Measurements of a crenelated iron pole tip for the VLHC transmission line magnet

The Very Large Hadron Collider (VLHC) is under conceptual design in Fermilab. One option under development is a 2-Tesla warm iron 2-in-1 single turn superferric magnet built around an 80 kA superconducting transmission line. A normal-conducting test stand was built to optimize the iron lamination shape for this magnet. It uses a water- cooled copper winding to provide the 100 kA-turns needed to generate 2 Tesla fields in both 20 mm air gaps of the magnet. A magnetic measurement facility has been set up for magnetic field mapping, which includes a flat measurement coil, precision stage for coil motion and integrator. Results from a first test of the "crenelation" technique to mitigate the saturation sextupole in iron magnets are described and future plans are discussed. (5 refs)

Structure and grain growth of TiO2 nanoparticles investigated by electron and X-ray diffractions and Ta-181 perturbed angular correlations

Bare and coated TiO₂ nanoparticles with particle sizes d 100 nm after 1300 K. PAC spectra taken in the same temperature range show that with increasing temperature, the initially disordered state transforms to well-ordered rutile TiO₂. The data suggest a critical grain size of d ~10 nm for the onset of the ordering process. The spectra of coarse-grained TiO₂ are reached at a particle size d >= 30 nm. In n-TiO₂ coated with Al₂O₃ and ZrO₂ both the cores and the coatings were found to grow with increasing temperature; the cores of the coated particles, however, grow much less than those of the noncoated particles. The PAC method was used to investigate the QI in both TiO₂ cores and in the ZrO₂ coating of n-TiO₂/ZrO₂ at different temperatures. These data suggest that although the coated particles grow with temperature, the ordering process is obstructed, possibly by a solid state reaction between the TiO₂ kernels and the coatings

Structural characterisation of Fe2O3 nanoparticles

The structure of nano-crystalline Fe2O3 particles, synthesized using the microwave plasma technique, has been analysed using synchrotron based X-ray absorption spectroscopy and X-ray powder diffraction, as well as transmission electron microscopy. Furthermore, magnetic properties, the crystal structure, and the microstructures are compared and the potential model character of the samples for structure simulations is discussed