scholarly journals MHD instability at the cathode spot as the origin of the vortex formation in high-intensity plasma arcs

2022 ◽  
Author(s):  
Hadi Barati ◽  
Hadi Barati ◽  
Abdellah Kharicha ◽  
Mohamad Al-Nasser ◽  
Daniel Kreuzer ◽  
...  
Keyword(s):  
High Intensity ◽  
Voltage Drop ◽  
Vortex Formation ◽  
Electrical Current ◽  
Arc Furnaces ◽  
Mhd Instability ◽  
Arc Shape ◽  
Magnetohydrodynamic Instability ◽  
Arc Instability ◽  
Total Voltage

Abstract Magnetohydrodynamic instability in a high-intensity arc, similar to typical arcs in DC electric arc furnaces, is simulated using an induction based model under 2D axisymmetric conditions. Time-averaged results show a good agreement with steady-state calculated results expected for a stable arc. The transient results declare that z-pinch close to the cathode, occurring due to the high electrical current density, is responsible for arc instability in this region. The unstable behavior of the arc can be evaluated in a periodic procedure. Moreover, correlations between the fluctuations in total voltage drop curve and the arc shape are investigated: when the arc is in form of column (or bell) the total voltage drop is on a minimum peak; if there is an irregular expansion of the arc in form of arms, the total voltage drop shows a maximum peak.

scholarly journals Temperature analysis of driver and optical behavior of LED lamps

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Emerson Roberto Santos ◽  
Maurício Vicente Tavares ◽  
Antonio Celso Duarte ◽  
Hélio Akira Furuya
Keyword(s):  
High Intensity ◽  
Electrical Current ◽  
Power Line ◽  
The Body ◽  
Circuit Board ◽  
Electronic Components ◽  
Low Intensity ◽  
Turn On ◽  
Flashing Light ◽  
Optical Behavior

This exploratory study was carried out with the objective to know the optical behavior of light-emitting diode (LED) lamps used and the temperature reached by electronic components that compose the driver (electronic circuit situated inside the body LED lamp) responsible to convert electrical alternating current from power line to direct current to operate the LED devices. Then, two different experiments were carried out with LED lamps. In the first experiment, 131 LED lamps used were chosen randomly and bought from household appliances store (bargain market product) presenting different nominal powers, 8, 10, 12 and 15 watts. All LED lamps were polarized at the power line at 127 V and revealed different optical behaviors, such as: not turn-on; flashing light (as strobe effect); flashing light (as strobe effect) with high intensity (more intense than normal); flashing light (as strobe effect) with low intensity (less intense than normal); fast turnon and turn-off only; and turn-on with low intensity of light (less intense than normal). The hypothesis for these behaviors can be attributed by three different behaviors: in lamps not turn-on, this failure can be attributed for dark spots that are created on the surface of LED device. In these lamps, all LED devices are electrically connected in serial. When a LED is inoperative, the electrical current is interrupted for all LED devices; damage to the electronic components caused by internal high temperature confined inside the lamp body during the operation causing electrical oscillations, as observed from different behaviors from flashing light, flashing light with high intensity, flashing light with low intensity and fast turn-on and turn-off only; swelling of the electrolytic capacitors causing low energy storage and varying the electrical current flow, the electrical current for other electronic components altered the normal optical behavior of the LED lamps. In the second experiment, the temperatures of electronic components located in driver were obtained out of body lamp revealing: from 33 (lowest temperature attributed to inductor) to 52.5ºC (highest temperature attributed to electrolytic capacitor). These temperature values represent the ideal or normal condition of operation for electronic components, but, when they are operating inside the lamp body, the found temperature values increased considerably. This characteristic can be better evidenced by strong color change (caused by accumulative temperature during the elapsed days used) on the printed circuit board used in the driver.

Arc Shape of High-Intensity Discharge Lamps: Simulation and Experiments

2014 ◽  
Vol 36 (5-6) ◽  
pp. 1327-1335 ◽  
Author(s):  
J. Schwieger ◽  
B. Baumann ◽  
M. Wolff
Keyword(s):  
High Intensity ◽  
Arc Shape

Using the total voltage drop of a stabilized DC arc to assess plasma parameters

2000 ◽  
Vol 3 (1-4) ◽  
pp. 83-88 ◽  
Author(s):  
Milovan M. Stoiljković ◽  
Ivanka Holclajtner-Antunović
Keyword(s):  
Voltage Drop ◽  
Plasma Parameters ◽  
Dc Arc ◽  
Total Voltage

scholarly journals Homogenised model for the electrical current distribution within a submerged arc furnace for silicon production

2021 ◽  
pp. 1-36
Author(s):  
ELLEN K. LUCKINS ◽  
JAMES M. OLIVER ◽  
COLIN P. PLEASE ◽  
BENJAMIN M. SLOMAN ◽  
ROBERT A. VAN GORDER
Keyword(s):  
Steady State ◽  
Electrical Current ◽  
Industrial Practice ◽  
Silicon Production ◽  
Arc Furnaces ◽  
Averaged Equations ◽  
Slow Evolution ◽  
Submerged Arc Furnace ◽  
Steady State Solutions ◽  
Submerged Arc

Silicon is produced in submerged arc furnaces which are heated by electric currents passing through the furnace. It is important to understand the distribution of heating within the furnace in order to accurately model the silicon production process, yet many existing studies neglect aspects of this current flow. In the present paper, we formulate a model that couples the electrical current to thermal, material flow and chemical processes in the furnace. We then exploit disparate timescales to homogenise the model over the timescale of the alternating current, deriving averaged equations for the slow evolution of the system. Our numerical simulations predict a minimum applied current that is required in order to obtain steady-state solutions of the homogenised model and show that for high enough applied currents, two spatially heterogeneous steady-state solutions exist, with distinct crater sizes. We show that the system evolves to the steady state with a larger crater radius and explain this behaviour in terms of the overall power balance typically found within a furnace. We find that the industrial practice of stoking furnaces increases the overall rate of material consumption in the furnace, thereby improving the efficiency of silicon production.

scholarly journals Xenopus neural crest cell migration in an applied electrical field.

1983 ◽  
Vol 97 (4) ◽  
pp. 1226-1233 ◽  
Author(s):  
R F Stump ◽  
K R Robinson
Keyword(s):  
Neural Crest ◽  
Voltage Drop ◽  
Close Contact ◽  
Neural Crest Cell ◽  
Neural Crest Cells ◽  
Electrical Current ◽  
Isolated Cells ◽  
Electrical Field ◽  
Full Complement ◽  
Applied Electrical Field

Xenopus neural crest cells migrated toward the cathode in an applied electrical field of 10 mV/mm or greater. This behavior was observed in relatively isolated cells, as well as in groups of neural crest cells; however, the velocity of directed migration usually declined when a cell made close contact with other cells. Melanocytes with a full complement of evenly distributed melanosomes did not migrate of their own accord, but could be distorted and pulled by unpigmented neural crest cells. Incompletely differentiated melanocytes and melanocytes with aggregated melanosomes displayed the same behavior as undifferentiated neural crest cells, that is, migration toward the cathode. An electrical field of 10 mV/mm corresponded to a voltage drop of less than 1 mV across the diameter of each cell; the outer epithelium of Xenopus embryos drives an endogenous transembryonic current that may produce voltage gradients of nearly this magnitude within high-resistance regions of the embryo. We, therefore, propose that electrical current produced by the skin battery present in these embryos may act as a vector to guide neural crest migration.

A simple method for volumetric measurements in isolated cardiac muscle

1979 ◽  
Vol 236 (3) ◽  
pp. H519-H524
Author(s):  
S. R. Houser ◽  
A. R. Freeman
Keyword(s):  
Cardiac Muscle ◽  
Cell Volume ◽  
Extracellular Space ◽  
Voltage Drop ◽  
Electrical Current ◽  
Experimental Chamber ◽  
Papillary Muscles ◽  
Simple Method ◽  
Disease States ◽  
Direct Electrical Current

A new method for the study of extracellular space and cell volume of cardiac muscle is described. Canine cardiac Purkinje strands and cat papillary muscles were placed within a fluid-filled aperture connecting two sides of an experimental chamber. Direct electrical current was passed through the hole, and changes in the voltage drop across it were correlated with Purkinje strand extracellular space and cell volume. The results of experiments on 21 Purkinje strands and 4 papillary muscles yielded an extracellular space of 51 +/- 2.1% (SEM) and 23.3 +/- 2.1%, respectively. When strands were superfused with hyper- (600 mosM) and hyposmotic (150 mosM) solutions, the preparations were found to attain new steady-state volumes that were 75 +/- 3.1% and 121 +/- 9% of control, respectively. This method can be used for volumetric studies in numerous cardiac muscle preparations and should be applicable to the study of volume abnormalities associated with certain disease states.

Asperity Contact Evolution: Capillarity and Electromigration Effects

2004 ◽  
Author(s):  
Ji-Hee Kim ◽  
Pil-Ryung Cha ◽  
David J. Srolovitz
Keyword(s):  
Contact Area ◽  
Electron Flux ◽  
Voltage Drop ◽  
Bulk Diffusion ◽  
Electrical Current ◽  
Asperity Contact ◽  
Atomic Transport ◽  
Atom Flux ◽  
Complete Contact ◽  
A Current

When two surfaces are brought together, contact occurs initially between asperities on the surface. If the mechanical loads are small, complete contact is never achieved and the behavior is dominated by asperity contact. The contact area and asperity morphology may evolve in time as a result of mechanical and capillarity (surface tension) effects, mediated by plastic deformation and/or diffusion. If a current passes through the contact, as in the case of micro-electro-mechanical switches, the evolution may be controlled by electromigration. This effect may be especially important if the voltage drop across the contact is fixed and the fractional contact area is small, such that the current is concentrated in a small number of contacts (see Fig. 1). Electromigration occurs as a result of the voltage driven electrons scattering off and imparting momentum to the atoms in the solid (see Fig. 2). Typically, the electromigration atom flux is opposite the direction of the electrical current (i.e., in the same direction as the electron flux). At small homologous temperatures (i.e., the temperature normalized by the melting temperature) and in small structures (such as asperities), atomic transport will be dominated by surface, rather than bulk, diffusion. In this presentation, we consider the evolution of an idealized asperity under the action of both capillarity and electromigration.

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