Anode Heat Flux Density of High-Current Arcs

1971 ◽  
Vol 93 (1) ◽  
pp. 119-123 ◽  
Author(s):  
K. T. Shih ◽  
R. Dethlefsen
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Flux Density ◽  
Heat Flux Density ◽  
Surface Melting ◽  
Gas Pressure ◽  
Anode Surface ◽  
High Current ◽  
Surface Temperatures ◽  
Arc Current

The anode heat flux density of high-current arcs was determined by measuring the time from striking an arc to the onset of surface melting. Data were taken using argon and nitrogen with different metals, pressures, and anode surface temperatures. The anode heat flux density was found to be between 104 and 106 w/cm2 for arc currents of 50 to 2000 amp; these values increased with increasing arc current and gas pressure and were higher in nitrogen than in argon. The initial anode surface temperature also had a strong effect on the anode attachment spot.

A Study of Jet Characteristics of Plasma Arc under Transverse Alternating Magnetic Field

2011 ◽  
Vol 264-265 ◽  
pp. 1222-1227
Author(s):  
Jian Bing Meng ◽  
Wen Ji Xu ◽  
Jing Sun ◽  
Xu Yue Wang ◽  
L.J. Wang
Keyword(s):  
Magnetic Field ◽  
Heat Flux ◽  
Magnetic Flux ◽  
Flux Density ◽  
Heat Flux Density ◽  
Alternating Magnetic Field ◽  
Magnetic Flux Density ◽  
Plasma Arc ◽  
Gas Flux ◽  
Arc Current

A theoretical analysis was carried out to investigate the characteristics of plasma arc injected transverse to a transverse-alternating magnetic field. Two mathematical models were developed to describe both the oscillating amplitude of the plasma arc root and the heat flux density distribution of plasma arc on the workpiece surface. 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 working gas flux, arc current, magnetic flux density and the standoff from the nozzle to the workpiece, on the oscillation and heat flux distribution of plasma arc were also analyzed. The results show that it is feasible to adjust the shape and heat flux density of the plasma arc by the transverse alternating magnetic field, which expands the region of plasma arc thermal treatment and uniforms the heat flux density upon the workpiece. Furthermore, the oscillating amplitude of plasma arc decreases, and the heat flux density gradient upon the workpiece increases with decrease of the magnetic flux density. Under the same magnetic flux density, more gas flux and more arc current cause the oscillating amplitude to decrease. The researches have provided a deeper understanding of adjusting of plasma arc characteristics.

THERMAL BEHAVIOR AND IGNITION OF HIGH-ENERGY MATERIALS CONTAINING B, ALB2, AND TIB2

2020 ◽  
Author(s):  
A. G. Korotkikh ◽  
◽  
V. A. Arkhipov ◽  
I. V. Sorokin ◽  
E. A. Selikhova ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Behavior ◽  
Flux Density ◽  
Ignition Delay ◽  
Delay Time ◽  
Heat Flux Density ◽  
Ignition Delay Time ◽  
High Energy ◽  
Energy Materials ◽  
High Energy Materials

The paper presents the results of ignition and thermal behavior for samples of high-energy materials (HEM) based on ammonium perchlorate (AP) and ammonium nitrate (AN), active binder and powders of Al, B, AlB2, and TiB2. A CO2 laser with a heat flux density range of 90-200 W/cm2 was used for studies of ignition. The activation energy and characteristics of ignition for the HEM samples were determined. Also, the ignition delay time and the surface temperature of the reaction layer during the heating and ignition for the HEM samples were determined. It was found that the complete replacement of micron-sized aluminum powder by amorphous boron in a HEM sample leads to a considerable decrease in the ignition delay time by a factor of 2.2-2.8 at the same heat flux density due to high chemical activity and the difference in the oxidation mechanisms of boron particles. The use of aluminum diboride in a HEM sample allows one to reduce the ignition delay time of a HEM sample by a factor of 1.7-2.2. The quasi-stationary ignition temperature is the same for the AlB2-based and AlB12-based HEM samples.

A thermoelectric device for ophthalmic heat flux density measurements: results of piloting in healthy individuals

2019 ◽  
Vol 80 (3) ◽  
pp. 45-51
Author(s):  
L. Anatychuk ◽  
N. Pasyechnikova ◽  
V. Naumenko ◽  
O. Zadorozhnyy ◽  
R. Kobylianskyi ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flux Density ◽  
Heat Flux Density ◽  
Thermoelectric Device ◽  
Healthy Individuals ◽  
Density Measurements

scholarly journals Expansion of the Range of Refrigeration of the Surface Heat Flow Unit Under Conductive Energy Produce

2018 ◽  
pp. 27-32
Author(s):  
S. Kovtun
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Flux Density ◽  
Heat Flux Density ◽  
Dynamic Range ◽  
Density Measurement ◽  
Lower Boundary ◽  
Surface Heat ◽  
Total Uncertainty ◽  
Unit Of Measurement

The article presents the results of investigations of factors that influence the accuracy of reproduction of the unit of measurement of the surface density of the heat flow by conductivity. Components of the uncertainty of the surface heat flux density measurement were analyzed using the Ishikawa cause-and-effect diagram, as shown in Fig. 1 The mathematical model of the method of reproduction of the unit of measurement was obtained, which takes into account the influence of the sources of uncertainty by making the corresponding corrections. The possibility of extending the lower boundary of the dynamic range by the correction of the factors having the greatest influence is substantiated. The rationale is based on the estimation of the uncertainty of the individual components, which, in the course of the correction of their impact, should not exceed the values (achieved to date). As an example, the calculation of the total uncertainty in the reproduction of the heat flux density of 20 W·m-2 is given. Table 1 contains all data important for the uncertainty analysis such as input quantities, their estimated values as well as the associated sensitivity coefficients and the variances determined.

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