INDUCED CURRENT DISTRIBUTION IN A CONDUCTIVE TWO‐LAYER SPHERICAL BODY

Geophysics ◽  
1973 ◽  
Vol 38 (3) ◽  
pp. 530-544
Author(s):  
Chandra P. Gupta ◽  
Upendra Raval ◽  
Janardan G. Negi
Keyword(s):  
Current Distribution ◽  
Current Density ◽  
Spherical Body ◽  
Ore Deposits ◽  
Electromagnetic Response ◽  
Induced Current ◽  
Low Frequencies ◽  
Response Characteristics ◽  
The Core ◽  
Physical Insight

Under complex geologic situations the analysis of induced current distribution, rather than of the scattered field, may provide a useful physical insight into the electromagnetic response characteristics of a conducting ore body. Influence of a conducting cover and inhomogeneity in the conductivity on the currents induced in aspherical conductor excited by a uniform alternating magnetic field has, therefore, been investigated. The analysis shows (a) reduction of the current‐density amplitudes in the core by the cover, (b) occurrence of current‐density maxima inside the conducting system for some characteristic frequencies, (c) enhancement of the in‐phase component in some cases, and (d) reduction of current‐density in the shell with increase in the core conductivity and significant influence of the inhomogeneity in conductivity at low frequencies. Since there is a direct correspondence between the electromagnetic response of a target and the currents induced in it, these results are expected to aid in the interpretation of data over ore deposits having a halo‐zone of disseminated mineralization.

Scattering by a two-layer spherical dielectric object in a lossy medium illuminated by a loop carrying an arbitrary azimuthal mode

1989 ◽  
Vol 67 (6) ◽  
pp. 617-623
Author(s):  
A. Sebak ◽  
L. Shafai
Keyword(s):  
Current Distribution ◽  
Scattered Field ◽  
Near Field ◽  
Electromagnetic Response ◽  
Field Zone ◽  
Spherical Object ◽  
Azimuthal Mode ◽  
Low Frequencies ◽  
Circular Loop ◽  
Lossy Medium

The electromagnetic response of a circular loop antenna in the vicinity of a two-layer dielectric spherical object located in a lossy medium is investigated analytically. For a loop carrying an azimuthally dependent current distribution, a technique based on the dyadic Green's functions is employed to determine the fields in all regions. The formulation is general and can be applied to a wide variety of electromagnetic sources. Numerical results are presented in the near field zone and at low frequencies to determine the effect of the coating on the scattered field and its influence on the degree of detectability of a coated object.

scholarly journals The current distribution in an electrochemical cell. Part VII. Concluding remarks

2002 ◽  
Vol 67 (4) ◽  
pp. 273-278 ◽  
Author(s):  
Konstantin Popov ◽  
S.M. Pesic ◽  
Predrag Zivkovic
Keyword(s):  
Process Parameters ◽  
Current Distribution ◽  
Current Density ◽  
Electrochemical Cell ◽  
Side Wall ◽  
Cell Geometry ◽  
Electrode Edge ◽  
Side Walls ◽  
In Cells

Anew method for the determination of the ability of an electrolyte to distribute uniformly current density in an electrochemical cell is proposed. It is based on the comparison of the current in cells in which the electrode edges touch the cell side walls with the current in cells with different electrode edge ? cell side wall distances. The effects of cell geometry process parameters and current density are discussed and illustrated using the results presented in the previous papers from this series.

GaN MSM UV Sensor Using Multi-Layer Graphene Schottky Electrodes

2013 ◽  
Vol 481 ◽  
pp. 146-149 ◽  
Author(s):  
Chang Ju Lee ◽  
Hyeon Gu Cha ◽  
Seul Ki Hong ◽  
Seung Hyun Doh ◽  
Yi Sak Koo ◽  
...  
Keyword(s):  
Current Density ◽  
Applied Bias ◽  
Uv Sensor ◽  
Response Characteristics ◽  
Layer Graphene ◽  
Metal Type ◽  
Metal Semiconductor Metal ◽  
Uv Visible ◽  
Uv Response ◽  
First Time

We demonstrated a metal-semiconductor-metal type GaN UV sensor for the first time by using multi-layer graphene as a Schottky electrode. Multi-layer graphene shows good Schottky electrode characteristic and fabricated UV sensor shows good UV response characteristics. The maximum dark current density and photo-responsive current density were 6.42 × 10-9 A/cm2 and 5.57 × 10-5 A/cm2 at the 10 V bias, respectively. UV/visible rejection ratios were higher than 103 with each applied bias from 1 V to 15 V.

scholarly journals Velocity shear and current driven instability in a collisional F-region

2009 ◽  
Vol 27 (1) ◽  
pp. 381-394 ◽  
Author(s):  
P. J. G. Perron ◽  
J.-M. A. Noël ◽  
J.-P. St.-Maurice
Keyword(s):  
Dispersion Relation ◽  
Electron Temperature ◽  
Current Density ◽  
Threshold Current ◽  
Velocity Shear ◽  
Ion Temperature ◽  
Fluid Limit ◽  
Low Frequencies ◽  
F Region ◽  
Threshold Conditions

Abstract. We have studied how the presence of collisions affects the behavior of instabilities triggered by a combination of shears and parallel currents in the ionosphere under a variety of ion to electron temperature ratios. To this goal we have numerically solved a kinetic dispersion relation, using a relaxation model to describe the effects of ion and electron collisions. We have compared our solutions to expressions derived in a fluid limit which applied only to large electron to ion temperature ratios. We have limited our study to threshold conditions for the current density and the shears. We have studied how the threshold varies as a function of the wave-vector angle direction and as a function of frequency. As expected, we have found that for low frequencies and/or elevated ion to electron temperature ratios, the kinetic dispersion relation has to be used to evaluate the threshold conditions. We have also found that ion velocity shears can significantly lower the field-aligned threshold current needed to trigger the instability, especially for wave-vectors close to the perpendicular to the magnetic field. However the current density and shear requirements remain significantly higher than if collisions are neglected. Therefore, for ionospheric F-region applications, the effect of collisions should be included in the calculation of instabilities associated with horizontal shears in the vertical flow. Furthermore, in many situations of interest the kinetic solutions should be used instead of the fluid limit, in spite of the fact that the latter can be shown to produce qualitatively valid solutions.

scholarly journals Far-Field Plume Characterization of a 100-W Class Hall Thruster

Aerospace ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. 58
Author(s):  
Thibault Hallouin ◽  
Stéphane Mazouffre
Keyword(s):  
Energy Distribution ◽  
Current Density ◽  
Low Voltage ◽  
Ion Current ◽  
Hall Thruster ◽  
Far Field ◽  
Ion Energy ◽  
Ion Energy Distribution ◽  
The Core ◽  
Ion Current Density

The 100 W-class ISCT100-v2 Hall Thruster (HT) has been characterized in terms of far-field plume properties. By means of a Faraday Cup and a Retarding Potential Analyzer, both the ion current density and the ion energy distribution function have been measured over a 180 ∘ circular arc for different operating points. Measurements are compared to far-field plume characterizations performed with higher power Hall thrusters. The ion current density profiles remain unchanged whatever the HT input power, although an asymptotic limit is observed in the core of the plume at high discharge voltages and anode mass flow rates. In like manner, the ion energy distribution functions reveal that most of the beam energy is concentrated in the core of the plume [ − 40 ∘ ; 40 ∘ ] . Moreover, the fraction of low energy ion populations increases at large angles, owing to charge exchange and elastic collisions. Distinct plume regions are identified; they remain similar to the one described for high-power HTs. An efficiency analysis is also performed in terms of current utilization, mass utilization, and voltage utilization. The anode efficiency appears to be essentially affected by a low voltage utilization, the latter originating from the large surface-to-volume ratio inherent to low-power HTs. Experimental results also show that the background pressure clearly affects the plume structure and content.

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