High Frequency Electric Discharge Research Articles

Comprehensive Study on the Cutting Force Modeling and Machinability of High Frequency Electrical Discharge Assisted Milling Process Using a Novel Tool

Comprehensive Study on the Cutting Force Modeling and Machinability of High Frequency Electrical Discharge Assisted Milling Process Using a Novel Tool

Reaction-Diffusion Modeling to Assess what Limits Effective Acetylcholine Fluctuations at High Frequency Cholinergic Electroplaques

In the weakly electric fish Eigenmannia (glass knifefish), high frequency (200-550Hz) electric organ discharge (EOD) is driven by high frequency cholinergic synaptic input onto the electrocytes at their electroplaques. Evolutionarily, this system derives from skeletal muscle endplate synapses. We are interested in what, physically, limits the rapidity with which acetylcholine (ACh) concentrations can oscillate to successfully activate post-synaptic ACh receptors (AChR) and thereby trigger EODs at the oscillating frequency. Assuming periodic release of ACh into a 50nm wide cylindrical synaptic gap, we solve numerically a one dimensional reaction-diffusion model at 200Hz and 500Hz. The model included the diffusion of ACh and its interactions with AChesterase (AChE) and AChRs. For ACh released periodically at the two frequencies, we vary the ratio of ACh input to the AChE concentration. The biochemical/biophysical characteristics of AChE/ACh and AChR/ACh are those typical of neuromuscular junctions. The AChR can be in four states: closed (AR), with one or two bound ACh molecules (AR1 and AR2) and finally open state (AR2open). At 500Hz a higher AChE/ACh ratio is needed to remove ACh from the cleft between consecutive ACh releases. Only a small fraction of the ACh molecules reaches the AChRs, and there are residual amounts of ACh molecules from the preceding release. Previous computational studies showed that the persistently present ACh should not impede high frequency electrocyte firing, provided the cholinergic current is subthreshold for triggering firing. In our simulations, the fast AChE-ACh reactions (not AChR-ACh kinetics) limit the upper frequency for triggering electrocyte action potentials. We suggest, therefore, that carry-over (persistent) activation of AChRs could account for the observed upper limit for EOD frequency in Eigenmannia individuals.

High frequency electric discharge between jet and solid electrodes

The types and forms of combustion of electric discharges of high-frequency (HF) current with liquid and solid electrodes at atmospheric pressure are investigated. The discharge emission spectrum, plasma composition, electron concentration, and temperature of the heavy component are studied. Thermograms on the surface of liquid and solid electrodes during the combustion of the discharge are investigated.

Ball lightning passage through a glass without breaking it

In long history of ball lightning (BL) theory development there is a struggle of two concepts. According to the first one, BL – is a high frequency electrical discharge, burning in the air due to action of alternating electric field or a continuous current generated by an external source of energy. According to the second one, the BL is a material body, storing energy within itself. Data banks of BL observations give evidence that BL can pass through glasses, leaving no traces on them. Supporters of the first concept consider this as the proof of the correctness of the “electric field” BL nature. Representation of BL as a material body with internal source of energy explains most of its features, but has difficulties in explanation of BL penetration through glasses. We describe results of research of the glass, through which BL freely passed, that was observed by one of the authors. They proved the presence of traces left by BL. With a help of optical and scanning microscopes and laser beam probing of the glass, that experienced action of 20cm BL, we have found traces in it: in the glass we found a region of 1–2mm, at the center of which a cavity of 0.24mm diameter is located. This gives evidence to a “material” nature of BL. BL possibility to pass through small holes and its ability to “make” such holes poses a number of difficult issues to researchers indicated in the article.

Particle image velocimetry analysis of the flow around circular cylinder induced by arc discharge rotating in magnetic field

An experimental study of the flow around a circular cylinder model with magnetohydrodynamic (MHD) actuator was carried out in subsonic wind tunnels (M < 0.2). Combined (high frequency and pulsed-periodic) electrical discharge was used in this MHD actuator. This intense pulsed-periodic discharge had the following characteristics: voltage amplitude up to 15 kV, current amplitude up to 16 A and frequency up to 1 kHz. Permanent magnets with an induction of B = 0.1 T on the model surface were placed inside the cylindrical model. Annular electrodes were situated on the surface of the cylindrical model. The Lorentz force causes the rotation of the electric arc on the model surface. In turn, the movement of the arc discharge induces the rotation of the gas near the surface of the model. In this experiment were carried out the measurement of the flow velocity profile near the surface of the model on the following operational modes: with plasma and without plasma. A parametric study of the aerodynamic performance of the model was fulfilled with respect to the discharge parameters and the flow velocity. To measure the velocity profile was used particle image velocimetry method.

Magnetite Nanoparticles Prepared By Spark Erosion

Abstract In the present research, we study a possibility of using the electric spark erosion method as an alternative to the method of chemical co-precipitation for preparation of magnetic nanoparticles. Initiation of high frequency electric discharge between coarse iron particles under a layer of distilled water allows obtaining pure magnetite nanoparticles.

Modeling the Oscillating Dipole Properties of Electric Organ Discharge in the Weakly Electric Fish, Eigenmannia

One of the most studied weakly electric fish, Eigenmannia produces a continuous high frequency electric organ discharge (EOD) used to sense nearby objects and communicate with conspecifics. The EOD of an individual fish has a characteristic frequency (within the species range, 250-600 Hz) which it shifts when necessary to avoid jamming. The nearly dipolar oscillating electric field yields zero net current and is generated by parallel columns of identical, synchronously discharging electrocyte cells. Recent findings from whole fish respirometry (during high-frequency signaling over a range of frequencies) have renewed interest in the frequency-dependent energetics of the EODs (Lewis et al 2014 J Neurosci 34:197) but the modeling based on past analyses is missing some key features of the in-vivo electrolyte operation. We have constructed a model for the neurally-driven electrocyte action potentials (APs) that underlie the EOD. APs are initiated by brief post-synaptic cation influxes through AChR channels at each electrocyte's innervated posterior end. This yields a head positive current while the anterior end serves mainly as a capacitor whose discharge yields the head negative current of the oscillating dipole cycle. To maintain the appropriate [Na]in and [K]out levels, Na/K-ATPase pumps run continuously. Modeling the activity of this ATP consuming protein gives us access to electrocyte energetics and frequency-dependent EOD efficiency. Modeling the posterior-anterior current flows gives us access to the electric field patterns produced by the electrocytes.

Electrical discharges with liquid electrodes used in water decontamination

The results of experimental investigation of the DC electrical discharge with moving air bubbles in the electrolyte, as well as of high frequency electrical discharge with a diaphragm membrane, within a wide parameter range are presented. We investigated active component formation and enhancement of the wastewater decontamination by means of production of a disinfecting agent with a maximal content of the electrical discharge products (copper and silver ions and hydrogen peroxide).

Solar powered high voltage energization for vehicular exhaust cleaning: A step towards possible retrofitting in vehicles

This paper proposes a novel way of generating high voltage for electric discharge plasma in controlling NO x emission in diesel engine exhaust. A solar powered high frequency electric discharge topology has been suggested that will improve the size and specific energy density required when compared to the traditional repetitive pulse or 50 Hz AC energization. This methodology has been designed, fabricated and experimentally verified by conducting studies on real diesel engine exhaust.

Synthesis of nanopowders under high frequency electric discharge assisted mechanical milling

Electric discharge assisted mechanical milling can be applied to the synthesis of a range of fine powder products, including nanocrystalline agglomerates and individual nanoparticles and nanofragments. Processing variables include: starting powder sample size; electric arc parameters such as arc length and arc voltage/current; mechanical milling parameters; gas atmosphere and ionized gas species present. We describe results of an initial experimental program underway to investigate phase transformations and/or particle fragmentation during discharge milling using a new pulsed power supply working at frequencies in the kHz range. The aims were to determine processing parameters required for the synthesis of potentially useful high surface area particles, nanostructural powders and nanoparticles and to compare products with those synthesised by Hz frequency discharge milling. Microstructural, morphological and phase changes induced by kHz discharge milling were characterised by X-ray diffractommetry and transmission electron microscopy. Results were found to depend on the often competing processes of fragmentation into nanoparticles, agglomeration of powder particles, particle melting and/or sintering and chemical reaction induced by mechano-processing in the presence of a particular type of plasma. Discharge milling of graphite under Ar/4% H 2 resulted in a range of products including: graphite nanostructures, carbon nanotubes and other exotic nanofragments. It was found that, compared with processing at 50 Hz, high frequency (kHz) electric discharge assisted mechanical milling of graphite resulted in higher yields of carbon nanofragments. Discharge milling of hematite resulted in partial reduction to magnetite and FeO and the formation of nanostructural oxide nanorods and nanorod clusters. Discharge milling of Co–WC resulted in products including: micron and submicron fracture products, nanostructural regions of Co and WC and carbon rich nanorods.

Nanotube and Nanorod Synthesis under High Frequency Electric Discharge Assisted Mechanical Milling

Electric discharge assisted mechanical milling using a 50 Hz power supply has been used to produce a range of fine and nanostructural products, including nanocrystalline aglomerates and individual nano-particles and nano-fragments. Processing variables include; starting powder sample size; electric arc parameters such as arc length and arc voltage/current; mechanical milling parameters; gas atmosphere and ionized gas species present. We describe results of an experimental program underway to investigate phase transformations and/or particle fragmentation during discharge milling using a new pulsed power supply working at frequencies in the kHz range. The aims of this preliminary investigation were to determine processing parameters required for the synthesis of potentially useful high surface area particles, nanostructural powders and nanoparticles, and to compare products with those synthesised by Hz frequency discharge milling. Microstructural, morphological, and phase changes induced by kHz discharge milling were characterised by x-ray diffractommetry and transmission electron microscopy. Results were found to depend on the often competing processes of fragmentation into nano-particles, agglomeration of powder particles, particle melting and/or sintering, and chemical reaction induced by mechanoprocessing in the presence of a particular type of plasma. Discharge milling of graphite under Ar/4%H2 resulted in a range of products including; graphite nanostructures, carbon nanotubes and other exotic nanofragments. It was found that, compared with processing at 50 Hz, high frequency (kHz) electric discharge assisted mechanical milling of graphite resulted in higher yields of carbon nanotubes. hematite resulted in partial reduction to magnetite and FeO,and the formation of nanostructural oxide nanorods and nanorod clusters. Discharge milling of Co-WC resulted in products including; micron and submicron fracture products, nanostructural regions of Co and WC, and carbon rich nanorods and nanotubes.

Design considerations for a CCFL and its surroundings

Abstract— A TFT‐LCD module includes a backlight unit, which normally uses one or more thin cold‐cathode fluorescent lamps (CCFLs). Since a CCFL is driven at high frequency and high voltage, there is a leakage current. In recent years, TFT‐LCD modules have been getting thinner, with a wider screen size and a narrower frame; consequently, the leakage current has come to have a significant influence on the design of the LCD module and the dc/ac inverter unit that generates the high‐voltage ac to drive the CCFL. It is actually impossible to probe the inside of a working CCFL because of the high voltage, high frequency, and low electric discharge current. This fact adds to the difficulty of the analysis and the design. This paper proposes an electrical model of a CCFL and a simulation method using the model, making it possible to analyze the inside of the CCFL and to provide some important parameters that are required for the basic design of the LCD module and the dc/ac inverter, before the construction and measurement of actual samples.

Coupled Electron and Molecular Vibrational Kinetics in a 1D Particle-in- Cell Model of a Low Pressure, High Frequency Electric Discharge in Nitrogen

The interaction between state-to-state vibrational and charged particle kinetics in a low-pressure, high frequency electric discharge in N 2 is investigated by using a PIC-MCC (Particle-in-Cell with Monte-Carlo collisions) model assuming a one-dimensional bounded system, while the vibrational kinetics is introduced by solving a set of reaction and diffusion equations. The catalytic activity of the electrode surfaces is considered in the boundary conditions. The coupling of the two kinetics has an effect on the Electron Energy Distribution Function (EEDF) and consequently on the rate of vibrational and electronic excitation of N 2 molecules, the charged particle distribution and the electric field.

A quantitative assay of biologically important compounds in simulated primitive earth experiments

A CH 4- N 2- H 2 O v gas mixture was subjected to a high voltage (20 kV), high frequency (0.3 MHz) electric discharge. The energy input in the electric discharge was varied from 0.016 to 3.048 MJ·mol −1. The chemical yields ( G), expressed as the number of molecules formed or destroyed per 100 eV of energy input were calculated for several products. The G values calculated at the lowest energy input were (- CH 4) = 6.48; (- N 2) = 2.51; ( C 2 H 2) = 1.16; ( HCN) = 0.215; ( CH 3 CHO) = 0.115; ( CH 3 CH 2 CHO) = 0.00161; ( CH 3( CH 2) 2 CHO) = 0.0165; (( CH 2 CO 2 H) 2) = 0.0000339; ( CH 4 → Solid material) = 0.196; ( N 2 → Solid material) = 0.00355. This is the first report in prebiotic studies in which the G values of various products in electric discharge experiments are determined. This type of study is needed in order to get a better insight into the relative role of electric discharges on the primitive Earth.

Inter-male aggressive signals in weakly electric fish are modulated by monoamines.

Apteronotus leptorhynchus is a gymnotid fish producing a constant high frequency electric organ discharge (EOD). Males of this species use transient increases in EOD frequency (chirps) as aggressive signals. They will also shift the frequency of their EOD away from the similar frequency of a nearby conspecific in order to protect their ability to electrolocate (jamming avoidance response, JAR). Monoamines have been implicated as modulatory agents for various sensorimotor and affective systems, including aggressive behaviour. Since these monoamines are present in the brain of this fish (unpublished observation), we have used these simple and quantifiable behaviours to study the role of monoamines, with special emphasis on possible specific effects on aggressive signalling (chirps). When serotonin (0.1 microgram) is injected directly into the ventricle of these fish it briefly inhibits chirping (aggression) without inhibiting the JAR; this is consistent with the hypothesis that, in mammals, serotonin inhibits aggressive behaviour. Noradrenaline (0.1 microgram) enhances both chirping and the JAR. Dopamine (0.1 microgram) enhances the JAR; it has powerful but inconsistent effects on chirping (inhibition or excitation).

Radiation- and plasma-induced radical formation in fluorochlorocarbons and reactions with semiconductor materials

Non-thermal energy (ionizing radiation, high frequency electrical discharge) generates halogen atoms from halocarbons which react readily with adjacent solid materials. The mechanism and extent of such processes depend on the physical state of the systems, the method by which the energy is applied and the chemical properties of the compounds used. We have studied the formation of hydrolyzable inorganic halides irradiating C 2F 3Cl 3 (with Co-60 gamma radiation) in the presence of small arsenic particles as well as gallium spheres. The results may be interpreted by a heterogenous scavenger action, but a least with gallium a radiationinduced direct surface reaction has to be included. Under the influence of a high frequency plasma discharge CF 2Cl 2 gas reacts at low pressure with GaAs. The removal of GaAs from a whafer and the yields of hydrolyzable inorganic halides were measured at various power densities and with admixture of oxygen. The results are describable with a kinetic model, if a plasmachemical yield, defined similar to the G-value of radiation chemistry, is introduced. Thus the common features which originate from the chemical nature of the halocarbons recognizable.

Plasma anodization as a dry low temperature technique for oxide film growth on silicon substrates

The anodization of silicon substrates in an oxygen plasma is promising as a low temperature and dry process for growing a native oxide film on this substrate. The oxygen plasma can be generated by either a high frequency electric discharge or a d.c. electric discharge. An experimental set-up for the anodization will be described. One advantage of this process is a fast oxidation rate, depending on the substrate temperature and the anodization current. In order to grow on a silicon substrate an SiO 2 film of thickness about 10 4 Å within 1 h, the substrate should be mounted near the plasma-generating region where the substrate temperature will reach about 600 °C, which is still sufficiently low to prevent the redistribution of impurities in the substrate. Using isotopic oxygen 18O 2 we monitored the transport of oxidants through the oxide during the anodization of silicon. During this process both silicon ions and oxygen ions drift across the oxide. This, together with the low substrate temperature, prevents the generation of stacking faults in the substrate. The dielectric and chemical properties of plasma-anodic SiO 2 are the same as those of thermally grown SiO 2, but the density of the interface trap states between the plasma-anodic SiO 2 and the silicon substrate is higher by one order of magnitude than that in the thermally grown SiO 2/Si system, although the high density of the interface states can be reduced by annealing in forming gas or in an ambient containing chlorine. One advantage of the anodic oxidation of silicon substrates in an oxygen plasma is the low rate of lateral oxidation under the mask. Very small bird's-beak-shaped structures were observed in the selective oxidation of silicon using a sputtered aluminium oxide film as a masking material against oxidation.

Epitaxy of GaN by means of a nitrogen stream activated by a high frequency electrical field discharge

Epitaxy of GaN by means of a nitrogen stream activated by a high frequency electrical field discharge

Taste reception in the Mediterranean fruit fly: Electrophysiological and behavioural studies

The effect of various salts and sugars on the taste receptors of Mediterranean fruit fly females was studied by recording electrical discharge of stimulated labellar sensilla, proboscis extension, food consumption, and survival. Contact of a stimulating sugar solution with the tip of one sense hair is sufficient to cause proboscis extension. Stimulation by either sugars or salts results in an immediate high frequency electrical discharge; adaptation is rapid during the first 3 to 5 sec. Among sugars the highest frequency was recorded with sucrose, fructose, or glucose. Stimulation was less marked with galactose, d-arabinose, and maltose, whereas a low response was elicited by mannose and l-arabinose. There was no response to lactose. Of the two sugar alcohols tested, inositol was stimulatory whereas mannitol was not. Dominant activity of one cell receptor was recorded in response to the more stimulatory sugars. With the other sugars, a mixed response of more than one cell was evident. Consumption and survival was generally positively correlated to electrical response to the sugars; there were, however, a few exceptions, e.g. some consumption of lactose and mannitol, with the latter being utilized, and high mortality in d-arabinose and inositol-fed flies. Consumption of sucrose—on a dry weight basis—rose with increase in its concentration, but the volume of the ingested solution decreased. A significant electrical response of a single cell was recorded following stimulation by sodium and potassium chloride. Divalent cations were less stimulatory. An inhibitory effect of calcium on the sugar receptor was demonstrated.

Préparation et purification d'actinomycine‐D‐3H par une méthode spécifique

AbstractActinomycine‐D has been tritiated by exposure to tritium gas. Among the various conditions tested the use of a catalyst made of palladium deposited on alumina, and of an amount of tritium gas corresponding to a gas pressure of 20 torrs and to a radioactivity of 2 Ci for 5 mg of actinomycine results in the highest specific radioactivity of about 200 mCi/mM. The activation of the tritium gas by a high frequency electric discharge increases the specific radioactivity only in the absence of the catalyst. The purification of the labelled actinomycine is achieved by formation of a complex with D N A. This complex carries a labelled by‐product which is subsequently separated by thin layer chromatography.