Optimal Vortex Pinning in YBa2Cu3O7-x Superconducting Films Up to Very High Magnetic Fields

Author(s):  
Ferran Vallès ◽  
Anna Palau ◽  
Dmytro Abraimov ◽  
Jan Jaroszynski ◽  
Anca-Monia Constantinescu ◽  
...  

Abstract The magnetic flux pinning capabilities of YBa2Cu3O7−x (YBCO) coated conductors (CCs) vary strongly between different regions of the magnetic field-temperature (H-T) diagram and with the orientation of the magnetic field (θ). Here, we determine the optimal pinning landscape for a given H-T region by investigating the critical current density Jc(H,θ,T) in the 5-77 K temperature range, from self-field to very high magnetic fields (35 T). Our systematic analysis reveals the best directions to target to artificially engineer CCs in any region of interest. In solution-derived nanocomposites, we identify the relevance of coexisting high amounts of short stacking faults, Cu-O vacancy clusters and segmentation of twin boundaries, in combination with nanoparticles, for enhanced pinning performance at very high magnetic fields and low temperatures. Moreover, we demonstrate that twin boundaries preserve a high pinning energy in thick YBCO films, which is beneficial for the pinning performance at high magnetic fields and high temperatures.

2002 ◽  
Vol 12 (9) ◽  
pp. 389-389
Author(s):  
W. G. Clark ◽  
F. Zamborsky ◽  
B. Alavi ◽  
P. Vonlanthen ◽  
W. Moulton ◽  
...  

We report proton NMR measurements of the effect of very high magnetic fields up to 44.7 T (1.9 GHz) on the spin density wave (SDW) transition of the organic conductor TMTSF2PF6. Up to 1.8 GHz, no effect of critical slowing close to the transition is seen on the proton relaxation rate (1/T1), which is determined by the SDW fluctuations associated with the phase transition at the NMR frequency. Thus, the correlation time for such fluctuations is less than $1O^{-10}$s. A possible explanation for the absence of longer correlation times is that the transition is weakly first order, so that the full critical divergence is never achieved. The measurements also show a dependence of the transition temperature on the orientation of the magnetic field and a quadratic dependence on its magnitude that agrees with earlier transport measurements at lower fields. The UCLA part of this work was supported by NSF Grant DMR-0072524.


2009 ◽  
Vol 23 (1) ◽  
pp. 014003 ◽  
Author(s):  
A Xu ◽  
J J Jaroszynski ◽  
F Kametani ◽  
Z Chen ◽  
D C Larbalestier ◽  
...  

Author(s):  
Dennis Whyte

The advantages of high magnetic fields in tokamaks are reviewed, and why they are important in leading to more compact tokamaks. A brief explanation is given of what limits the magnetic field in a tokamak, and why high temperature superconductors (HTSs) are a game changer, not just because of their higher magnetic fields but also for reasons of higher current density and higher operating temperatures. An accelerated pathway to fusion energy is described, defined by the SPARC and ARC tokamak designs. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.


2019 ◽  
Vol 52 (5) ◽  
pp. 945-950 ◽  
Author(s):  
Shulin Dong ◽  
Tie Liu ◽  
Meng Dong ◽  
Shuang Wang ◽  
Wen Wang ◽  
...  

This paper investigates how applying high magnetic fields influences the crystallographic orientations of the primary and eutectic phases, and their relationship, in a binary eutectic alloy. At 0 T, the primary MnSb phase in hypoeutectic Mn–Sb showed a random orientation, but at 3, 6, 9 and 11.5 T, its c axis was perpendicular to the magnetic field direction. In all cases, the eutectic MnSb phases showed the same orientations as their neighboring primary MnSb phase, on which they nucleated and grew. With high magnetic fields, the c axes of the eutectic and primary MnSb phases were oriented perpendicular to the magnetic field direction. The results show that applying a high magnetic field during solidification is a way of controlling the crystallographic orientation of both the primary and the eutectic phases in eutectic alloys.


2004 ◽  
Vol 18 (27n29) ◽  
pp. 3813-3816 ◽  
Author(s):  
A. B. HENRIQUES ◽  
L. K. HANAMOTO ◽  
E. TER HAAR ◽  
E. ABRAMOF ◽  
A. Y. UETA ◽  
...  

The near band-edge polarized optical optical absortion spectra of EuTe at low temperatures and high magnetic fields were investigated. The samples were grown by MBE on BaF 2 substrates, and the thickness varied in the 0.18-2.0 μm range. At high magnetic fields, the well-known 4f7→4f65d(t2g) optical transition splits into two well resolved lines at σ+ and two lines for σ-. These lines can be described by localized transitions tunable by the d-f exchange interaction, with a quadratic dependence on the intensity of the external magnetic field. Comparative measurements of the magnetization and the optical absorption as a function temperature provides a further test of the model of a localized excitation extending over a few lattice sites.


1991 ◽  
Vol 05 (20) ◽  
pp. 3255-3265 ◽  
Author(s):  
V.M. SVISTUNOV ◽  
A.I. D’YACHENKO ◽  
V. YU. TARENKOV

The efficiency of high pressure technique for the evidence of the Josephson nature of the intergranular contacts in metal ceramics has been demonstrated. With this technique it has been found that the abnormal hysteresis in fields of the order of tens kOe was not connected with the short-circuited contacts between the granules. The reason for the hysteresis lies in the ambiguity of the magnetization of the granules versus the change in the magnetic field direction. The critical current stability of the Josephson conteacts to high magnetic fields is due to both the inhomogeneity of the contacts and the existence of Abrikosov vortices within the superconducting electrode links.


2002 ◽  
Vol 89 (23) ◽  
Author(s):  
M. Muralidhar ◽  
N. Sakai ◽  
N. Chikumoto ◽  
M. Jirsa ◽  
T. Machi ◽  
...  

2006 ◽  
Vol 113 ◽  
pp. 459-464 ◽  
Author(s):  
J. Novickij ◽  
V. Stankevič ◽  
S. Balevičius ◽  
N. Žurauskienė ◽  
P. Cimmperman ◽  
...  

Magnetic field sensors based on polycrystalline La0.83Sr0.17MnO3 films were used to measure the magnetic field distribution and disturbances during the operation of an electromagnetic launcher. Hollow cylinders made from dural aluminum and iron were used as propelled objects inside the solenoidal coil. The obtained results revealed the ability of manganite sensors to rapidly measure changing high magnetic fields of arbitrary waveforms.


1984 ◽  
Vol 31 (3) ◽  
pp. 381-393 ◽  
Author(s):  
M. A. Liberman ◽  
A. L. Velikovich

Ignition of a self-sustained fusion reaction in a strong magnetic field is studied. The critical ignition dimensions and the threshold ignition energy are calculated as functions of the fuel density and the magnitude of the transverse magnetic field. A new method for producing ultra-high magnetic fields is proposed which provides at once heating of the fuel by induction currents and localization of the micro-explosion by the magnetic field. Simple analytic estimates show that a certain combination of inertial, magnetic and wall methods of plasma confinement may decrease the ignition energy below 100 kJ.


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