromagnetic activity at the planetary boundary layer. Monthly determinations of soil pH for periods of one or more years at sites in Australia, South America, North America, Scotland, and Germany showed pH values to be consistently and significantly correlated with the monthly average geomagnetic field strength and the auroral electrojet values recorded during the time period covered by the data. Unweighed simple and multiple least squares linear regressions of soil pH on geomagnetic D, H, and Z, and the auroral electrojet gave r2 and p values as high as r2 = 0.9997, p = 0.0000. These relationships were subject to modifications in soil pH by telluric currents and electromagnetic events, such as thunderstorms and accompanying acid rain, occurring at the planetary boundary layer. Short-term variations in electrical conductivity of soil, in situ plant-available soil moisture, availability of soil mineral nutrient elements for plant uptake, soil pH, and the pH of fresh and stored samples of soil diluted 1:5 in water, rainwater, and other solutions, and Rn levels in soil and air were highly correlated with ambient telluric currents and with atmospheric electrical discharges. Decreasing soil pH values were consistently associated with decreased availability of soil mineral nutrients for plant uptake, lower foliar mineral element content in growing plants, and reduced health status, fertility, and productivity of herbivores. Rising pH values were accompanied by increases in available soil mineral nutrient elements and improvements in plant and animal health and productivity.

Long laser spark for controlling the trajectory of an atmospheric electric discharge

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text M. F. Borisov, V. M. Gromovenko, V. A. Lapshin, Yu. A. Rezunkov, V. P. Savel'eva, and V. V. Stepanov, "Long laser spark for controlling the trajectory of an atmospheric electric discharge," J. Opt. Technol. 66, 203- (1999) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

On the Magnetospheric Effects of Experimental Ground Explosions Observed from AUREOL-3.

A new analysis is described for the published data from the MASSA active experiments held in 1981-1983 in the USSR. These tests were aimed to simulate earthquake effects in the magnetosphere and ionosphere using surface chemical explosions. Measurements in the magnetosphere above the explosions were made from the AUREOL-3 satellite (Galperin et al., 1985a, 1985b). ELF/VLF noises were excited within an altitude range from 410 km to ≈ 2000 km along the Explosion plasma Flux Tube (EFT), based on the E-region above the explosion point (L ≈ 1.5). During the MASSA-1 experiment, at L ≈ 1.3, before the EFT crossing, 5 minutes after the explosion at L = 1.5, a strong upward moving MHD-impulse was registered with a sharp front. The front was accompanied by excited ion sound waves. Indirect arguments are presented for the origin of the impulse within the EFT, its bouncing and accompanied cross-L drift to, and then trapping at L = 1.3. The effects observed suggest the existence of a natural MHD-impulse generator and/or its power amplifier located in the middle atmosphere not higher than 70 km. It generates/amplifies the electromagnetic response in the magnetosphere and ionosphere. It is suggested that the form of electric discharges in the middle atmosphere known as “red sprites” or “blue jets” can serve the role of the natural generator/power amplifier for the effects in the ionosphere and magnetosphere observed in the MASSA experiments. If real, it can be speculated, that similar “amplification” effects through atmospheric electrical discharges could play a role in the generation of some earthquake precursor effects observed in the magnetosphere and ionosphere.

Dynamics of OH (X2 Pi , v=0) in high-energy atmospheric pressure electrical pulsed discharge

Time transients of the number density of the hydroxyl radical ground state X2 Pi (v=0) formed in the DC high-energy atmospheric pressure pulsed discharge were measured by means of laser-induced fluorescence. The frequency doubled dye laser was tuned to the A2 Sigma from X2 Pi (v'=1 from v"=0) transition at 282 nm while emission at 309 nm from A2 Sigma to X2 Pi (v'=0 to v"=0) band, was observed. The discharge peak current Imax varied from 10-2 to 10 A, and the time duration was from 500 ns to 50 mu s. The discharge was operated at repetition rate of 10 Hz. The population of v"=0 of OH reaches the steady state within the first 20 mu s of the discharge and its value is independent on the current for Imax>or=0.2 A. The significant build-up of v"=0 state population was observed after the discharge pulse. The hydroxyl ground state number density reaches its maximum value approximately 100 mu s after the discharge and is up to three times larger than during the discharge pulse. This increase of v"=0 population is attributed to the vibrational relaxation within X2 Pi state.

Medical geochemistry of nitrates and human cancer in Sri Lanka

A study of the incidence of various types of human cancer in relation to nitrate concentrations in Sri Lanka revealed a significant positive correlation for stomach, small intestine, oesophagus and liver cancers, as well as total malignant cancer incidence and benign tumours. The Northern and Western Provinces of Sri Lanka showed the highest total cancer rate. The abundance of nitrates in the groundwater of certain provinces of Sri Lanka has been attributed to use of nitrogeneous fertilizers, human and animal wastes in densely populated regions and nitrates produced as result of atmospheric electric discharges and precipitation. Even though the correlation of nitrate abundance and cancer rates is significant, nitrate cannot necessarily be considered as being causative in view of the biological intricacies involved in the complicated mechanism of cancer inducement.

Gaseous products created by electrical discharges in the atmosphere and condensation nuclei resulting from gaseous phase reactions

Our study has a double aim. Firstly, to study the production of NO, NO x, O 3 and condensation nuclei by electrical discharges. Secondly, to attempt to make an estimation of the natural production for the whole earth of these products by atmospheric discharges. We deal firstly with atmospheric electrical discharges which are simulated in a point-to-plane discharge vessel in which we can alter the mean current, the point polarity and the relative humidity (R.H.). We used natural or bottled air or bottled nitrogen with a constant gas flow of 55 f h −1. We noted that the production of O 3 takes place mainly during predischarge regimes, whilst spark discharges are mainly productive of NO and NO x. Condensation nuclei (C.N.) seem to be produced by gaseous phase reactions between NO x and O 3 and depend on R.H. Secondly, we calculate the global production of these species by atmospheric electrical discharges. For the NO x we take account of our experimental results and of the hypothesis used elsewhere by Chameides et al. (1977) and for the O 3 Griffing's hypothesis (1977) as well as thunderstorm statistics given by Schonland (1953). Our estimation for NO x is of 25Tgy −1 and for O 3 our calculations give a lower limit of about 90Tgy −1 which seems to indicate that production of O 3 by atmospheric electrical discharges (corona or point discharges and lightning) is more important than usually assumed. In the actual state of the measurements, it seems unreasonable to attempt to give an estimation of production of the C.N. Complementary experiments with bottled nitrogen seem to indicate that atomic oxygen and OH radicals do not play an initial role in C.N. creation. Our results lead us to believe that these C.N. may be HNO 3 products.

Nitrogen economy of endolithic microbial communities in hot and cold deserts

The source of combined nitrogen in endolithic microbial communities was studied in samples from desert localities in North and South America, the Middle East, South Africa, and Antarctica. Nitrogen fixation (acetylene reduction) seems to occur only exceptionally. Evidence suggests that, in general, the nitrogen source for endolithic microorganisms in deserts is abiotically fixed nitrogen produced by atmospheric electric discharges (lightning or aurorae), conveyed to the rock by atmospheric precipitation. Nitrogen is apparently not a limiting factor in these low-productivity communities. An incomplete nitrogen cycle seems to be present which includes the following pathways: supply of nitrates and ammonia from the atmosphere; decomposition of organic matter to ammonia; reassimilation of ammonia; ammonia volatilization; loss of organic matter through weathering (only in certain Antarctic rocks); biological nitrogen fixation (exceptional).

A plasma wave investigation for the Voyager Mission

The Voyager Plasma Wave System (PWS) will provide the first direct information on wave-particle interactions and their effects at the outer planets. The data will give answers to fundamental questions on the dynamics of the Jupiter and Saturn magnetospheres and the properties of the distant interplanetary medium. Basic planetary dynamical processes are known to be associated with wave-particle interactions (for instance, solar wind particle heating at the bow shock, diffusion effects that allow magnetosheath plasma to populate the magnetospheres, various energization phenomena that convert thermal plasma of solar wind origin into trapped radiation, and precipitation mechanisms that limit the trapped particle populations). At Jupiter, plasma wave measurements will also lead to understanding of the key processes known to be involved in the decameter bursts such as the cooperative mechanisms that yield the intense radiation, the observed millisecond fine-structure, and the Io modulation effect. Similar phenomena should be associated with other planetary satellites or with Saturn's rings. Local diagnostic information (such as plasma densities) will be obtained from wave observations, and the PWS may detect lightning whistler evidence of atmospheric electrical discharges. The Voyager Plasma Wave System shares the 10-meter PRA antenna elements, and the signals are processed with a 16-channel spectrum analyzer, covering the range 10 Hz to 56 kHz. At selected times during the planetary encounters, the PWS broadband channel will operate with the Voyager video telemetry link to give complete electric field waveforms over the frequency range 50 Hz to 10 kHz.

Atmospheric electrical discharges in the presence of water and ice particles

A variety of electrical discharges were photographically examined in a preliminary survey of water-involving discharge phenomena that occurred in simulations of the thunderstorm environment. The investigation was limited to situations showing no clear evidence of water drop disruption. Discharges between oppositely charged falling drops of water exhibit a luminosity distribution that suggests electron emission from the negative drop. Measurements indicate that the current density in this discharge may be 20 amp/cm2 or more as is the case with metallic cathode glow discharges. It is conceivable that a comparable emission occurs in clouds whenever a positive streamer comes within 40 μ of a particle's surface, and that this emission quenches weak streamers. Photographs show weak streamers that terminate on either ice or water surfaces, and stronger streamers and sparks that glide over the surface of a water drop. These latter observations demonstrate that in the arclike discharge produced by an intense spark, a water surface does not supply charge as copiously as a metallic one. Positive streamers are attracted to water and ice particles, which facilitates charge transfer across the air-water interface whether it occurs by ion capture or by electron emission. Since long sparks are often preceded by streamers, the paths of sparks in an atmosphere containing water or ice particles should be modified by charges deposited on the particles by the streamers. Paths were observed in several situations involving 50- to 70-cm-long impulsive sparks and target volumes nonuniformly populated with either fog droplets or with falling cloudburst densities of 2-mm-diameter drops. Effects on the paths were slight, and they could be detected only statistically; but in all situations there was, if anything, a slight tendency for the sparks to avoid wet regions of the target volume. Just the opposite tendency was found in a situation involving 2-cm-long sparks and a much denser distribution of drops. The assorted observations are related by citation to various published discussions of the lightning path, the rain gush, the transfer of charge from precipitation elements to the lightning channel, and the radio noise from clouds.

Ion-Molecule Reactions

E W McDaniel, V Cermak, A Dalgarno, E E Ferguson and L Friedman Chichester: Wiley 1970 pp vii + 359 £9.50 The experimental and theoretical study of ion–molecule reactions has greatly intensified in the last few years and it is now one of the most active fields in atomic and molecular physics. This is mainly due to the fact that a deep understanding of ion–molecule reactions is essential to our better comprehension of upper atmospheric phenomena, radiation chemistry, flames, electrical discharges and many other phenomena of fundamental importance.

IEE Electronics Division: Chairman's address. Radio and weather

Radio and the weather are intimately connected: from this stems the interdisciplinary subject of radio-meterorology. Out of the study of the effects of the weather on radio wave propagation, radio techniques for meterorological research and applications are evolved. Some consideration is given in the paper to the relationship between atmospheric electrical discharges (lightning) and associated radio phenomena, but the emphasis is mainly on the interaction between the troposphere, with its constituents, and very short radio waves. The importance of radiometerorological research to the development of space and terrestrial communication is discussed, and also the relevance of such research to a better appreciation of the dynamical processes in the lower atmosphere.

Laboratory ball lightning

A mechanism for the formation of ball lightning is discussed. It is suggested that the presence of a low density of simple hydrocarbons in the atmosphere, coupled with an atmospheric electrical discharge, may be sufficient to form the phenomenon. A simple calculation establishes a theoretical diameter of approximately 6–130 cm. A laboratory experiment is described in which a ball of fire was formed. The phenomenon appeared to possess many properties of natural ball lightning, including existence for a finite time without an external energy source.