108531516
Critical currents of YBCO tapes and Bi-2212 wires at different temperatures and magnetic fields
Design studies for the cooling channel of a Muon Collider call for straight and helical solenoids generating field well in excess of the critical fields of state of the art Low Temperature Superconductors (LTS) such as Nb{sub 3}Sn or NbTi. Therefore, High Temperature Superconductors (HTS) will need to be used for the manufacturing of all or certain sections of such magnets to be able to generate and withstand the field levels at the cryogenic temperatures required by the new machine. In this work, two major High Temperature Superconductors - Bi2212 round wires and YBCO coated conductor tapes - are investigated to understand how critical current density of such conductors scales as a function of external field and operating temperature. This is vital information to make conductor choices depending on the application and to proceed with the design of such magnets.
6125992
Design of a Probe for Strain Sensitivity Studies of Critical Current Densities in Superconducting Wires
The critical current density of brittle superconducting wires used in high field magnets is very sensitive to axial strain. An accurate measurement of this strain dependence at various magnetic fields and temperatures is critical for magnet design and operation. A number of methods and techniques have been used, which generally fall into either the monotonic axial loading or bending spring techniques. The design of a variable-temperature probe to perform strain sensitivity measurements in Helium of both LTS and HTS wires is herein described. The sample is wound and soldered onto a helical Walters' spring device, which is fixed at one end and subjected to a torque at the free end. Both Ti-6Al-4V and CuBe were used as materials for the Walters' spring. Two concentric copper tubes act dually as 2000 A current and 60 Nm torque carriers. The torque is generated via a worm-gear setup and transmitted to the sample through the inner tube and spring assembly.
34735080
Development of Rutherford-Type Cables for High Field Accelerator Magnets at Fermilab
Fermilab's cabling facility has been upgraded to a maximum capability of 42 strands. This facility is being used to study the effect of cabling on the performance of the various strands, and for the development and fabrication of cables in support of the ongoing magnet R&D programs. Rutherford cables of various geometries, packing factors, with and without a stainless steel core, were fabricated out of Cu alloys, NbTi, Nb3Al, and various Nb3Sn strands. The parameters of the upgraded cabling machine and results of cable R&D efforts at Fermilab are reported.
135206500
Study of YBCO tape anisotropy as a function of field, field orientation and operating temperature
Superconducting magnets with magnetic fields above 20 T will be needed for a Muon Collider and possible LHC energy upgrade. This field level exceeds the possibilities of traditional Low Temperature Superconductors (LTS) such as Nb{sub 3}Sn and Nb{sub 3}Al. Presently the use of high field high temperature superconductors (HTS) is the only option available for achieving such field levels. Commercially available YBCO comes in tapes and shows noticeable anisotropy with respect to field orientation, which needs to be accounted for during magnet design. In the present work, critical current test results are presented for YBCO tape manufactured by Bruker. Short sample measurements results are presented up to 14 T, assessing the level of anisotropy as a function of field, field orientation and operating temperature.
123519490
BSCCO-2212 Wire and Cable Studies
BSCCO-2212 round wires and cables are being studied for possible use in very high field magnets (>; 25 T) within the multi-Lab Very High Field Superconducting Magnet Collaboration (VHFSMC). Billets produced by Oxford Superconducting Technology were used to make Rutherford-type cables of various geometries. The effect of the cable parameters was measured on the extracted strand performance and deformation. Transport properties were measured at 4.2 K in fields up to 14 T for the extracted strands across the edges, and compared with as-received round wire. The same wire used in the cables was also deformed by flat rolling to reproduce the deformation seen by the round strand when formed into a Rutherford cable. After heat treatment, rolled samples were characterized for transport properties and results compared to those obtained for strands extracted from the cables. Finally cables were tested at 4.2 K and self-field using a superconducting transformer and results compared to those of the extracted strands.
124128361
Branching Fractions in B0 Meson Decays to a1+-(1260) pi-+ and a1+-(1260)K-+