Factors Influencing Critical Current Densities in High T sub c Superconductors

  • Fisanick G.

A key requirement for many practical application of the new class of high T sub c superconductors is the ability to sustain high current densities in the presence of magnetic fields. The new materials present two substantially different behaviors. For Ba sub 2 YCu sub 3 O sub 7 critical current behavior of polycrystalline material is dominated by intergranular transport. We will review a model for transport involving the effects of correlation of defects with grain boundary orientation, the presence of impurities at the grain boundaries, measurements of tunneling characteristics through the boundaries, and the effect of grain alignment on critical current. The case is substantially different in the 84K superconducting phase Bi sub (2.2) Sr sub 2 Ca sub (0.8) Cu sub 2 O sub (8+delta) where there is a very strong dependence of critical current densities at 30-84K on magnetic field for single crystals. There is a lack of threshold behavior in the I-V characteristics in finite applied fields larger than H sub (c1) (T) which is attributed to flux creep. This suggests that in the Bi material there is insufficient pinning of vortices in the intrinsic material to prevent them moving in the presence of an applied transport current, causing dissipation. The implications of these various factors on potential applications of these materials will be discussed.

Recent Publications

August 09, 2017

A Cloud Native Approach to 5G Network Slicing

  • Francini A.
  • Miller R.
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5G networks will have to support a set of very diverse and often extreme requirements. Network slicing offers an effective way to unlock the full potential of 5G networks and meet those requirements on a shared network infrastructure. This paper presents a cloud native approach to network slicing. The cloud ...

August 01, 2017

Modeling and simulation of RSOA with a dual-electrode configuration

  • De Valicourt G.
  • Liu Z.
  • Violas M.
  • Wang H.
  • Wu Q.

Based on the physical model of a bulk reflective semiconductor optical amplifier (RSOA) used as a modulator in radio over fiber (RoF) links, the distributions of carrier density, signal photon density, and amplified spontaneous emission photon density are demonstrated. One of limits in the use of RSOA is the lower ...

July 12, 2017

PrivApprox: Privacy-Preserving Stream Analytics

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  • Le D.
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How to preserve users' privacy while supporting high-utility analytics for low-latency stream processing? To answer this question: we describe the design, implementation and evaluation of PRIVAPPROX, a data analytics system for privacy-preserving stream processing. PRIVAPPROX provides three properties: (i) Privacy: zero-knowledge privacy (ezk) guarantees for users, a privacy bound tighter ...