Arc Discharge Mode Research Articles

Слаботочный разряд в потоке аргона при атмосферном давлении в условиях образования атомов металлов: электрические и оптические характеристики

The paper presents the results of a study of the current-voltage characteristics and optical emission spectra of plasma of a atmospheric pressure pulsed discharge plasma at a frequency of several tens of kilohertz and a pulse duration of up to 10 μs, in the mode of generation of plasma flows containing metal particles. The features of the plasma generator conclude in combination of the design of electrodes, as well as the modes of electric and gas supply of the discharge system. The cathode is a crucible containing a melting insert which allows the discharge operation in a low-current form with a current of 40 mA to 1 A, at a sufficiently high voltage of 150 to 200 V, without transition to arc discharge mode. Such parameters make it possible to generate atomic flows of a melting cathode insert, which are blown out by a jet of working argon gas, pumped at a flow rate of 1 l/min, outside the discharge system. The entry of a metal component into a gas-discharge plasma affects the parameters of the discharge operation, as well as the properties of its optical emission. In the context of this phenomenon, the spectral distributions of the intensity of optical radiation corresponding to the lines of magnesium, indium, and zinc were investigated, as well as their time dependence during the current pulse period operation, in relation to the identification of physical features leading to stable generation of flows of metal atoms at atmospheric pressure.

Carbon Nano tube and it`s medical applications*

The carbon nanotube (CNT) represents one of the most unrivaled contrivances in the domain of new technology represented by contemporary revolution of nanotechnology. CNTs is closed to be the more important branch of nanotechnology which have been matured painstakingly meanwhile the last 20years by many investigators and different types of application papers, researches and studies around the expert because of their senior potency in various area. These tubes are rolled in the hybridization found in the grapheme type of carbon nanotubes. The paramount portions of CNTs are their nimble weightiness, small size with a high aspect ratio, pretty stretchy strength, and kindly forthright traits, which make them profitable as tautologies for various materials such polymers, metallic flatness's and earthenware. CNTs also have potential enforcements in the range of nanotechnology, medical Nano manufacture, transistors, actuators, sensors industrialization, and membranes preparation and capacitors industry. There are assorted techniques, which can be utilized for the compilation of CNTs. These implicate the arc discharge mode, chemical fumigate precipitation (CVD),the laser ablation way and the sol- gel method. CNTs can be monowalled, duplicate-walled and multi-walled. CNTs have individual mechanistic, electrified and optic qualities, commonalty of which has been extensively elaborated. The sitting article-review is converging on the composition, functionalization, differences and enforcements of CNTs. The toxic influence of CNTs is also offered in a concise form. It is clear, by the beginning of the last century, that carbon Nano-tubes (CNTs) were important in the fields of health, such as medicine and pharmacy, which had entered into system of drug delivery. The ability of these compounds attracted the interest of researchers in the fields of biomedicine and its biomedical applications such as advanced imaging, regeneration of organism tissues, drug disposal or gene delivery. There is a lot of interesting evidence about the unique advantages of nanotubes that confirm their effectiveness compared to their negative effects. © 2018 JASET, International Scholars and Researchers Association

Effect of Gas Dynamics on Discharge Modes and Plasma Chemistry in Rotating Gliding Arc Reactor

This article investigates the effect of gas flow rate on arc discharge mode and plasma chemistry in a nonmagnetic rotating gliding arc reactor. This article is conducted using oxygen as a plasma forming gas under transient (5 LPM), turbulent (25 LPM), and highly turbulent (50 LPM) flow conditions. The voltage-current (V-I) characteristics reveal discharge modes, such as glow mode under transient flow (I <; 1 A), glow-spark transition mode under turbulent flow (I <; 1 A & I ≫ 1 A), and spark mode under highly turbulent flow (I ≫ 1 A). Arc completes full rotation under transient flow, whereas it is blown off before completing full rotation under turbulent flows. The captured optical emission lines of the discharge indicate domination of excitation reactions under glow and glow-spark transition modes and domination of both the excitation and electron impact ionization reactions under spark mode. These observations reveal that the gas dynamics changes the discharge mode of the rotating arc that in turn alters the plasma chemistry, which is a positive feature to promote specific reaction pathways.

10000-Ignition-Cycle Investigation of a Hollow Cathode for 3–5-Kilowatt Hall Thruster

In this Paper a newly designed heaterless hollow cathode is studied for 10,000 ignition cycles. The current-voltage characteristics and upstream pressure of the hollow cathode are monitored during this procedure, and a destructive analysis is made after 10,000 ignition cycles. It is found that by using a high-voltage cold ignition approach and an arc discharge mode for heating the performance of this hollow cathode is stable. The anode voltage varies within 4 V during the test, and the downstream end of the emitter and that of the orificed cathode plate are chamfered slightly. The dominant reasons for the reduction of ignition erosion and for the stable performance of the device are analyzed

Managing and maximizing the output power of a triboelectric nanogenerator by controlled tip–electrode air-discharging and application for UV sensing

Using a switch has been verified as a promising strategy for managing and enhancing the output performances of a triboelectric nanogenerator (TENG). How to design a switch without external triggering is still a challenge. Here, a self-powered air discharge switch with a tip-plate configuration is developed, in which the switch's on/off state is controlled by the voltage of the TENG itself. The electric output of the TENG can be enhanced and modulated by changing the tip-plate distance of the switch. Compared with the same TENG without a switch, the instantaneous power peak and the total output energy on a load resistance lower than 2MΩ are increased by 1600 times and 31 times, respectively, as the switch works in an arc discharge mode. It is found that the UV light can change the switch from an arc discharge mode to a corona discharge mode, which increases the equivalent resistance of the switch and decreases the output current of the TENG. The current ratio of this UV detector reaches 18.6, and the lowest detectable light intensity is 26.2 μW/cm2. Using air discharge switch is a promising route for managing TENG's output power and developing active self-powered UV sensor.

Effects of Arc Discharge Mode on the Efficiency of Biogas Reforming in an AC-Pulsed Arc Plasma System

The effects of arc discharge mode on biogas reforming performance in an AC-pulsed arc plasma system were investigated for different pulse rising times. The discharge mode changed from the re-strike arc mode to constant arc discharge mode on increasing the pulse rising time from 2 to 5 μs at a fixed discharge power. The length of the arc column periodically changed under re-strike mode, while the arc column was always longer under constant arc mode. The production yield of synthesis gas and the energy efficiency significantly improved when the arc discharge was operated under constant arc mode. The conversion rates of CH4 and CO2 increased from 15 to 80 and 12 to 27%, respectively. Under constant arc mode, the production yield of synthesis gas was 6.5 times higher than that under re-strike arc mode. In addition, the energy cost for synthesis gas production decreased remarkably from 52 to 9 kJ/mol. This is because the biogas reforming reactions, including thermal cracking, dry reforming, and partial oxidation, proceeded effectively in an area of the arc plasma, wherein the gas could react in the high-enthalpy region for a duration sufficient to ensure efficient reforming reactions. Therefore, the arc discharge mode significantly affected the chemical reactions and energy efficiency of biogas reforming.

Analysis of Energy Deposition on Ion Source Components of EAST Neutral Beam Injector

Neutral beam injection is one of the main auxiliary heating methods in controllable nuclear fusion experiments. During the operation of the EAST neutral beam injector, a large amount of energy is deposited on the ion source components, especially the electron dump (ED). In this paper, the energy deposited on the ion source components was analyzed in arc discharge mode and beam extraction mode indirectly by calculating the energy taken away by the cooling water. The results show that the ED has a large heat load: the average power density is almost 4.5 MW/m2 when the beam power is 3.3 MW. This research may lay the foundation for increasing the heat transfer capacity and guide the optimization of the ion source components in future work.

Interaction between plasma and the channel surface in a multichannel hollow cathode

A physical-mathematical model of the erosion of a multichannel hollow cathode operating in the arc-discharge mode with inert gas flow is developed. The processes of evaporation, sputtering, and recycling of the cathode material are considered. The dependence of the erosion rate on the discharge parameters is studied. Estimates for integrated and local erosion of the cathode are obtained. The calculation results satisfactorily agree with the experiment.

Correlation Between Emission, Electric, and Flow Properties of Arc-Filament Plasma Actuators

Renewed interest in flow-control devices using various forms of plasmas has motivated the design and systematic investigation of localized arc-filament plasma actuators. This newly constructed system creates electric arcs by generating electric fields in the range of between two pin-type electrodes. The potential of the actuator to influence surrounding quiescent air when placed in a cavity was investigated using emission imaging, particle image velocimetry, and current and voltage measurements. The emission imaging showed both temporal and spatial variation. The emission was most intense and variable in the first microsecond after breakdown. The particle-image-velocimetry data were acquired for several plasma currents, on times, and actuation frequencies. The data showed characteristic features of a hot gas expansion from a cavity, such as rapid gas dilatation exemplified through a blast wave, and cavity refilling from postdischarge cooling. The electric measurements were correlated to their respective emission imaging and particle-image-velocimetry measurements. The plasma voltage was found to alternate between two distinct modes: high-voltage and low-voltage. From the emission imaging, it is theorized that this actually may be the plasma alternating between glow and arc discharge modes as a result of the restricted current.

Electrohydrodynamic peculiarities of corona discharge interaction with a liquid surface

This study was devoted to experimental investigations of a corona discharge over the surface of the following liquids: tap and distilled water, alcohol, glycerin, and mixtures of alcohol with water and glycerin. One of the electrodes was placed over the liquid surface, while another one was submerged in it. Three modes of discharge over the liquid surface were obtained, namely an ordinary corona, an intermediate mode, and an arc discharge mode. In these modes, a funnel-shaped deepening, jets, and scattered jets directed toward the upper electrode were observed on the liquid surface under the action of the discharge. A qualitative mode of funnel formation on the liquid surface under the influence of an ionic wind induced by a corona discharge was presented. The formation of jets and scattered jets was related to the development of Tonks-Frenkel and Rayleigh instabilities.

Effect of a floating electrode on an atmospheric-pressure non-thermal arc discharge

Characteristics of the atmospheric non-thermal ac arc air plasmas produced by a plasma generator with a floating electrode are investigated. The measurements show that, with the help of the surface dielectric barrier discharges between the main electrodes and the floating electrode, the ignition voltage of the non-thermal arc discharges can be reduced significantly, and an arc discharge mode can be stabilized at high gas flow rates. The measured temperatures of the non-thermal arcs are at the level of 2000–3000 K under different operating conditions.

Influence of arc duration time on the synthesis of carbon nanohorns by a gas-injected arc-in-water system: application to polymer electrolyte fuel cell electrodes

Single-walled carbon nanohorns (SWCNH) can be synthesized by a gas-injected arc-in-water (GI-AIW) method at low cost. This study revealed the influence of arc discharge duration time on the yield of SWCNH in the synthesis using this method. As a result, the yield of SWCNH increased with the arc discharge duration time, while an increase in arc plasma temperature was observed. This result can be explained by considering that the increased temperature of the reaction zone can lead to an increase in carbon radical density, which can positively affect the production yield. Here, two arc discharge modes, continuous and discrete, were generated so that modes having different temperatures with the same discharge current could be compared. From this investigation, it was suggested that an excessive ion density may cause a decrease in SWCNH production. The as-grown SWCNH possessed a high specific surface area when the arc discharge current was optimized with continuous arc mode using the GI-AIW method. Such a product can support Pt catalyst with high dispersivity, leading to high performance in polymer electrolyte fuel cells as catalyst layers.

A Micromachined Robust Planar Triggered Sparkgap Switch for High Power Pulse Applications

High voltage (HV) switches capable of operating at high speeds with high current levels are used in a variety of applications in commercial and government systems. Examples of HV switches include triggered sparkgap, dielectric breakdown, and mercury vapor switches. The triggered sparkgap switch is a three-element, gas-filled, ceramic-to-metal, hermetically sealed, pressurized switch that operates in an arc discharge mode. Triggered sparkgaps have been in use for many years, providing precision timing and activation of in-flight functions such as missile stage separation. These applications involve the activation of electro-explosive devices such as an exploding bridge-wire [EBW] or an exploding foil initiator [EFI]. This paper discusses the fabrication and characterization of a novel high voltage planar discharge switch using micromachining techniques. The switch provides a low cost alternative to conventional triggered sparkgaps. The switch is designed for direct integration into the strip-line geometries used in a conventional capacitive discharge unit (CDU). The geometry of the device was selected to minimize parasitic impedances associated with conventional firing circuits. The switch design is microfabricated on an alumina substrate utilizing a patterned electron-beam deposited metallic stack. A polyimide layer selectively deposited over the metal stack provides dielectric isolation and passivation for the switch electrodes. A similar methodology was utilized to fabricate sample EFIs for switch validation tests with insensitive secondary high explosive (HE) pellets. The discharging of the HV capacitor through the patterened bridgefoil of an EFI results in rapid vaporization of the metal stack. The high pressure gas formed by the vaporized metal accelerates the adjacent polyimide layer to high velocity. The polyimde layer then impacts the HE pellet, inducing a shock wave, which results in prompt detonation of the material. Thus, this device is a type of MEMS actuator with a very specialized use. Design, fabrication and test data are presented and discussed.

Coaxial injector of a plasma opening switch operating in the nonsteady arc-discharge mode

Results are presented from interferometric studies of a coaxial injector operating in the nonsteady arc-discharge mode. The discharge was initiated and stabilized by pulsed gas puffing into the interelectrode gap of the injector. The dynamics of the plasma bunch formation and the spatial characteristics of the bunch are investigated, and the density of the generated plasma is determined.

Effect of Glow-to-Arc Transition on Loss Mechanism of Ba Atoms from Electrode of Fluorescent Lamp

The loss of Ba atoms from the electrode of a fluorescent lamp was measured while the lamp was operated in the glow and arc discharge modes at 60 Hz. A laser-induced fluorescence (LIF) technique was applied to the measurements of the temporal and spatial distributions of Ba atoms in the vicinity of the electrode. Ground-state (61S0) Ba atoms were excited to a 51P1 level by a frequency-doubled dye laser beam (350.1 nm), and the subsequent fluorescence (51P1–51D2, 582.6 nm) was detected. The temporal and spatial distributions of Ba atoms were found to be completely different in the two discharge modes. Temporally; in the arc discharge mode, the density of the Ba atoms was found to have two peaks, and the number of Ba atoms emitted in the anode half-cycle was about twofold larger than that emitted in the cathode half-cycle. In the glow discharge mode, the number of Ba atoms emitted in the anode half-cycle was found to be negligible compared with that emitted in the cathode half-cycle. Spatially; in the arc discharge mode, Ba atoms were found to be emitted mainly from the hot spot of the filament electrode. In the glow discharge mode, Ba atoms were found to be emitted from all parts of the filament electrodes homogeneously. The mechanism of Ba atom loss in both modes was discussed.

Present status of the negative ion based neutral beam injector for JT-60U

The negative ion based neutral beam injector heating system for JT-60U has contributed to core plasma heating and noninductive current drive experiments on JT-60U. For increasing further the beam power and beam pulse duration, the serious issue is improvement of source plasma nonuniformity in the ion source. Various countermeasures have been devised to solve the nonuniformity. The first is to adjust the spatial distribution of the arc discharge through regulating the arc current limiting resistors to be connected in series to each of the filament groups. The second is to change the arc discharge mode through controlling the filament temperature. These measures have been found to be very effective.

Development of Negative ION Based NBI System for JT-60U

Development for enhancing the beam characteristics in the N-NBI system for JT-60U has been continued since 1996. In order to increase beam power and duration time, a few countermeasures for improvement of source plasma non-uniformity have been tried The first is changing arc current limiting resistors for changing arc current distribution, the second is regulating filament temperature for altering arc discharge mode, the third is optimizing a magnetic barrier in arc chamber, and the fourth is blocking the beam acceleration at a strongly non-uniform source plasma area by masking both upper and lower edge of plasma grid All of these countermeasures have been confirmed to be effective.

An externally controlled, nanosecond-pulsed, Xe lamp using a high voltage semiconductor switch

We have constructed a nanosecond pulsed Xe lamp which is controllable by a small-sized, high-voltage semiconductor switch that is driven by a transistor-transistor-logic level external signal. The Xe lamp used here is commercially available and it is usually operated in a direct-current (dc) mode. The aim of the external control is to solve a discharge difficulty in a free-running Xe lamp that we have developed previously. The problem is that the free-running discharge Xe lamp suddenly switches in its operation mode from a pulsed spark-discharge mode to an undesirable, weak, dc arc-discharge mode. The pulse width of emitted light from the pulsed Xe lamp was 3.8 ns and the repetition frequency was 0.5–1 kHz with a peak power 100 W. In order to obtain an accurate timing signal required for a fluorescence-lifetime measurement system, a current probe circuit was added in the control circuit. Details of the lamp and the results of fundamental performance tests are shown.

Arc-discharge mode and interruption performance in vacuum switch tubes

Arc phenomena in vacuum switch tubes involving the transition mechanism of the arc-discharge mode, and the relations among the arc-discharge mode, the electrode material, the electrode configuration, and the interruption performance are investigated. It is suggested that the positive ion accumulation near the anode causes the anode-spot mode transition. The floating shield potential and the arc voltage are related to the interrupting ability for the arcs between unslotted flat electrodes and between spiral electrodes, respectively. Through these fundamental research activities, a new line of compact vacuum switch tubes and new types of vacuum circuit breakers carrying them have been developed. >

Electric field and electrode potential drops of arcs and glow discharges in air

A simple experimental arrangement consisting of two arcs burning in series has been devised for measurement of the voltage gradient in the discharge column. The method is based on reciprocal variation of the length of the discharges so that the total length during the measurement is constant. Experiments have been performed in the current range between 20 mA and 4 A in dry air at pressures between 20 and 150 kPa. In the arc mode the current dependence of the field can be approximated by the power function E∝Iα, where the exponent α for pressures between 60 and 150 kPa is −0.54 and slightly higher at lower pressures. The pressure dependence (at constant current) can be expressed in similar form E∝pm with the exponent m equal to 0.15 and 0.24 for currents of 1 and 4 A, respectively, and for pressures above 40 kPa. Average values of the zero-length voltage were obtained in the arc and glow discharge modes, namely, 14.5 V in the case of the arc and 367, 346, 331, and 331 V for the glow discharge at pressures of 20, 60 100, and 150 kPa, respectively.