Lorentz-force independence of resistance tails for high-temperature superconductors in magnetic fields nearTc

1989 ◽  
Vol 63 (17) ◽  
pp. 1877-1879 ◽  
Author(s):  
K. C. Woo ◽  
K. E. Gray ◽  
R. T. Kampwirth ◽  
J. H. Kang ◽  
S. J. Stein ◽  
...  
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?’.


MRS Bulletin ◽  
1992 ◽  
Vol 17 (8) ◽  
pp. 45-51 ◽  
Author(s):  
Eric E. Hellstrom

High-temperature superconductors are brittle oxide ceramics, yet they have been made into wire that has been wrapped into solenoids and used in demonstration magnets and motors. Fabricating wires from these ceramics is an extremely challenging materials science process that requires a precisely engineered microstructure with the correct chemical, mechanical, and electromagnetic properties if these wires are to transport large current densities (Jc) in high magnetic fields. Heine et al. first demonstrated that wires of these materials could carry high Jc in very high magnetic fields. At 4.2 K, the oxide superconducting wires can carry higher Jc at higher magnetic fields than conventional Nb-Ti or Nb3Sn wires (Figure 1), and as shown in the companion article in this issue by Kato et al. they can also have high Jc at 77 K.Of the three major families of high-temperature superconductors, YBa2Cu3O7-x, Bi-Sr-Ca-Cu-O (BSCCO), and Tl-Ba-Ca-Cu-O, the best wires to date have been made in the BSCCO system. At present, all YBa2Cu3O7-x wires are weak linked and have only small Jc in magnetic fields. In the Tl-based system, the superconducting properties are potentially very interesting, but the toxicity of Tl and the system's complex processing have limited conductor development. For the Bi-based system, the basic processing steps are becoming known, the grains are well connected, and the weak link problem can be controlled. This permits applications in the temperature range 4–77 K, depending on the field and current density requirements of the particular use.


2010 ◽  
Vol 23 (7) ◽  
pp. 075006 ◽  
Author(s):  
P Vanderbemden ◽  
P Laurent ◽  
J-F Fagnard ◽  
M Ausloos ◽  
N Hari Babu ◽  
...  

2005 ◽  
Vol 72 (5) ◽  
Author(s):  
Z. Wang ◽  
L. Shan ◽  
Y. Z. Zhang ◽  
J. Yan ◽  
F. Zhou ◽  
...  

2021 ◽  
Author(s):  
Jorge Hirsch ◽  
Frank Marsiglio

Abstract The Meissner effect, magnetic field expulsion, is a hallmark of superconductivity. Associated with it, superconductors exclude applied magnetic fields. Recently Minkov et al. presented experimental results reportedly showing ``definitive evidence of the Meissner effect'' in sulfur hydride and lanthanum hydride under high pressure [1]. Instead, we show here that the evidence presented in that paper does not support the case for superconductivity in these materials. Together with experimental evidence discussed in earlier papers, we argue that this clearly indicates that hydrides under pressure are not high temperature superconductors.


1990 ◽  
Vol 195 ◽  
Author(s):  
K. H. Lee ◽  
T.-K. Xia ◽  
D. Stroud

ABSTRACTWe review recent work on the dynamical behavior of coupled resistively-shunted Josephson junctions, with emphasis on our own calculations. We present a model which allows for the inclusion of finite temperature, disorder, d.c. and a. c. applied currents, and applied magnetic fields. We discuss applications to (a) calculations of critical currents and IV characteristics; (b) harmonic generation and microwave absorption by finite clusters of Josephson junctions; (c) critical energies for vortex depinning; and (d) quantized voltage plateaus in arrays subjected to combined d.c. and a. c. currents. Possible connections to the behavior of granular high-temperature superconductors are briefly discussed.


1990 ◽  
pp. 615-620
Author(s):  
Y. Iye ◽  
S. Nakamura ◽  
T. Tamegai ◽  
T. Terashima ◽  
Y. Bando

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