Fabrication and Testing of a Bi-2223 Test Coil for High Field NMR Magnets.

In 2005 the Committee on Opportunities in High Magnetic Fields (COHMAG) issued a challenge to develop a 30 T high-resolution NMR magnet. In response, the National High Magnetic Field Laboratory (NHMFL) is investigating all three commercially available high-temperature superconductors (HTS) including REBCO, Bi-2212 and most recently, a reinforced Bi-2223 conductor supplied by Sumitomo Electric, designated Type HT-NX. Recent investigations of Type HT-NX conductor at the NHMFL and by others suggest that operation at hoop stress above 400 MPa, and total strain above 0.7% may be feasible. We have fabricated a test coil from a single 240 m length of HT-NX. The coil was successfully operated to 19.5 T in a 14 T background field, with a total applied strain of 0.8% and coil current density of 243 A/mm2. The coil was cycled 20 times from half the design current to full current without observed degradation.

Bi-2223 Test Coils for High Resolution NMR Magnets.

Recently, significant improvement in the strain tolerance of Bi-2223 conductor has been achieved by lamination with high strength nickel alloy. The conductor, supplied by Sumitomo Electric and designated Type HT-NX, is now commercially available in lengths sufficient for manufacture of high-homogeneity solenoids. A program to fully exploit the improved conductor properties is now underway at the National High Magnetic Field Laboratory (NHMFL). Five coils are being made, the last of which is to demonstrate an NMR measurement approaching 1 GHz and 1 ppm over 10 mm volume. In so doing, we expect to demonstrate critical current fraction, and strain similar to that expected in 30 T NMR magnets. The coils will be tested inside an existing 16 Tesla large-bore background magnet at the NHMFL. The design of the NMR demonstration coil is presented first, with expected values for field, homogeneity and strain given. A technology development program is then outlined, which includes fabrication of four test coils to test various design features, develop fabrication tooling and train personnel.

A flexible neutron spectrometer concept with a new ultra-high field steady-state vertical-bore magnet.

The proposed facility explores materials under ultra-high magnetic fields. By combining the power of high fields to tune materials and of neutron scattering to probe the resulting changes down to the atomic scale, this facility will enable transformative progress in the study of quantum materials and is named for the "TITAN" subset of Greek gods to reflect this transformation. TITAN will offer DC magnetic fields up to at least 20 T. Exploiting the record brightness and bandwidth of the Second Target Station at the Spallation Neutron Source, TITAN will probe atomic-scale responses through high efficiency neutron spectroscopy up to 80 meV energy transfer, high resolution diffraction, and small angle neutron scattering. Focusing neutron optics will maximize flux on accurately positioned samples, while radial collimation and optimized shielding and detection strategies will minimize backgrounds.

A Feasibility Study of High-Strength Bi-2223 Conductor for High-Field Solenoids.

We performed a feasibility study on a high-strength Bi2-x Pb x Sr2Ca2Cu3O10-x (Bi-2223) tape conductor for high-field solenoid applications. The investigated conductor, DI-BSCCO Type HT-XX, is a pre-production version of Type HT-NX, which has recently become available from Sumitomo Electric Industries (SEI). It is based on their DI-BSCCO Type H tape, but laminated with a high-strength Ni-alloy. We used stress-strain characterizations, single- and double-bend tests, easy- and hard-way bent coil-turns at various radii, straight and helical samples in up to 31.2 T background field, and small 20-turn coils in up to 17 T background field to systematically determine the electro-mechanical limits in magnet-relevant conditions. In longitudinal tensile tests at 77 K, we found critical stress- and strain-levels of 516 MPa and 0.57%, respectively. In three decidedly different experiments we detected an amplification of the allowable strain with a combination of pure bending and Lorentz loading to ≥ 0.92% (calculated elastically at the outer tape edge). This significant strain level, and the fact that it is multi-filamentary conductor and available in the reacted and insulated state, makes DI-BSCCO HT-NX highly suitable for very high-field solenoids, for which high current densities and therefore high loads are required to retain manageable magnet dimensions.

A system of canals in semilunar menisci.

Semilunar menisci of young calves, and infants and young children were examined with the scanning electron microscope and the light microscope. Canal-like structures were noted opening onto the surface of the menisci. After filling the joints with Indian ink, ink was noted within canal-like structures deep in the substance of the tissue. The canals may play a part in the transport of fluid within the meniscus, or may carry nutrients from the synovial fluid or the blood vessels to the avascular sections of the meniscus.

Histomorphometry of iliac crest bone in 346 normal black and white South African adults.

We examined undecalcified transiliac bone samples from 346 normal black and white South African adults (age range 21-83 years) by routine histomorphometry. The results were analysed for race-, age- and sex-dependent characteristics of trabecular microstructure (bone volume, trabecular thickness, trabecular number, trabecular separation) and static bone turnover variables (osteoid surface, osteoid volume, osteoid thickness, erosion surface). Trabecular thickness was greater in blacks than in whites, and bone volume was greater in black males, but not in black females, than in their white counterparts. Values for osteoid surface, volume and thickness, and for erosion surface were greater in blacks than in whites. Age-related changes were: a decline in bone volume in all race/sex groups; a decline in trabecular thickness in all groups except black males; a decline in trabecular number in all groups except black females; and a rise in trabecular separation in all groups except black females. There was an increase with age in osteoid surface in all groups except white males, in osteoid volume in all groups, and in erosion surface in blacks only. When correcting for age there were no sex-dependent differences in microstructure but values of some osteoid variables were greater in males than in females. If the greater osteoid and erosion values in blacks reflect greater bone turnover, then trabecular bone in blacks would be renewed more frequently, be subjected to fewer loading cycles and be less prone to fatigue failure. Blacks may thus have trabecular bone of better quality and sturdier microarchitecture. These features could contribute to the lower spontaneous fracture rate in blacks.