Conductor Bulk Research Articles

Cauer Ladder Inspired Kron–Branin Modeling of Thermal 1-D Diffusion

This brief introduces an innovative unidimensional thermal propagation modeling. It consists in thermal diffusion on conductor bulk structure based on the Kron-Branin (KB) formalism. The proposed KB model is inspired from the transmission line approach by considering the bulk material thermal resistance and capacitance. The KB-based equivalent graph topology of the heated structure is elaborated. The thermal transfer function (TTF) is established from the graph analytical abstraction. The TTF enables to determine the transient and frequency-dependent temperature diffusion along the structure. The KB model effectiveness is illustrated with both frequency and time-domain analyses. Proof-of-concept constituted by copper-based bulk material is considered. The TTF from KB, finite-element-method and Cauer models are compared. With computation from dc to 100 Hz, it was shown that the frequency domain magnitude and phase are in good correction. In addition, the calculated and simulated transient heat flows along the considered structure are in good agreement by considering 120-ms duration pulse width temperature source.

Specific Features of the Nonlinear Diffusion of a Strong Pulsed Magnetic Field near the Conductor Edge

The nonlinear diffusion of a strong magnetic field to a conductor with the boundaries forming a right dihedral angle has been considered. In a transverse field with induction oriented perpendicular to the angle edge, the current density is maximum in the conductor bulk rather than near the edge (as for linear diffusion). In a longitudinal field with induction oriented parallel to the edge, the current density at the vertex of the angle at the strong-field diffusion is zero (as in a weak field); however, the maxima of the current density, temperature, and Lorentz force shift to the conductor bulk with an increase in the field strength.

Особенности нелинейной диффузии сильного импульсного магнитного поля вблизи края проводника

AbstractThe nonlinear diffusion of a strong magnetic field to a conductor with the boundaries forming a right dihedral angle has been considered. In a transverse field with induction oriented perpendicular to the angle edge, the current density is maximum in the conductor bulk rather than near the edge (as for linear diffusion). In a longitudinal field with induction oriented parallel to the edge, the current density at the vertex of the angle at the strong-field diffusion is zero (as in a weak field); however, the maxima of the current density, temperature, and Lorentz force shift to the conductor bulk with an increase in the field strength.

Multiphysics Analysis of Hemispherical Bulk Conductor Hertzian Contact Under Uniaxial Mechanical Load

A multiphysics model of smoothed contact surface hemispherical contact under dynamic vibration stress is treated in this paper. The contact structure is applied to hemispherical conductor bulk materials. The structure electrothermomechanical (ETM) behavior is investigated based on the Hertz contact theory coupled with electrokinetic approach. An electrical circuit integrating the contact material properties is proposed. The contact surface deformation ETM expression is formulated. The transient variations of the contact conductor material temperatures in function of the mechanical vibrations are analytically described. The ETM parameters range versus the mechanical load stress is analyzed by considering aluminum alloy material hemispherical bulk with a radius varying from 10 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m to 1 mm. The contact radius can be totally deformed when the load is increased up to 20 kN. In addition, an innovative multiphysics computational method is validated numerically to determine the transient variation of the contact surface radius model from SPICE simulation by considering 0.5 kHz/1 kHz frequency presenting 0.5-kN amplitude sine wave, and arbitrary waveform dynamic vibrations. It was conjectured from numerical application, the hemispherical bulk contact temperature, and also the mechanism multiphysics phenomena governing the structure behavior. As ongoing research, the equivalent system tensorial statement illustrating the multiphysics interaction between the conductor contacts will be developed.

Activation of metal oxidation over the zone of electrodiffusion

It is shown that an oxide layer saturated by chromium oxides is formed on the surface of chromium steel at a higher rate under electrocontact (104–105 A/cm2) vacuum dc annealing (10–2 Torr, 300°C) than under furnace heating. Such activation of oxidation is due to the formation of an electrodiffusion zone in the surface steel layer. At further stages, grain boundaries emerge to the metal surface that act as oxidant transportation channels from the surrounding medium into the conductor bulk, which results in accelerated oxide formation in the bulk of the surface metal layer. Apart from the uniform oxide layer, individual hematite nanoflakes and nanoleaves with the thickness of 50–40 nm and average diameter of 450 nm are formed on the positive electrode and grow vertically on the steel surface. The average surface density of nanoparticles is 108 1/cm2. Such activation of metal oxidation over the zone of electrodiffusion can provide pronounced properties for accelerated formation of protective surface layers, in addition to its intrinsic functional (sensor, catalytic, semiconductor, adsorption) properties.

Analysis of electric arc short-circuit consequences in ITER toroidal field coils

Abstract Based on the results of the ITER magnet system structure analysis the thermal analysis of a toroidal field coil in the case of short-circuit has been performed in view of the normal zone propagation (quench), as well as the conductor temperature and coil resistance rise. The electric arc behaviour within the magnet system is considered. The main results of calculations and theoretical study of the electrical arc under conditions typical for short-circuits in the magnet system coils are outlined. Theoretical physical models for an arc discharge burning within the insulation and conductor bulk are developed and described. Energy release in the arc is a matter of concern. Dangerous consequences of the arc discharge burning in the magnet system are estimated.

The capacitance of microstructures

The down sizing of devices has been so rapidly promoted that the device and the circuit feature size will break into the nanometer range less than 1000 Å at the beginning of the next century. It is of critical importance to investigate the characteristics of microstructure capacitances for analysis of future devices and circuits. We analyze the general features of microstructure capacitance based on the self-consistent field approximation, and clarify that it is decomposed into three components. One is the extension of the capacitance of classical perfect conductors discussed in electrostatics. The quantum-mechanical effect plays an important role in the other two components; one of them is proportional to the electronic density of states at the Fermi potential of the conductor in low temperatures. At room temperature this portion is proportional to the electronic charge in the conductor. The other is due to the delocalization of electronic charge off the surface into the bulk of conductor. These two components have only self-capacitance contributions. Various aspects of the microstructure capacitance, e.g., the order of magnitude, the diagrammatic expression, the charging energy, and the quantum dot charging are discussed.

Effect of Y 2BaCuO 5 particle size on the properties of YBa 2Cu3O 7-x superconductor

Abstract YBa 2Cu3O 7-x (123) bulk superconductor, which contained uniformly dispersed fine Y2BaCuO5 (211) grains, was fabricated with pre-synthesized Y 2BaCuO 5, BaO 2 and CuO powders by a partial melting process. The size reduction of pre-synthesized 211 powders by fine grinding and low temperature calcination had a positive effect on the homogeneous distribution of fine 211 grains in super- conductor bulk materials. The critical current density, J C, in a magnetic field increased approximately in proportion to the total surface area of 211 grains per unit weight in the 123 phase. When the magnetic field increased, the increase of J C with the increase of surface area of 211 grains became steep.