The effect of the time dependent angular distribution of the intergrain magnetic field on the transport critical current in Ag-(Bi,Pb)2Sr2Ca2Cu3Ox tapes

Abstract

Changes in the energy dissipation of the tape form Ag-(Bi,Pb)2Sr2Ca2Cu3Ox conductor have been interpreted in terms of magnetic flux movement from, or into, the intergrain regions of the highly textured plate like grain structure. The time dependent increase or decrease of the transport critical current (Ic), originates from time dependent angular superposition of the current induced self field (HSF), and external magnetic field [field cooling (HFC), and zero-field cooling (HZFC)] at the intergrain regions. The existence of time dependent changes of Ic can be explained in terms of the time dependent flux redistribution in grains and grain boundaries caused by thermal relaxation processes.

Barrier Properties for Oxygen Diffusion in a TaSiN Layer

“…Being consistent with this statement, our results show that a best linear dependence requires the dominance of strong-link critical current. In the case of weak-link dominance as in figure 4(a), there is a strong time and hysteresis effect on I c [23][24][25], which causes large data scattering and even results in branches in the I c versus B f s (θ ) plot.…”

Transport ac losses in Bi-2223 multifilamentary tapes - conductor materials aspect

“…Critical current measurements conducted on the 6 + 1 filamentary tape (produced by Metals Manufacture) in close proximity to NiFe tape of the same width as a superconducting tape proved that critical current was reduced 8% from its original value and also the n value was reduced. Additionally it was observed that in both cases the I -V characteristic during current reduction was shifted towards higher values of the critical current indicating time dependent changes of the flux distribution in the intergranular region as explained by Glowacki et al (1996). The presence of the magnetic material appears to have a detrimental influence on the ac losses, figure 7.…”

Dynamical hysteresisV–Icurves of superconductors

“…On the other hand, when a ZFC V -I curve is measured at the initial state with j col , the clockwise loop will be detected. One can find the relevant experimental evidences from [7,11], just as seen in single crystals 2H-NbSe 2 [6]. Thus, the simulation is useful for understanding the dynamical hysteresis originating from different mechanisms in a variety of samples, including those reported in [1,2].…”

“…Most major electric or/and magnetic phenomena in superconductors are strongly coupled to dynamical and non-equilibrium processes, in particular, those responsible for the pronounced history effect (HE) of vortex matter frequently observed in thermal, magnetic and current cycles. One type of HE in electric transport measurement, the hysteresis loop of V -I curves, has drawn much attention recently [1][2][3][4][5][6][7][8][9][10][11][12][13]. Several types of hysteresis loop have been observed and different explanations have been proposed.…”

“…In addition, the direction of the V -I loop relating to the specific conditions in experiments (such as zero-field cooling (ZFC) or 3 Author to whom any correspondence should be addressed. field cooling (FC), or the field direction) has been attributed to the inhomogeneity of the flux pinning strength for polycrystalline superconductors [7][8][9][10][11]. However, there are still some problems beyond our grasp.…”