[en] When a local normal zone appears in a cable-in-conduit superconductor, a slug of hot helium is produced. The pressure rises and the hot helium expands. Thus the normal zone propagation in such a conductor can be governed by the hot helium expansion, rather than the heat conduction along the conductor. The expansion of the hot helium compresses the cold helium outside of the normal zone. This raises the temperature of the cold helium. When the temperature rise reaches the current sharing limit, the superconductor in contact goes normal. Thus a rapid increase in normal zone propagation occurs. This phenomenon is termed Thermal Hydraulic Quenchback (THQ). An experiment was performed to investigate this process. The existence of THQ was verified. Thresholds of THQ were also observed by varying the conductor current, the magnetic field, the temperature, and the initial normal zone length. When THQ occurred, normal zone propagation approaching the velocity of sound was observed. A better picture of THQ is obtained by a careful comparison of the data with analytical studies

No abstract available

[en] A technique has been developed for the braiding of large numbers of superconducting wires into fully transposed, rectangular cross section conductors of low aspect ratio. The technique is derived from textile industry lattice braiding used to manufacture square cross section braids which are not, however, fully transposed. The void structure of the lattice braid cross section is superior, for axial forced flow cooling, to folded flat braids and to triplex cables. The lattice braided conductor also has an effective transposition length which is much shorter than its actual transposition length; because of the geometry of the wire path through the cross section, axial magnetic field coupling is cancelled out over lengths which can be only fractions of the actual transposition length. A prototype braid sample has been fabricated from insulated superconducting wire which exhibits the advantages expected. Application of this type of conductor to large force-cooled and/or pulsed coils is discussed. 3 refs

[en] If the level of a liquid cryogen inadvertently falls below the top of a magnet winding, it may expose a segment of the conductor. Depending on the length of the uncooled segment and on how the matrix resistivity varies with temperature, zero, one, or two steady normal states may be possible. The stability of the various steady states, the conditions under which they appear, their energies of formation, and the voltages they produce are studied in this paper

[en] The rising demand for electricity conflicts with opposition to overhead transmission lines. Underground lines that are refrigerated to be superconducting may provide a solution

[en] One of the design features which yet offers interesting margins for performance optimization of cable-in-conduit conductors (CICCs), is their geometry. For relatively small size Nb₃Sn CICCs, operating at high electromagnetic pressure, such as those for the EDIPO project, it has been experimentally shown that a design based on a rectangular layout with higher aspect ratio leads to the best performance, especially in terms of degradation with electromagnetic loads. To extend this analysis to larger size Nb₃Sn CICCs, we manufactured and tested, in the SULTAN facility, an ITER toroidal field (TF) cable, inserted into a thick stainless steel tube and then compacted to a high aspect ratio rectangular shape. Besides establishing a new record in Nb₃Sn CICC performances for ITER TF type cables, the very good test results confirmed that the conductor properties improve not only by lowering the void fraction and raising the cable twist pitch, as already shown during the ITER TFPRO and the EDIPO test campaigns, but also by the proper optimization of the conductor shape with respect to the electromagnetic force distribution. The sample manufacturing steps, along with the main test results, are presented here.

[en] Selected for the SSC Vendor Qualification Program, AISA started to develop SSC outer wire and cable in October 1991 with the Phase I Program which consisted of R ampersand D efforts and an initial production of 3400 kg of outer cable. This phase which was achieved in February 1992 resulted in some modifications allowing improvements of the manufacturing process used in the Phase II production of 6300 kg of outer cable. This production, concerning the wire, was achieved four months after receiving the starting NbTi alloy. And 5500 kg of outer cable were delivered to SSCL six weeks later well within the May 1st 1993, date given by SSCL as a target. This paper reports relevant results of the Phase II production and presents performance of the Phase II wire as well as those of cables manufactured during Phase I and Phase II

[en] In this paper, some of the characteristics of the new materials bearing on their utilization are examined and some of the principal barriers to application are assessed. Some of the promises and successes in applying superconductors over the past 28 years are discussed and the implications of the new discoveries from the point of view of application considered. (orig./WL)

[en] This patent describes a multifilamentary superconducting cable. It comprises: a first guide wire; a second guide wire disposed substantially parallel to the first guide wire; a first layer having mutually parallel superconducting filaments, the first layer being alternatingly passed in sequence under and over the first guide wire and the second guide wire at a predetermined oblique angle; and a second layer having a plurality of mutually parallel superconducting filaments, the layer being alternatingly passed in sequence under and over the second guide wire and the first guide wire at the predetermined oblique angle with the first and second layer alternatingly overlapping each other as the respective layers pass between the first and second guide wires

[en] Oxford Superconducting Technology (OST) is participating in the Vendor Qualification Program (VQP) for producing superconducting cable for the Outer Dipole Magnets. After a successful completion of Phase I of this VQP, OST began Phase II of the VQP. Phase II consisted of multifilament billets that utilized the process optimization improvements demonstrated during Phase I. Along with SSC Phase II, OST is currently producing wire for the Relativistic Heavy Ion Collider (RHIC) Dipole Magnets at Brookhaven National Laboratory. Thirty tonnes are completed at this time. This paper presents results from Phase II strand processing with correlations to RHIC Dipole processing