Externally phase-locked flux flow oscillator for submm integrated receivers: achievements and limitations

AbstractSoft-contact of molten steel can be achieved by applying a high-frequency electromagnetic field above the mold of continuous casting, which can effectively eliminate surface defects and achieve billets with no cracks and no oscillation marks. It also has some influence on the mold flux. In this study, the effect of a high-frequency electromagnetic field (20 kHz) on a mold flux flow field was simulated using a finite element software, and the slag film was extracted using a slag film simulator. The effect of the high-frequency magnetic field on the microstructure of the mold flux was analyzed using X-ray diffraction, Raman spectroscopy, and mineral phase testing. The results show that the high-frequency electromagnetic field disrupts the orderly movement and increases the movement rate of the liquid flux. The precipitate phase of the slag film did not change, but the silicate dimer Q1 decreased, the chain Q2 increased, and the network degree was increased. The slag film structure changed from the original two-layer form of crystalline layer–glass layer into a three-layer form of crystal layer–glass layer–crystal, and the crystallization ratio increased by 35% on average. The grain-size melilite granularity was reduced from the original 0.12 to 0.005 mm.

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High‐heat flux flow and heat transfer transitions in a supercritical loop: Numerical verification and correlation

International Journal of Energy Research ◽

10.1002/er.6696 ◽

2021 ◽

Author(s):

Dong Yang ◽

Lin Chen ◽

Jiaxiang Chen ◽

Yongchang Feng

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

High Heat ◽

High Heat Flux ◽

Numerical Verification ◽

Flux Flow ◽

Flow And Heat Transfer

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The activation energy U(T,B) in high temperature superconductor

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020200223 ◽

2020 ◽

Vol 92 (2) ◽

pp. 20601

Author(s):

Abdelaziz Labrag ◽

Mustapha Bghour ◽

Ahmed Abou El Hassan ◽

Habiba El Hamidi ◽

Ahmed Taoufik ◽

...

Keyword(s):

Magnetic Field ◽

Activation Energy ◽

Phase Diagram ◽

High Temperature ◽

Apparent Activation Energy ◽

High Temperature Superconductor ◽

Flux Flow ◽

Resistivity Measurements ◽

Vortex Phase ◽

The Magnetic Field

It is reported in this paper on the thermally assisted flux flow in epitaxial YBa2Cu3O7-δ deposited by Laser ablation method on the SrTiO3 substrate. The resistivity measurements ρ (T, B) of the sample under various values of the magnetic field up to 14T in directions B∥ab-plane and B∥c-axis with a dc weak transport current density were investigated in order to determine the activation energy and then understand the vortex dynamic phenomena and therefore deduce the vortex phase diagram of this material. The apparent activation energy U0 (B) calculated using an Arrhenius relation. The measured results of the resistivity were then adjusted to the modified thermally assisted flux flow model in order to account for the temperature-field dependence of the activation energy U (T, B). The obtained values from the thermally assisted activation energy, exhibit a behavior similar to the one showed with the Arrhenius model, albeit larger than the apparent activation energy with ∼1.5 order on magnitude for both cases of the magnetic field directions. The vortex glass model was also used to obtain the vortex-glass transition temperature from the linear fitting of [d ln ρ/dT ] −1 plots. In the course of this work thanks to the resistivity measurements the upper critical magnetic field Hc2 (T), the irreversibility line Hirr (T) and the crossover field HCrossOver (T) were located. These three parameters allowed us to establish a phase diagram of the studied material where limits of each vortex phase are sketched in order to optimize its applicability as a practical high temperature superconductor used for diverse purposes.

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ANISOTROPIC VORTEX DYNAMICS AND PHASE DIAGRAM OF YBa2Cu3O7 SINGLE CRYSTALS WITH CANTED COLUMNAR DEFECTS

International Journal of Modern Physics B ◽

10.1142/s0217979296001215 ◽

1996 ◽

Vol 10 (22) ◽

pp. 2723-2743 ◽

Cited By ~ 10

Author(s):

D. S. REED ◽

N.-C. YEH ◽

W. JIANG ◽

U. KRIPLANI ◽

M. KONCZYKOWSKI ◽

...

Keyword(s):

Phase Diagram ◽

Magnetic Fields ◽

Vortex Dynamics ◽

Flow Model ◽

Flux Flow ◽

Thermally Activated ◽

Liquid Transition ◽

Columnar Defects ◽

Thermally Activated Flux Flow ◽

Activated Flux

The anisotropic vortex dynamics and phase diagram are determined for a YBa 2 Cu 3 O 7 single crystal with columnar defects oriented at ±7.5° relative to the crystalline c-axis. A second-order splayed-glass to vortex-liquid transition is manifested for magnetic fields nearly parallel to the columns via the critical scaling of vortex AC and DC transport properties. In contrast, for magnetic fields aligned close to the ab-plane, an XY-like vortex-glass transition prevails. For magnetic fields at intermediate angles, there is no evidence of any vortex phase transition, and the vortex dynamics is described in terms of the thermally activated flux flow model.

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