scholarly journals Experimental Investigation of a Magnetically Balanced Arc in a Transverse Argon Flow

1966 ◽  
Vol 88 (1) ◽  
pp. 27-30 ◽  
Author(s):  
T. W. Myers ◽  
C. N. McKinnon ◽  
J. C. Lysen
Keyword(s):  
Magnetic Field ◽  
Experimental Study ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Electric Arc ◽  
Test Apparatus ◽  
Gas Velocity ◽  
Argon Gas ◽  
Argon Flow ◽  
Arc Current

An experimental study of an electric arc in crossed convective and magnetic fields has been made. An electric arc was established across a rectangular test section through which argon gas was flowing at approximately atmospheric pressure and velocities up to 100 m/sec. Magnetic field strengths up to 3 webers/m2, oriented so that the Lorentz force opposed the convective force on the arc, were applied perpendicular to both the arc and the direction of the argon gas flow. The test apparatus and the procedure used to obtain the experimental relationship between the velocity of the argon flow and the balancing magnetic field are described. An analysis which assumed the magnetically balanced arc to be a gaseous cylinder positioned between the electrodes and with a diameter varying directly as the arc current satisfactorily explained the observed dependence of the balancing magnetic field on the gas velocity.

Effects of External Transverse Alternating Magnetic Field on the Oscillating Amplitude of Atmospheric Pressure Plasma Arc

2010 ◽  
Vol 129-131 ◽  
pp. 692-696
Author(s):  
Jian Bing Meng ◽  
Xiao Juan Dong ◽  
Chang Ning Ma
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Flow Rate ◽  
Gas Flow ◽  
Atmospheric Pressure Plasma ◽  
Alternating Magnetic Field ◽  
Magnetic Flux Density ◽  
Plasma Arc ◽  
Arc Current

A mathematical model was developed to describe the oscillating amplitude of the plasma arc injected transverse to an external transverse alternating magnetic field. The characteristic of plasma arc under the external transverse alternating magnetic field imposed perpendicular to the plasma current was discussed. The effect of processing parameters, such as flow rate of working gas, arc current, magnetic flux density and the standoff from the nozzle to the workpiece, on the oscillation of plasma arc were also analyzed. The results show that it is feasible to adjust the shape of the plasma arc by the transverse alternating magnetic field, which expands the region of plasma arc thermal treatment upon the workpiece. Furthermore, the oscillating amplitude of plasma arc decreases with decrease of the magnetic flux density. Under the same magnetic flux density, more gas flow rate, more arc current, and less standoff cause the oscillating amplitude to decrease. The researches have provided a deeper understanding of adjusting of plasma arc characteristics.

scholarly journals The influence of argon gas flow in the killing of staphylococcus epidermidis bacteria

2018 ◽  
Vol 16 (36) ◽  
pp. 134-139
Author(s):  
Ahmed Mahmoud Shihab
Keyword(s):  
Staphylococcus Epidermidis ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Biotechnological Applications ◽  
Plasma System ◽  
Argon Gas ◽  
Killing Rate ◽  
Normal Atmospheric Pressure ◽  
Non Thermal Plasma

In this research, non-thermal plasma system of argon gas is designed to work at normal atmospheric pressure and suitable for work in medical and biotechnological applications. This technique is applied in the treatment of the Staphylococcus epidermidis bacteria and show the role of the flow rate of Argon gas on the killing rate of bacteria, and it obtained a 100 % killing rate during the time of 5 minutes at the flow Argon gas of 5 liters/ min.

Plasma Spraying Using Ar-He-H2 Gas Mixtures

1998 ◽  
Author(s):  
S. Janisson ◽  
A. Vardelle ◽  
J.F. Coudert ◽  
B. Pateyron ◽  
P. Fauchais ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Gas Flow ◽  
Plasma Jet ◽  
Gas Mixtures ◽  
Gas Velocity ◽  
Gas Flow Rate ◽  
Static Behavior ◽  
Operating Variables ◽  
Arc Current ◽  
Plasma Guns

Abstract In D.C. plasma guns used for plasma spraying, the properties of the plasma forming-gas control, to a great extent, the characteristics of the plasma jet and the momentum, heat and mass transfer to the particles injected in the flow. This paper deals with mixtures of argon, helium and hydrogen and the effect of the volume composition of these mixtures on the dynamic and static behavior of the plasma jet. Both were investigated from the measurements of arc voltage and gas velocity. Correlations between these parameters and the operating variables (arc current, gas flow rate, gas mixture composition) were established from a dimensional analysis. The results were supported by the calculation of the thermodynamic and transport properties of the ternary gas mixtures used in this study.

scholarly journals The effect of the liquid layer thickness on the evaporation intensity

2018 ◽  
Vol 194 ◽  
pp. 01030
Author(s):  
Aleksei Kreta ◽  
Vyacheslav Maksimov
Keyword(s):  
Experimental Study ◽  
Layer Thickness ◽  
Liquid Layer ◽  
Flow Rate ◽  
Gas Flow ◽  
Shear Stresses ◽  
Gas Velocity ◽  
Evaporation Intensity ◽  
Liquid Layer Thickness ◽  
Thermocapillary Forces

An experimental study of the influence of thermo-capillary forces and shear stresses with the side of the gas flow to the evaporation flow rate has been made. The experiments were carried out at various thicknesses of the liquid layer and constant gas velocity. The influence of the thickness of the liquid layer on the evaporation flow rate (the intensity of evaporation) has been analyzed. It is shown that the thermocapillary forces have a direct effect on the evaporation flow rate of the liquid layer.

Dynamic Measurements on a Pulsed Short Arc Driven by a Magnetic Field

1973 ◽  
Vol 51 (14) ◽  
pp. 1499-1504 ◽  
Author(s):  
Michel G. Drouet ◽  
Rosario Beaudet
Keyword(s):  
Magnetic Field ◽  
Atmospheric Pressure ◽  
Streak Camera ◽  
Transverse Magnetic ◽  
Temporary Increase ◽  
Dynamic Measurements ◽  
Current Step ◽  
Arc Voltage ◽  
Arc Current ◽  
Short Arc

Current and voltage measurements were performed on a short (3 mm) arc burning at atmospheric pressure in air and driven (100–200 ms−1) along two rail electrodes by a transverse magnetic field. The arc current was pulsed from a steady state value of 40 A to 200–1000 A in < 10 μs. Simultaneous measurements revealed the arc voltage to be constant. On the contrary, a stationary arc, subjected to the same current step, showed a simultaneous temporary increase of the arc voltage of 10–40 V. To facilitate the interpretation of the results, the motion of the arc was recorded using a fast streak camera. It was found that, after applying the current step, the velocity of the arc does not change instantaneously, but that the luminous plasma expands in the wake of the arc. An interpretation of the results is proposed; it is based on the assumption that in a moving arc, the distributions of the current and the conductance are not similar.

scholarly journals Correlation of radius of cathode spot of vacuum arc of metals on the size of generated droplets

2021 ◽  
Vol 66 (4) ◽  
pp. 391-398
Author(s):  
G. V. Markov ◽  
A. T. Volochko ◽  
V. G. Zaleski ◽  
N. Yu. Melnik
Keyword(s):  
Experimental Study ◽  
Cathode Spot ◽  
Simple Relation ◽  
Electric Arc ◽  
Vacuum Arc ◽  
Alloy Droplet ◽  
Spot Radius ◽  
Droplet Sizes ◽  
Arc Current ◽  
Pure Metals

The simple relation to estimate the cathode spot radius of a vacuum arc of pure metals is obtained. On its basis, is established between the cathode spot radius and the size of droplets generated by the cathode spot a correlation. This enables to find ways to reduce droplets in the plasma flow, which forms coatings by the vacuum electric arc method. The paper presents the results of experimental study of the droplet sizes depending on the vacuum arc current iд. The size and amount of the droplets on an area of 1 mm2 of the coating surface are determined using the ImageSP program. As the initial data, the microstructures of the coatings are used with an increase of: ç100, ç200, ç500, ç1000, ç1500. The droplets have been generated by a cathode spot of a vacuum arc for the alloy of the composition, at.%: 68Al–8Cr–4Nb–20Si. It is established that the number of droplets with a diameter of < 2 μm is generated most of all, and the number of droplets with a diameter > 10 μm is generated least of all. The number of generated droplets with a diameter from 2 to 10 μm slightly depends on the arc current iд. It is noted that the diameter of the alloy droplet is smaller than the diameter of the droplets generated by the cathode spot on its components due to the fact that the radius of the cathode spot on the alloy is smaller than the radius of the cathode spot on its pure components.

CORRELATION BETWEEN MICROSTRUCTURE AND YIELD STRESS IN MAGNETICALLY STABILIZED FLUIDIZED BEDS

2010 ◽  
Vol 02 (03n04) ◽  
pp. 185-198
Author(s):  
J. M. VALVERDE ◽  
M. J. ESPIN ◽  
M. A. S. QUINTANILLA ◽  
A. CASTELLANOS
Keyword(s):  
Magnetic Field ◽  
Tensile Strength ◽  
Gas Flow ◽  
Fine Particles ◽  
Contact Forces ◽  
Interparticle Contact ◽  
Gas Velocity ◽  
Jamming Transition ◽  
Interparticle Contacts ◽  
Different Response

A magnetofluidized bed consists of a bed of magnetizable particles subjected to a gas flow in the presence of an externally applied magnetic field. In the absence of magnetic field, there is a given gas velocity at which naturally cohesive fine particles can form a network of permanent interparticle contacts capable of sustaining small stresses. This gas velocity marks the jamming transition of the fluidized bed. For gas velocities above the jamming transition, the bed resembles a liquid. Below the jamming transition, the bed behaves as a weak solid and it has a nonvanishing tensile strength. In the absence of magnetic field, the tensile strength of the solidlike stabilized bed has its only origin in nonmagnetic attractive forces acting between particles. In the presence of a magnetic field, the gas velocity at the jamming transition and the tensile strength of the bed depend on the field strength as a consequence of the magnetostatic attraction induced between the magnetized particles. In this work we present experimental measurements on the jamming transition and tensile strength of magnetofluidized beds of linearly magnetizable fine powders. It is shown that powders with similar magnetic susceptibility but different strength of the nonmagnetic forces show a different response to the magnetic field. This finding can be explained by the influence of the nonmagnetic natural forces on the network of contacts. Thus, our experimental results reported in this paper reinforce the role of short-ranged interparticle contact forces on the behavior of the system, which contrasts with the usual modeling approach in which the magnetofluidized bed is viewed as a continuum medium and a fundamental assumption is that the fields can be averaged over large distances as compared with particle size.

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