Influence Of Current Distribution Research Articles

The electro-thermo-optical characteristics and limiting energy capabilities of high-power deep ultraviolet light emitting diodes (λ~ 270 nm)

The current and temperature dependences of the electrical, power and spectral characteristics of high-power deep-UV LEDs (λ~ 270 nm) have been studied. The main parameters of LED (internal quantum efficiency and light extraction efficiency) which determine output power capacity of the UV LED have been calculated using the ABC-model. The influence of current distribution, electrical losses and thermal resistance as factors limiting the energy capabilities was estimated. Keywords: AlGaN, UV LED, quantum efficiency, light extraction efficiency, temperature dependence, ABC-model.

Электротермооптические характеристики и предельные энергетические возможности мощных AlGaN-светодиодов глубокого ультрафиолетового диапазона (λ~ 270 nm)

The current and temperature dependences of the electrical, power and spectral characteristics of high-power deep UV LEDs (λ≈ 270 nm) have been studied. The main parameters of LED (internal quantum efficiency and light extraction efficiency) which determine output power capacity of the UV LED are calculated using the ABC-model. The influence of current distribution, electrical losses and thermal resistance as factors limiting the energy possibilities were estimated.

Drift velocity of charged particles in magnetic fields and its relation to the direction of the source current

Integrable motion of charged particles in magnetic fields produced by stationary current distributions is investigated. We treat motion in the magnetic field from an infinite flat current sheet, a Harris current sheath, an infinite rectilinear current, and a dipole in its equatorial plane. We find that positively charged particles as a rule will drift in the same direction as the current that is the source of the magnetic field in question. The conclusion is that charged particles moving under the influence of current distributions tend to enhance the current and that this indicates current self-amplification.

Influence of geometry-induced current and potential distributions on the characterization of constant-phase element behavior

Electrode geometry is abruptly truncated at the metal insulating boundary. A theoretical analysis has shown that disk-electrode geometry induces current and potential distributions that influence the impedance response in the high frequency domain. In this paper we investigate the extent of this influence on an experimental system displaying constant-phase element (CPE) behavior. We shall focus on the influence of these current distributions on the characterization of underlying CPE behavior from the analysis of the imaginary part of the impedance, although we shall also address results obtained from the complex non-linear fitting of impedance data to an equivalent circuit. The crossover from CPE behavior to this geometry-dominated regime establishes an upper cutoff in the experimental frequency range employed to characterize CPE response. We discuss the experimental conditions for which this crossover may prevent the analysis of experimental results to reveal the real underlying CPE behavior. The results and conclusions here obtained agree with previous theoretical modeling. Taking into account the limitations presented here can help to a better characterization and a deeper understanding of the frequency dispersion in the response of solid electrodes.

The effect of non-uniform current distribution on transport current loss in stacked high-Tcsuperconductor tapes

The influence of current distribution on the transport current loss in vertically stacked high-<TEX>$T_c$</TEX> superconductor (HTS) tapes was evaluated. AC loss was analyzed as a function of current distribution by introducing a current distribution parameter through a numerical method (finite element analysis). AC loss under non-uniform current distribution is always higher than that for a uniformly distributed transport current in a conductor. Although the effect of non-uniformity is relatively insignificant in low transport current, AC loss increases substantially in high transport current regions as non-uniformity is enlarged. The results verify that non-uniform current distribution causes extra loss by examining the cross-sectional view of current densities in stacked conductor.

The Influence of Current Distribution on Battery Design and Performance

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Effect of Current Distribution on AC Losses in the Multi-Stacked Superconducting Tapes

According to the recent design of an HTS (high temperature superconducting) power application whose capacity is hundreds MVA, the rated current is over thousand amps. Considering the performance of the recent HTS tapes, it is inevitable to use several HTS tapes in parallel for high capacity current. In this paper, we have investigated the influence of current distribution on the AC loss in the multi-stacked superconducting wire. The dependence of AC loss and critical current on the current distribution in multi-stacked wires was discussed. We fabricated multi-stacked wires and measured the current distribution at 77 K. The current distribution was indirectly found from the self-field distribution. The magnetic field was measured by an array of hall sensors located around the HTS superconducting wires. In the case of non-uniform distribution of current, the performance of multi- stacked HTS wires is worse than that of uniform current distribution.

Influence of Non-Uniform Current Distribution on AC Transport Current Loss in Bi-2223/Ag Tapes

This paper presents the influence of current distribution on AC transport current loss in multi-strand high-temperature superconductor (HTS) tapes. The current-distribution-dependent-AC loss is analyzed by introducing a current distribution parameter. We calculated AC loss of multi-strand HTS tapes numerically and performed AC loss measurements as well. Though the effect of current distribution on AC transport current loss is relatively insignificant for a low applied transport current, the effect of nonuniform current distribution seriously increases AC loss for a high applied transport current. The AC loss measurement method used in this paper is also confirmed by comparison with numerical results: the experimental and computational results showed good agreement for various current distribution parameters

Influence of current distribution on conductor performance in coaxial multi-layer HTS conductor

We have developed a simulation method based on magnetic flux conservation between two filaments of adjacent layers to estimate current distribution in coaxial multi-layer HTS conductor. Using this method, we have demonstrated homogeneous current distribution and verified that current distribution was controllable directly by the conductor parameters of layer radius, twisting pitch and twisting direction. Although it has been considered that homogeneous current distribution is effective for reducing AC loss, the most suitable conductor parameters and operating condition have not been investigated sufficiently yet. Therefore, we improved our developing method to estimate current distribution more rigorously considering the nonlinear voltage-current characteristic of HTS tape. To verify the validity of the simulation method, we measured current distribution using coaxial two-layer conductors. Agreement of current distribution between the experiment and the analysis was good.

Influence of current distribution on quench process in noninsulated AC multi-strand superconducting cables

In AC multi-strand superconducting cables, AC quench current is much less than that of DC. This AC quench current degradation is caused by AC loss, mechanical damage by cabling, nonuniform current distribution among strands due to self and mutual inductances between strands, and different electrical resistivity at the joint between superconducting strands and current lead. In this paper, the current distribution and the thermal behavior of noninsulated 7- and (6+1)-strand cables applying AC transport current are analyzed and the influence of contact electrical resistivity on the current redistribution and the thermal diffusion in the quench process are investigated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Quench characteristics and current distribution of multi-strand AC superconducting cables

When AC transport current is supplied to an imperfectly transposed AC superconducting cables, the current distribution among strands becomes nonuniform because of the inductance imbalance. The influence of the nonuniform current distribution on the AC quench characteristics of seven-strand cables was experimentally investigated. It was observed that the center strand carries the inverse current as compared to the total transport current. The influence of the current distribution on the quench current is discussed. The AC quench currents of the following three cases are compared: a seven-strand cable with small series impedance, a seven-strand cable with large series impedance, and a six-strand cable. The quench current of the second case was the largest, and that of the first case was the smallest. It can be qualitatively explained by the current distribution among strands, but the difference between their quench currents was smaller than expected. In a seven-strand cable with small series impedance, the magnitude of the inverse current in the center strand was smaller than the theoretical value. Its peak was eliminated when the total transport current became large.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Influence of current distribution on electrode potentials in bipolar water electrolysis cells of the ?sandwich? type

The potential and current density distributions in a bipolar electrolytic cell for water electrolysis were computed and the solution given as a matrix product. This makes a rapid and simple evaluation of the load-bearing capacity of such a cell possible, taking into consideration the resistance of the bipolar plate and the supply lines, the reciprocal position and gaps of the current bars and the relative resistance characteristics of the two electrodes. At the same time, the electrochemical process was included by means of Tafel parameters. The variation in these data has been given in a dimensionless form and is discussed in detail.