Types Of Electrical Discharges Research Articles

Simultaneous dry reforming and desulfurization of biomethane with non-equilibrium electric discharge at ambient temperature

We investigated two types of electrical discharges for converting biomethane into syngas at ambient temperature and atmospheric pressure. Low energy pulsed discharge (LEP) has a good property for this reaction and it could convert biomethane into syngas and also H 2S was converted into solid sulfur simultaneously. This is due to the high electron energy of LEP, and the electron has enough energy to dissociate C–C bond and C–S bond. On the other hand, dielectric barrier discharge could convert H 2S into solid sulfur, but methane and CO 2 in the biomethane were not reacted at lower input power. Our investigation showed that proper choice of electric discharge could bring selective reaction for dry reforming of biomethane and desulfurization, and this was due to the correlation between the bond dissociation energy of each molecule and electron energy level of each discharge.

Nitrogen Fixation By Corona Discharge On The Early Precambrian Earth

We report the first experimental study of nitrogen fixation by corona discharge on the anoxic primitive Earth. The energy yields of nitric oxide (NO) and nitrous oxide (N(2)O) were experimentally determined over a wide range of CO(2)-N(2) mixtures simulating the evolution of the Earth's atmosphere during the Hadean and Archean eras (from 4.5 ba to 2.5 ba). NO, the principal form of fixed nitrogen in lightning and coronal discharge in early Earth, is produced ten times less efficiently in the latter type of electrical discharge with an estimated maximum annual production rate of the order of 10(10) g yr(-1). For N(2)O the maximum production rate was estimated to be approximately 10(9) g yr(-1). These low rates of syntheses indicate that corona discharges as point discharges on the clouds and ground did not play a significant role in the overall pool of reactive nitrogen needed for the emergence and sustainability of life.

Coloring Europa with Impacts

PLANETARY SCIENCE The Galileo spacecraft sent home stunning images of Europa. Its water-ice surface was covered with arcuate cracks, finely to coarsely hachured areas, chaotic terrains, and, perhaps most dramatically, more colors than expected for an icy body. Some of the brown-yellow ice patches may be due to contamination of the water-ice surface by solid organic macromolecules. Laboratory experiments have shown that macromolecules can be produced in gas mixtures and on ices by energetic reactions with carbon, nitrogen, and water. Borucki et al. considered possible sources of energy on Europa and tested the possibility that hypervelocity impacts of small meteors are involved by performing shock wave experiments on ice. Three types of electrical discharges occurred in their experiments: a short-duration pulse associated with the impact; a longer, secondary pulse associated with the propagation of cracks after impact; and a short, tertiary pulse associated with plasma-like reactions. All three types could supply enough energy to create organic macromolecules in Europan ice. — LR J. Geophys. Res. 10.1029/2002JE001841 (2002).

Parameters of an Electric Discharge in Electrolytes and Physicochemical Processes in an Electrolyte Plasma

The parameters of an atmospheric-pressure electric discharge across an active metal electrode immersed in an electrolyte and the electrolyte surface (the thickness of the plasma sheath produced around the active electrode, the distribution of electric potential in the sheath, electrolyte temperature near the sheath boundary and electrode surface) were measured, and the plasma parameters (electric field strength, mean energy and number density of electrons) were determined. It was shown that the plasma of these atmospheric-pressure discharges is nonequilibrium and the discharge in electrolytes is a new type of electric discharge.

New spectroscopic observations in electric discharges through carbon monoxide

Two types of electric discharges were used: (a) In a supersonic expansion of pure CO gas. (b) In a U-shaped tube immersed in liquid nitrogen where either pure CO or mixtures of CO+He, CO+Ne, CO+NO are introduced. In both cases, the analyzed emissions were exclusively those issuing from the negative glows of the discharges. Fourier Transform spectra were recorded in the 28 000–17 000 cm −1 visible spectral region and also in the 8000–2000 cm −1 infra-red interval. Comparison of the two sets of spectra showed that spectra (a) correspond to excitation of the primary species whereas spectra (b) result from excitation of final compounds produced in the positive column. In the latter case, the main new observations are: (i) Selective excitation of particular upper state vibrational levels in the E 3 Σ −–a 3 Π Herman system. (ii) Appearance of the C 1Σ +– B 1Σ + (0,0) Rydberg–Rydberg infrared band whereas the associated optical C 1Σ +– A 1Π Herzberg transition is absent. (iii) “Anomalous” vibrational distribution in the ground state vibration–rotation spectra. All the above observations are concomitant with previously reported IR emissions involving very high rotational levels (up to J=120) in the ground state. To explain them, processes involving dissociative recombinations of dimer cations are suggested.

Pulsed plasma processing of organic compounds in aqueous solution

Non-thermal plasma processing using a pulsed electrical discharge has been investigated as an alternative method for the degradation of organic compounds contained in water. The active species produced by the electrical discharge may play an important role in degrading organic compounds in water. Three types of electrical discharge formed by the needle-plate electrode system were used in this investigation. The degradation of phenol by electrical discharge with the effects of the addition of gas bubbling and chemicals on degradation efficiency was investigated. The results showed that the degradation rate of phenol was affected by electrical discharge types and oxygen gas bubbling. The addition of a small amount of hydrogen peroxide greatly increased the degradation rate of phenol, in which the ultraviolet light from discharge plasma was considered to be a cause of effective degradation.

Production of nitrogen oxides by lightning and coronae discharges in simulated early Earth, Venus and Mars environments.

We present measurements for the production of nitrogen oxides (NO and N2O) in CO2-N2 mixtures that simulate different stages of the evolution of the atmospheres of the Earth, Venus and Mars. The nitrogen fixation rates by two different types of electrical discharges, namely lightning and coronae, were studied over a wide range in CO2 and N2 mixing ratios. Nitric oxide (NO) is formed with a maximum energy yield estimated to be ~1.3 x 10(16) molecule J-1 at 80% CO2 and ~1.3 x 10(14) molecule J-1 at 50% CO2 for lightning and coronae discharges, respectively. Nitrous oxide (N2O) is only formed by coronae discharge with a maximum energy yield estimated to be ~1.2 x 10(13) molecule J-1 at 50% CO2. The pronounced difference in NO production in lightning and coronae discharges and the lack of formation of N2O in lightning indicate that the physics and chemistry involved in nitrogen fixation differs substantially in these two forms of electric energy.

Nonequilibrium Plasma Treatment of Miscible Polystyrene/Poly(phenylene oxide) Blends

Oxidative low-pressure and atmospheric plasma modification of polystyrene/poly(2,6-dimethyl-1,4-phenylene oxide) miscible polymer blend surfaces has been studied using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The extent and stability of surface oxygenation is found to be critically dependent upon both the type of electrical discharge employed and the bulk polymer blend composition.

Physical investigations of a high-current vacuum arc discharge

The experimental data on the processes at the electrodes and in the interelectrode gap of a high-current vacuum arc discharge that were accumulated by different researchers are systematized. A critical analysis is conducted on the essentially static discharge models proposed earlier. A dynamic model of a two-component plasma is described and substantiated, which, in the opinion of the authors, better explains the current results of experimental studies into this type of electric discharge than the static models.

Computer simulation of microwave and DC plasmas: comparative characterisation of plasmas

Self-consistent calculations of the parameters of self-sustained MIP and DCP in argon and in model gases in the diffusion-controlled regime have been carried out. The calculated parameters of argon microwave produced plasmas (MIP) and direct current plasmas (DCP) are in satisfactory agreement with experimental data. The use of the proposed invariant group of parameters, namely specific absorbed power Pd, plasma gas pressure p, discharge tube radius R and tube wall temperature TW, for the comparisons of different types of electrical discharges have been grounded. The results of calculations in argon using different models of discharge and the results of calculations in model gas plasmas are given.

Rigorous results on a time-dependent inhomogeneous coulomb gas problem

We report results obtained by rigorous analysis of a nonlinear differential equation for the electron density n e in a specific type of electrical discharge. The problem is essentially two-dimensional. We discuss in particular (i) the escape of electrons to infinity above a critical temperature; and (ii) the boundary layer exhibited by n e near zero temperature.

Multipacting mechanism as the origin of breakdown in high-frequency electrical discharges in gases

The mechanism by which gas at low pressure breaks down when subjected to a high-frequency electrical field is considerably different from that of other types of electrical discharge. Provided the pressure is sufficiently low, the breakdown electric field strength is independent of the kind of gas, depending instead on the type, condition and separation of electrode surfaces, and the frequency of alternation of the electric field. The multipacting mechanism as developed by several authors is summarized and brought together in a single framework.

An Induction-Coupled Radio-Frequency Source for Emission Spectroscopy in the Vacuum Ultraviolet

Various types of electrical discharges have been used as emission sources for the vacuum ultraviolet region, but few reports have been made of induction-coupled radio-frequency discharge sources. Plato used an electrodeless ring discharge for excitation of argon line spectra in the vacuum uv. More recently, Kirkbright, Ward, and West were able to determine sulfur and phosphorus quantitatively in the vacuum uv with a high frequency plasma torch. An induction-coupled radio-frequency discharge through static argon at atmospheric pressure and its application for emission spectroscopy in the vacuum uv region are described.

VENTRICULAR FIBRILLATION DURING SELECTIVE ANGIOCARDIOGRAPHY.

Adequate grounding of an electromechanical injector does not exclude the delivery of an electrical shock to a patient during injection of contrast substance. Seven episodes of ventricular fibrillation which occurred during cineangiocardiography indicated the possibility that they were produced by an electrical transient. Several power injectors were tested and all produced the same type of electrical discharge. A simple circuit which will eliminate the electrical discharge can help to reduce the risk of electromechanical injection.

On the Function and Evolution of Electric Organs in Fish

ABSTRACTThe electric discharges of Gymnarchus niloticus and of representative species of seven genera of the Mormyridae have been examined in their natural habitat in Africa and in the laboratory. Comparable investigations of the South American Gymnotidae have shown the existence of two discharge types in both these unrelated fish families. The first type of electric discharge consists of very regular sequences of continuously emitted, monophasic pulses, varying from species to species in frequency, and within narrower limits from individual to individual. Fish emitting this first type of pulses include Gymnarchus, Hypopomus and Eigenmannia. The frequency range for these fish lies between 60 and 400 discharges/sec. The frequency does not alter with the state of excitation of the fish. The duration of individual pulses is relatively long, i.e. 2–10 msec. The second type of discharge is less regular in frequency, the pulse duration much shorter and the pulse shape more complex. The individual discharge from the whole electric organ lasts about 0.2 msec, in Petrocephalus. This type of discharge is found in all the examined species of the Mormyridae and in such forms as Gymnotus carapo and Staetogenes elegans. The basic discharge rate of a resting mormyrid is somewhat variable and not strictly rhythmical. It usually lies between 1 and 6 pulses/sec. Stimuli which excite the mormyrids cause an increase in the discharge frequency. The recorded maximum is about 130 pulses/sec. Suitable stimuli can inhibit the discharges of the Mormyridae for prolonged periods. In Gymnotus carapo and Staetogenes elegans the basic discharge rate is higher and of regular rhythmicity. Depending on temperature the frequencies lie between 30 and 87 pulses/sec. When these fish are excited the frequencies are increased up to 200 pulses/sec, for a short time. The shape of the electric field, which is set up with each pulse around the fish, has been examined. A theory has been proposed which suggests that these fish, by means of their electric pulses, can locate objects if their electrical conductivity differs from that of water. These fish have shown themselves extremely sensitive to influences affecting the electric field. This has been studied by applying artificial electric stimuli, by studying the effects of conductors and non-conductors introduced into the field, and the reactions towards magnetic fields and electrostatic charges. Conditioned reflex experiments with Gymnarchus niloticus and Gymnotus carapo have shown that these fish can detect the presence of a stationary magnet, and that they can discriminate between conductors and non-conductors. The prey of these fish does not appear to be affected by the discharges. Inter alia, the electric pulses have a social significance. This locating mechanism may be considered as an adaptation to life in turbid water. Gymnotidae and Mormyridae (taken to include Gymnarchus) show striking features of convergent evolution. Unusual locomotory adaptations such as swimming by means of the dorsal fin (Gymnarchus), the anal fin (Gymnotidae) and ‘Gemminger‘s bones’ (Mormyridae) may be considered as a means which tends to make the axis of symmetry of the fish and of its electric field coincide during active movements. A new theory for the evolution of electric organs has been suggested. A major prerequisite appears to be a receptor sensitive to electrical stimulation. It is suggested that special sensory and nervous differentiations of the lateralis system (‘mormyromasts’, valvulae cerebelli) are concerned with the perception and integration of electric stimuli. Muscular action potentials have been recorded in the water at some distance from non-electric fish. The easiest explanation for the evolution of strong electric organs would appear to start from such muscular action potentials, and proceed via weak electric organs used for orientation, to the powerful offensive and defensive electric organs."

Experiments with gas-filled triodes

In this paper experiments are described showing the different types of electrical discharges in a gas-filled triode. The determining parameters are the following: the cathode emission, the spacing of cathode, grid and anode, the diameter of the meshes of the grid, the potentials of the grid and the anode, the gas pressure and the differential ionization function of the gas. The anode voltage may be concentrated in a space charge sheath. If this space charge sheath is located at the grid, the anode current may be modulated with moderate, grid potentials. If not, much larger voltages are required for modulation.

Electric Discharges in Gases-II Ions in Dense Gases

This article is a review of some of the established facts and accepted theories pertaining to the behavior of ions in dense gases, supplementing the article that appeared in last month's issue reviewing current knowledge concerning ionization and excitation, and preparing the way for next month's article which will discuss various types of electric discharges in the light of the basic processes set forth in this and the preceding article. This is the fourth of a series of special articles developed under the sponsorship of the A.I.E.E. committee on education, and the second of three devoted to the major divisions of the general subject of electric discharges in gases. Full details concerning this series of articles are given on p. 238 of ELECTRICAL ENGINEERING for February 1934. -Editor.

Electric discharges in gases — II: Ions in dense gases

This article is a review of some of the established facts and accepted theories pertaining to the behavior of ions in dense gases, supplementing the article that appeared in last month's issue reviewing current knowledge concerning ionization and excitation, and preparing the way for next month's article which will discuss various types of electric discharges in the light of the basic processes set forth in this and the preceding article. This is the fourth of a series of special articles developed under the sponsorship of the A.I.E.E. committee on education, and the second of three devoted to the major divisions of the general subject of electric discharges in gases. Full details concerning this series of articles are given on p. 238 of ELECTRICAL ENGINEERING for February 1934.