Discharge Current Value Research Articles

STRUCTURE AND PROPERTIES OF GLOW DISCHARGE IN ARGON WITH HOLLOW CATHODE

This paper deals with studying into the modes of burning and structure of the glow discharge with a hollow cathode and a flat anode in argon. We have demonstrated that the electron beam usually leaving the cathode cavity in a high voltage (glow mode) disappears when the anode approaches the edge of the hollow cathode. In this case the discharge is burning only on the outer surface of the cathode plates forming the cavity. The anode motion does not affect essentially the properties of the discharge burning in the hollow mode. We have obtained the axial intensity profiles of the emission lines of argon atoms and ions in the hollow and glow modes for various gas pressure and discharge current values. We have also shown that the brightest lines correspond to the transitions from 3p54p to 3p54s levels. The lines corresponding to the transitions from higher levels as well as the emission lines of argon ions possess a rather low intensity.

Floating potential calculation for a Langmuir probe in electronegative plasmas and experimental validation in a glow discharge

A radial Langmuir probe sheath model is used to make a prediction of the floating potential of a Langmuir probe immersed in an electronegative plasma. The new electronegative plasma sheath model takes into account the positive ion and the negative ion thermal energies and is valid for any ion temperature value. The values predicted can be used for diagnosing and controlling an electronegative plasma, and we compare them with measurements of the floating potential in an Argon plasma and in a Neon plasma with with two distinct electron populations at different temperatures. We have found that the agreement is very good in a wide range of plasma pressure and discharge current values, and thus the model is applicable for electronegative plasmas. Moreover, the model can be used to measure the energy with which the ions will collide with the surface of the probe.

Comparing properties of dc discharges in tubes possessing a hollow cathode or anode in an undergraduate laboratory

In this paper, we suggest a simple experiment to study the properties of a dc glow discharge in tubes with a ‘hollow cathode and flat anode’ and a ‘hollow anode and flat cathode’ design in the course of undergraduate laboratory work devoted to the research into the characteristics of gas discharges. The work is aimed at observing a phenomenon where employing the tube with a hollow cathode furnishes a much larger discharge current than one can get with a hollow anode design or that with both flat electrodes. Within the certain pressure range (27–40 Pa under our conditions) two negative glows overlap at the center of the cavity resulting in a considerable (several times) increase in the discharge current. The anode shape does not practically affect the discharge current value that is manifested by the fact that current–voltage characteristics for both flat electrodes and the hollow anode design almost coincide.

Wide-frequency band measurement and analysis of electrochemical noise of Li/MnO2 primary battery

The electrochemical noise of a commercially produced Li/MnO2 primary battery was measured during discharge via a constant value resistor. Power spectral density frequency dependences were calculated for different state of charge values across the frequency band from 0.02 to 5 kHz. It was shown that they possess close to linear frequency dependences. For high state of charge values, an intersection with the thermal noise spectrum was observed in a high-frequency band. The electrochemical impedance of the investigated type of battery was measured at different charge values both during discharge and following a relaxation pause. Impedance spectra obtained under load conditions were used to model the electrochemical noise spectra. It was shown that impedance parameters can be used to describe the electrochemical noise spectra in the frequency band above 500 Hz at state of charge values higher than 50%. Dependencies of electrochemical noise amplitude on discharge current value were investigated at different states of charge. It was shown that power spectral density has a linear dependency on discharge current at a power of about 2 for a charged battery and 2.5 for a discharged battery.

Effects of Discharge Current and Target Thickness in Dc-Magnetron Sputtering on Grain Size of Copper Deposited Samples

A study of the effects of the discharge (sputtering) currents (60-75 mA) and the thickness of copper target (0.037, 0.055 and 0.085 mm) on the prepared samples was performed. These samples were deposited with pure copper on a glass substrate using dc magnetron sputtering with a magnetic flux density of 150 gauss at the center. The effects of these two parameters were studied on the height, diameter, and size of the deposition copper grains as well as the roughness of surface samples using atomic force microscopy (AFM).The results of this study showed that it is possible to control the specifications of copper grains by changing the discharge currents and the thickness of the target material. The increase in discharge current values ​​led to a decrease in height copper grain's values ​​of 20% at a current of 75 mA and target thickness of 0.085 mm. Furthermore, the increasing in the current caused a decrease in the diameter and size values of deposition copper grains. Finally, the surface roughness of the samples was reduced by a 15% by changing the current and target material thickness at 75 mA and 0.085mm respectively.

Optical and electrical analysis of multi-electrode cylindrical dielectric barrier discharge (DBD) plasma reactor

Aiming to decrease the dielectric barrier discharge (DBD) capacitive current, a new type of multi-electrode cylindrical DBD plasma reactor was proposed in this work. Due to the novel multi-electrode design, the discharge current peak value of the newly designed plasma reactor decreased by 66.24%, from 16.26 mA for the traditional device to 5.49 mA. Besides, the number of the micro-discharges was found almost 2 times higher than that of the traditional device, indicating the generating of more discharge channels (from 37 to 89). The enhanced corona discharge formed at the electrode edges caused by fringe effect was considered as the main reason. The opti-electrical analysis was performed using multi-electrode plasma reactors with different electrode configurations. The changes of optical emission efficiency (Ieff), equivalent capacitance of dielectric layer (Cd) and the discharge gap (Cg) were investigated under different applied voltage, discharge length, interval between adjacent outer electrodes and electrode width. The experimental results indicated the efficient discharge length l and fringe effect were responsible for the variations of Ieff, Cd and Cg. Higher applied voltage resulted in a higher Ieff, but higher current at the same time. Besides, Cd gradually increased along with the increased applied voltage while Cg presented the decreased trend. Ieff increased along with the enhanced fringe effect caused by the shorter electrode width and smaller interval between adjacent outer electrodes, while decreased with the increased discharge length. Cd and Cg decreased with increased interval between outer electrodes, but increased with the enhanced discharge length and electrode width. The voltage distribution analysis indicated that the change of Ieff was mainly due to the change of the voltage across the gas gap Vg. This work can give a deeper and further understanding on the discharge characteristics of the proposed multi-electrode plasma reactor.

Passive/Active BTMS For EV Lithium-Ion Batteries

This work is about a thermal management system of prismatic lithium-ion batteries for electric vehicles (EV) and hybrid vehicles. Solid state thermoelectric modules (TEMs) were installed on a heat spreader specially designed to mechanically support the prismatic li-ion battery cells. TEMs offer many advantages to vehicular application, being environmentally friendly, quiet, having a low weight, and well suited for heating or cooling the battery cells. The proposed system was modeled and simulated. After its construction, it was tested under different values of discharge current and ambient temperature values corresponding to various driving conditions of the vehicle. In addition, its performance was compared with a compatible forced air cooling system. Experimental results show the feasibility of the proposed thermal management system as it consumes very little parasitic power when ambient temperature falls within the range of 0–40 °C]. However, its design added 120% to the volume of the battery pack and 80% to its weight. This additional weight consumes 2 Wh/Km from the EV batteries.

Optimization of electrical discharge machining AA6061/ 10 %Al2O3 composite using Taguchi optimization technique

In the present study, the stir casting set up was used to fabricate AMMC. For this purpose stir casting set up was fabricated. The influence of the most relevant parameters of Electrical Discharge Machining over material removal rate, tool wear rate of a aluminium metal matrix composite material (AMMC) has been carried out. The material used in this study is aluminium matrix composite in which AA 6061 is reinforced with 10 % Al2O3 particles. The AMMC composite was machined using 27 copper tools with Ø = 10 mm. Different pulse on-times (Ton), discharge current values (I) and duty factor(D.F) was used for each electrode. For the experiments, Taguchi L27 orthogonal array design was used. The AA 6061/10 % Al2O3 composite material can easily be machined by EDM and maximum MRR, minimum TWR can be obtained by controlling the machining parameters. Analysis of Variance (ANOVA) is employed to determine the significance of input variables on the desired performance measures.

Simulation, Design, Construction of Duoplasmatron and Diagnostic Neutral Beam System for Alborz Tokamak

Diagnostic Neutral Beam (DNB) has been used for measuring plasma parameters of tokamaks such as ion and electron temperature, safety factor, impurity concentration and etc. Ion source and electrical power supply specification are the main part of DNB. Arc discharge current value is affected by filament current and anode voltage. Beam current changes with arc current signal in our experiment that agree with theoretical relations. Sixty milli-ampere (60 mA) pulse beam current is because of arc current of about 40 A and extraction voltage of about 20 kV. The increase of beam current with arc current has been reported experimentally and effect of arc current on beam current has been investigated for several high extraction voltages. Optimum condition, which means having a telescopic beam (minimum divergence) for specific parameters of duoplasmatron, has been simulated and verified with experimental test. The best extraction voltage for these parameters has been found to be about 16-kV. The ratio of the perpendicular velocity to parallel velocity has been calculated to be about 0.012. It has been shown experimentally with optical emission spectroscopy that increase in arc current and magnetic current increase proton content of beam.

Simulation study on transient electric shock characteristics of human body under high voltage ac transmission lines

Human body under high-voltage AC transmission lines will produce a certain induced voltage due to the electrostatic induction. When the human body contacts with some grounded objects, the charges transfer from the body to the ground and produce contact current which may cause transient electric shock. Using CDEGS and ATP/EMTP, the paper proposes a method for quantitatively calculating the transient electric shock characteristics. It calculates the human body voltage, discharge current and discharge energy under certain 500kV compact-type transmission lines and predicts the corresponding human feelings. The results show that the average root value of discharge current is less than 10mA when the human body is under the 500kV compact-type transmission lines and the human body is overall safe if the transmission lines satisfy the relevant design specifications. It concludes that the electric field strength above the ground should be limited to 4kV/m through the residential area for the purpose of reducing the electromagnetic impact.

Basic Characteristics of In-Liquid Plasma Jet and Electrode Damage

The most progress towards a practical method of fusing municipal waste incineration ash has been in the use of a plasma jet that employs arc discharge, a form of thermal plasma. However, a remaining problem is that stable plasma generation is prevented by melting of the nozzle of the plasma-jet torch by the high-temperature plasma flow. With the objective of developing high-speed fusion treatment for waste materials using an in-liquid plasma jet, basic research was conducted on plasma stability and the durability of plasma-jet torches, including electrodes and nozzles. Basic plasma jet characteristics such as the discharge voltage, current, and power value at the time of plasma jet generation were investigated experimentally. The relationship between the temperature distribution near the tip of a plasma jet torch and electrode damage was investigated by fluid-heat coupled analysis using the finite element method.

Conducting wall Hall thrusters in magnetic shielding and standard configurations

Traditional Hall thrusters are fitted with boron nitride dielectric discharge channels that confine the plasma discharge. Wall properties have significant effects on the performances and stability of the thrusters. In magnetically shielded thrusters, interactions between the plasma and the walls are greatly reduced, and the potential drop responsible for ion acceleration is situated outside the channel. This opens the way to the utilization of alternative materials for the discharge channel. In this work, graphite walls are compared to BN-SiO2 walls in the 200 W magnetically shielded ISCT200-MS and the unshielded ISCT200-US Hall thrusters. The magnetically shielded thruster shows no significant change in the discharge current mean value and oscillations, while the unshielded thruster's discharge current increases by 25% and becomes noticeably less stable. The electric field profile is also investigated through laser spectroscopy, and no significant difference is recorded between the ceramic and graphite cases for the shielded thruster. The unshielded thruster, on the other hand, has its acceleration region shifted 15% of the channel length downstream. Lastly, the plume profile is measured with planar probes fitted with guard rings. Once again the material wall has little influence on the plume characteristics in the shielded thruster, while the unshielded one is significantly affected.

A Method of Generating Timing for a Given Target Current Waveform in Electromagnetic Launch Technology

Under the condition of given charging voltage, by adjusting the timing of the power supply trigger, the electromagnetic emission can produce different discharge current waveforms, and then produce different initial velocity. This paper mainly uses the characteristics of the discharge current in a single power module in electromagnetic launch, by specifying the rising time and the maximum value of the total discharge current; a multipopulation genetic algorithm is used to obtain the optimal trigger timing, and the speed control of electromagnetic launch can be achieved. The specific implementation process of algorithm are as follows: the rising time and the peak value of the expected current are set as the objective function, the timing is set as a variable, and the multiple time series are binary coded to get multiple individuals, and then calculate the degree of survival by crossover, mutation, and heredity among individuals, that is, to judge whether the rising time and the maximum value of the discharge current can reach the expected goal, and to keep the survival of the genes to the next generation and screen repeatedly, and then to select the optimal control timing. The optimal control strategy can be obtained by adjusting the parameters such as genetic algebra and mutation rate. The experimental results show that this method produces the optimal power supply timing, and through the application of digital signal processing control system, the expected discharge current waveform can be obtained in the experiment of electromagnetic launch, which also lay a good foundation for the rate control of electromagnetic launch.

Experimental and theoretical study of the radial density distribution of metastable atoms in a dc glow discharge in neon

Radial distributions of the number density of metastable atoms in the positive column of a dc glow discharge in neon were studied both experimentally and theoretically in a wide range of gas pressures (0.1–50 Torr) and discharge currents (10–40 mA, for gas pressures of 0.1–10 Torr, and 20–100 mA, for the gas pressure of 50 Torr). Measurements were performed in a glass discharge tube 4 cm in diameter using the optical absorption technique. It was found that, at pressures of 0.1–1 Torr, the radial profiles of the number density of metastable atoms are almost independent of a discharge current value. At higher pressures, noticeable narrowing of the profiles with discharge current was observed; at a pressure of 50 Torr, measurements were performed up to the jump-like transition of the positive column from the diffuse form to the constricted one. Theoretical studies of the discharge plasma parameters under experimental conditions were carried out in the framework of a one-dimensional (along the tube radius) discharge model. For the case of the diffuse form of the discharge, the results of simulations appeared to be in a reasonable agreement with the experimental data.

Estimating the Lifetime of Wireless Sensor Network Nodes through the Use of Embedded Analytical Battery Models

The operation of Wireless Sensor Networks (WSNs) is subject to multiple constraints, among which one of the most critical is available energy. Sensor nodes are typically powered by electrochemical batteries. The stored energy in battery devices is easily influenced by the operating temperature and the discharge current values. Therefore, it becomes difficult to estimate their voltage/charge behavior over time, which are relevant variables for the implementation of energy-aware policies. Nowadays, there are hardware and/or software approaches that can provide information about the battery operating conditions. However, this type of hardware-based approach increases the battery production cost, which may impair its use for sensor node implementations. The objective of this work is to propose a software-based approach to estimate both the state of charge and the voltage of batteries inWSN nodes based on the use of a temperature-dependent analytical battery model. The achieved results demonstrate the feasibility of using embedded analytical battery models to estimate the lifetime of batteries, without affecting the tasks performed by the WSN nodes.

Influence of electric discharge machining on fatigue limit of high strength aluminum alloy under finish machining

The aim of this study was to investigate the fatigue limit of the electric discharge machined aluminum alloy 2024 T6. Machining was performed at 3, 6, 9, and 12 A discharge current values while all other parameters were kept constant. The fatigue tests were performed on a four-point rotating bending machine at the frequency of 50 Hz and at ambient temperature. Fatigue limits at 107 cycles were determined using staircase (up-and-down) method and the obtained data was analyzed statistically. For reference purposes, fatigue strength of the conventionally turned specimens was also found by the same technique. The EDM surface is characterized by its morphology, roughness, hardness, and thickness of the resolidified layer. The effects of discharge current values on these surface characterizing parameters and subsequent influence on fatigue limit have been discussed.

Comparison between the 1st and 3rd order mode temporal characteristics of two-sided multipactor discharge in cavity

For investigating the influence of high order two-sided multipactor discharge on the accelerator field-building process, the temporal characteristics of the 3rd order two-sided multipactor discharge in oxygenfree copper cavity are studied numerically. The particle-in-cell and Monte-Carlo methods are used in the simulation and the characteristics of the 1st order mode are also studied for comparison. The numerical results can be concluded as follows. In the multipactor discharge evolution, the electron number, discharge current, deposited and discharge power increase exponentially and tend to be saturated. At the saturation stage of the 3rd order mode, the values of electron number, discharge current, deposited and discharge power are lower than at the saturation stage of the 1st order mode. Meanwhile, the rising time of waveform in the 3rd order mode is longer than in the 1st order mode. There is a time-delay phenomenon in the waveform of discharge current, which results in a partial charging process in multipactor discharge. The average value of the discharge power is equal to the average deposited power. The value of discharge power in the 3rd order mode is about 1% of that in the 1st order mode. Therefore, the 3rd order mode is not significant in accelerator field-building process compared with the 1st order mode. The characteristic of the 1st order two-sided multipactor discharge is the accelerated motion of single electron beam, while that of the 3rd order is the complex accelerated-decelerated-accelerated motion of multi-electron beams. When the multipactor discharge enters into the saturation stage, the space charge effect of the 3rd order mode is not stronger than that of 1st order mode.

Anion exchange membrane fuel cell modelling

ABSTRACTA parametric model predicting the performance of a solid polymer electrolyte, anion exchange membrane fuel cell (AEMFC), has been developed, in Matlab environment, based on interrelated electrical and thermal models. The electrical model proposed is developed by modelling an AEMFC open-circuit output voltage, irreversible voltage losses along with a mass balance, while the thermal model is based on the energy balance. The proposed model of the AEMFC stack estimates its dynamic behaviour, in particular the operating temperature variation for different discharge current values. The results of the theoretical fuel cell (FC) stack are reported and analysed in order to highlight the FC performance and how it varies by changing the values of some parameters such as temperature and pressure. Both the electrical and thermal FC models were validated by comparing the model results with experimental data and the results of other models found in the literature.

“Super-acceleration” of ions in a stationary plasma discharge

We report on the detection of the acceleration effect of the bulk of ions in a stationary plasma E×B discharge to energies exceeding considerably the value equivalent to the discharge voltage. We determined the conditions necessary for the generation of high-energy ions, and ascertained the influence exerted on the value of the ion energies by pressure (flow rate) and the kind of plasma-producing gas, and by the value of discharge current. The possible acceleration mechanism is suggested.

Mode Transitions in Hall-Effect Thrusters Induced by Variable Magnetic Field Strength

Mode transitions in a 6 kW laboratory Hall-effect thruster were induced by varying the magnetic field intensity while holding all other operating parameters constant. Ultrafast imaging, discharge current, and thrust measurements were used to characterize the change in discharge channel current density and thruster performance through mode transitions. The modes are described here as global oscillation mode and local oscillation mode. In global mode, the entire discharge channel is oscillating in unison and spokes are either absent or negligible with discharge current oscillation amplitude (root mean square) greater than 10% of the mean value and can even be as high as 100%. In local oscillation mode, perturbations in the discharge current density are seen to propagate in the direction. Spokes are localized oscillations that are typically 10–20% of the mean discharge current density value. The discharge current oscillation amplitude and mean values are significantly lower than global mode. The mode transitions changed with operating conditions, where the transition between global mode and local mode occurred at higher relative magnetic field strengths for higher mass flow rate or higher discharge voltage. The thrust was approximately constant through the mode transition, but the thrust-to-power ratio and anode efficiency decreased significantly in global mode. The peaks in thrust to power and anode efficiency typically occur near the transition point. Thruster performance maps should include variation in discharge current, discharge voltage, and magnetic field, known as maps, at different flow rates to identify transition regions throughout the life of a thruster. These results are used to calculate a transition surface for use by operators to keep the thruster operating in an optimal mode.