Effects of ac field on depinning current density in type-2 superconductors

1971 ◽  
Vol 36 (4) ◽  
pp. 341-342 ◽  
Author(s):  
K. Yamafuji ◽  
N. Sakamoto ◽  
T. Kawashima
Keyword(s):  
1998 ◽  
Vol 12 (27) ◽  
pp. 1117-1124 ◽  
Author(s):  
A. V. Pop

The effect of Fe 3+ ions on the inter- and intragranular Tp and Tg temperatures of the imaginary peaks of the AC susceptibility has been studied for a (Bi, Pb):2223 superconductor. The linear dependencies of Tp and Tg as a function of AC field amplitude agree with Muller critical state model. The Fe 3+ ions induced a fast decrease of inter and intragranular pinning force densities. The intergrain critical current density J cj calculated from χ″(T) curve is lower in x=0.02 Fe doped sample than in x=0.00 sample. J cj (T) dependence near Tc agrees with the assumption of SNS intergrain junctions.


1999 ◽  
Vol 85 (8) ◽  
pp. 4469-4470 ◽  
Author(s):  
Scott W. Stokes ◽  
William L. Wilson ◽  
Bruce M. Lairson

1986 ◽  
Vol 29 (10) ◽  
pp. 930-933
Author(s):  
Yu. K. Alekseev ◽  
A. I. Kostienko

1997 ◽  
Vol 11 (29) ◽  
pp. 3461-3467 ◽  
Author(s):  
A. V. Pop ◽  
R. Deltour ◽  
A. Harabor ◽  
D. Ciurchea ◽  
Gh. Ilonca

The temperature and amplitude of AC field dependencies of both inter-and intragranular T p and T g temperatures of the imaginary peaks of χ′′ has been studied for a sintered single phase (Bi,Pb):2223 superconductor. The AC field dependencies for T p and T g and the relation between inter- and intragrain force densities were discussed by using Müller critical-state model. From the χ′′(T) curve, the values of intergrain magnetic critical current density J cJ was obtained via the application of Bean's critical state model. J cJ (T) dependence near T c agree with the assumption of SNS intergrain junctions.


2003 ◽  
Vol 17 (21) ◽  
pp. 3807-3811
Author(s):  
V. Pop

The (Bi,Pb)(Sr,Ba) :2223 samples were prepared using different sintering temperatures. The electrical properties were investigated by electrical resistance and V–I characteristics measurements. The increase of sintering temperature induces the decrease of transition width and the increase of intergranular critical current density Jcj and phase purity. The critical current density from electrical measurement agrees with the results obtained from complex magnetic susceptibility measurements function of temperature and AC field amplitude.


1999 ◽  
Vol 13 (14n16) ◽  
pp. 1775-1782 ◽  
Author(s):  
C. Boissy ◽  
C.W. Wu ◽  
Y. Fahmy ◽  
H. Conrad

Recently a model describing the interaction between the particles of an electrorheological suspension and the resulting properties (yield stress, current density) has been proposed by Wu and Conrad. This model takes into account both the conductivity and the permittivity of each constituent of the suspension and predicts the behavior under DC and AC fields. The goal of the present work is to compare the predictions of this model with data available in the literature and with additional experiments using DC and AC fields at frequencies up to 2000 Hz. The ER fluids used in our experiments are suspensions of different ceramics particles ( Al 2 O 3, ZrO 2, TiO 2, CaTiO 3, BaTiO 3) in silicone oil. These particles cover a wide range of permittivity and conductivity, which allows us to study the ER effect with varying values of the conductivity and/or permittivity mismatch between the particles and the liquid. The model is in reasonable accord with experiment.


1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.


Author(s):  
P. Lu ◽  
W. Huang ◽  
C.S. Chern ◽  
Y.Q. Li ◽  
J. Zhao ◽  
...  

The YBa2Cu3O7-x thin films formed by metalorganic chemical vapor deposition(MOCVD) have been reported to have excellent superconducting properties including a sharp zero resistance transition temperature (Tc) of 89 K and a high critical current density of 2.3x106 A/cm2 or higher. The origin of the high critical current in the thin film compared to bulk materials is attributed to its structural properties such as orientation, grain boundaries and defects on the scale of the coherent length. In this report, we present microstructural aspects of the thin films deposited on the (100) LaAlO3 substrate, which process the highest critical current density.Details of the thin film growth process have been reported elsewhere. The thin films were examined in both planar and cross-section view by electron microscopy. TEM sample preparation was carried out using conventional grinding, dimpling and ion milling techniques. Special care was taken to avoid exposure of the thin films to water during the preparation processes.


Author(s):  
J. R. Michael ◽  
A. D. Romig ◽  
D. R. Frear

Al with additions of Cu is commonly used as the conductor metallizations for integrated circuits, the Cu being added since it improves resistance to electromigration failure. As linewidths decrease to submicrometer dimensions, the current density carried by the interconnect increases dramatically and the probability of electromigration failure increases. To increase the robustness of the interconnect lines to this failure mode, an understanding of the mechanism by which Cu improves resistance to electromigration is needed. A number of theories have been proposed to account for role of Cu on electromigration behavior and many of the theories are dependent of the elemental Cu distribution in the interconnect line. However, there is an incomplete understanding of the distribution of Cu within the Al interconnect as a function of thermal history. In order to understand the role of Cu in reducing electromigration failures better, it is important to characterize the Cu distribution within the microstructure of the Al-Cu metallization.


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