Square Of Magnetic Flux Density Research Articles

Research on Electric Conductivity of Thermo-plastic Composites Based on Eddy Current Loss

Thermoplastic composites has attracted extensive attention in industrial process with excellent properties. As one of the most important parameters, electric conductivity is difficult to detect due to its inhomogeneity and anisotropy. In this paper, a novel method for measuring volume electric conductivity of composites based on eddy current loss has been introduced by using both experimental and numerical approaches. Initially, the eddy current loss and equivalent volume conductivity under different magnetic flux density are presented by analyzing voltage and current acquired in a designed air-gapless reactor under 500 Hz sinusoidal excitation with variety amplitudes. Then, to verify the measurement method and determine the influence of different materials on the eddy current loss, a 3-D electromagnetic model of the experimental devices is built and three cases with different materials are calculated. The parameters including eddy current loss and magnetic flux density are presented. The mechanism underlying the influence of different conductivity on the measuring model is analyzed according to the confidents and eddy current loss. Results show that the ratio of eddy current loss to the square of magnetic flux density is linear. The formula of equivalent volume conductivity needs to be revised by multiplying certain coefficients for high conductivity due to the eddy current effect on the detection coil. It is reasonable that magnetic flux density rang is set in 0.2~0.8T during measurement.

Selective electromagnetic induction heating of metal particles in molten salt for tritium extraction: A systematic numerical investigation

Molten-salt blankets that possess tritium-absorbing metal particles are promising emerging technical components in nuclear fusion reactors. In this study, we develop a numerical model and carry out a systematic analysis of the electromagnetic induction heating of metal particles (Ti, Pd, Mg, Zr, and V) in the molten salt for the extraction of tritium. We show that the maximum absorption power in the metal particles can be normalized in a form independent of the material combination of nonmagnetic metals and salts, and the peak power density per square of magnetic flux density per field frequency is 5.3 × 106 W m–3 T–2 s. Nevertheless, the steady-state temperature difference between the metal particles and the molten salt, a figure of merit of the selective electromagnetic heating scheme, is found to monotonically increase with the metal particle size, in contrast to the behavior of the absorbed power density, thus encouraging the use of larger metal particles. The attainable temperature difference between the Ti particles and the FLiBe blanket is estimated to be 110 °C for a particle diameter of 1 mm in a 2.45 GHz and 1 mT magnetic field, and it increases proportionally with the diameter, square root of frequency, and square of magnetic flux density around this condition.

High-performance nonequilibrium-plasma magnetohydrodynamic electrical power generator using slightly divergent channel configuration: I. Calculation

We describe quasi-three-dimensional numerical simulations of a high-performance nonequilibrium-plasma magnetohydrodynamic (MHD) electrical power generator using a slightly divergent configuration. The slightly divergent generator provides greater isentropic efficiency (IE) than a highly divergent generator when an identical enthalpy extraction ratio (EER) is obtained. The inherent feature of a small divergent geometry is clarified; MHD energy conversion is accompanied by less entropy production as well as less gas expansion. The orientation of the performance improvement on an IE–EER map is consistent with the theoretically predicted orientation, which is formulated using an algebraic method based on classical thermodynamic results for supersonic compressible fluid dynamics. The power-generating performance indicators, IE and EER, are clearly determined by modified magnetic flux density, that is, the square of magnetic flux density divided by total inflow pressure. A virtual operating condition for a practical closed-cycle MHD system is proposed considering the relationships between the applied magnetic flux density, the total inflow pressure and the total pressure gradient throughout the generator. This paper is the first part of a duology.

Effects of Magnetic Field on the Electroless Nickel/Cobalt Deposition

Effects of magnetic field on the electroless nickel/cobalt deposition using electroless nickel/γ-Al2O3 as the support and a hypophosphite ion as the reducing agent in the alkaline solution were studied. The active sites for electroless nickel/cobalt deposition were divided into three types in which the first type of active sites were occupied by both nickel ion and cobalt ion and the second and third types of active sites were occupied by the hypophosphite ion. Three exponential equations for the rate constants of nickel, cobalt, and hypophosphite ions were obtained, respectively. The plots of logarithms of rate constants were linear with the square of magnetic flux density. Based on the results of hydrogen gas evolution rate, the recombinations of Ni+a•/Ha• and Co+a•/Ha• radical pairs were affected by the magnetic field; however, the Ha• radicals did not separate from these radical pairs.

Mhd pressure drop along a nak flow around a stepwise change of tube diameter under a transverse magnetic field

The MHD pressure drop along a liquid metal NaK flow was measured around the junction of 3/4 in. and 1 1/2 in. o.d. circular 304-SS tubes under a transverse magnetic field in order to investigate the MHD effect of a sudden change of flow cross-section, since such a joint would be used in the design of MCF power reactors. The size and thickness of the tubes was chosen so that the wall-to-fluid electric conductance ratio C was almost the same between the large and small tubes. The experimental ranges: B = 0–1.5 T (Ha = 0–1400 for the smaller tube and Ha = 0–2800 for the larger tube), and Us = 0.2–2.4 m/s (Re = 3600–43 200). For the case of expanding flow, the pressure drops singularly in a distant location downstream from the junction and the singular location comes closer to the junction as the magnetic field is increased. The pressure drop between the two points just upstream and downstream of the junction is proportional to the mean flow velocity U times the square of magnetic flux density B. With increasing UB2, this pressure drop is reduced nearly to the sum of the MHD pressure drops predicted in the respective straight part of the small and large tubes. For the case of contracting flow, the pressure has a similar trend but scatters to a larger extent across the junction.