137403613
Design of a Probe for Strain Sensitivity Studies of Critical Current Densities in SC Wires and Tapes
The design of a variable-temperature probe used to perform strain sensitivity measurements on LTS wires and HTS wires and tapes is described. The measurements are intended to be performed at liquid helium temperatures (4.2 K). The wire or tape to be measured is wound and soldered on to a helical spring device, which is fixed at one end and subjected to a torque at the free end. The design goal is to be able to achieve {+-} 0.8 % strain in the wire and tape. The probe is designed to carry a current of 2000A.
116294626
Nb3Sn cable development for the 11 T dipole demonstation model
Fermilab (FNAL) and CERN have started the development of 11 T 11-m long Nb{sub 3}Sn dipoles to replace a number of LHC NbTi dipoles and free space for cold collimators in the LHC DS areas. An important step in the design of these magnets is the development of the high aspect ratio Nb{sub 3}Sn cable to achieve the nominal field of 11 T at the nominal LHC operating current of 11.85 kA at 1.9 K with 20% margin. Keystoned cables with 40 and 41 strands with and without a stainless steel core were made out of hard Cu wires and Nb{sub 3}Sn RRP strand of 0.7 mm nominal diameter. The cable optimization process was aimed at achieving both mechanical stability and minimal damage to the delicate internal architecture of the Restacked-Rod-Process (RRP) Nb3Sn strands with 127 restack design to be used in the magnet short models. Each cable was characterized electrically for transport properties degradation at high field and for low field stability, and metallographically for internal damage.
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.
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.
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.
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.
14255912
Measurements of charmless B decays related to alpha at BaBar
We report recent measurements of the CKM angle {alpha} using data collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. In addition to improved constraints on {alpha} from the decays B{sup {+-}} {yields} {rho}{sup {+-}}{rho}{sup 0}, we also present preliminary results of neutral and charged B meson decays to K{sub 1}(1270){pi} and K{sub 1}(1400){pi} and its impact on the estimate for the CKM angle {alpha} based on time-dependent analysis of CP-violating asymmetries in B{sup 0} {yields} a{sub 1}(1260){sup {+-}} {pi}{sup {-+}}. Moreover we report the first observation of the decay B {yields} a{sub 1}(1260){sup {+-}}a{sub 1}(1260){sup {-+}}; this mode can be used, in principle, to provide an independent measurement of {alpha}.