The range of validity of the anomalous diffraction approximation to electromagnetic scattering by a sphere.
The ranges of refractive index and particle size over which the anomalous diffraction approximation is valid to within 15%, 50%O, and 100% are mapped. The approximation is found to have a broader range of applicability for the extinction efficiency than the Rayleigh-Gans approximation. The large range of validity explains the success of schemes for determining particle size distributions of spheres from extinction measurements based on analytic inversions of formulas containing the approximation.
Aerosol studies by light scattering. V. Preparation and particle-size distribution of aerosols consisting of particles exhibiting high optical absorption
Aerosols consisting of solid spheres have been prepared in a newly designed generator by two-stage evaporation-condensation of vanadium pentoxide in a furnace capable of operating up to 1500”. Nuclei were prepared by evaporation of aluminum a t 1000”, condensation to an aluminum aerosol, and subsequent burning in oxygen to A1203. The particle size distribution of the aerosols was determined by analysis of the angular distribution of the polarization of the scattered light. The special feature of this work resides in the high optical absorption of aerosol particles a t the blue end of the visible spectrum (comparable to that of metals) and the low absorption a t the red end (comparable to dielectrics). By considering several wavelengths, the very different scattering data on the same physical system led to size distributions which agreed with each other. The uniqueness of these results was explored with the aid of error contour maps.
In-House Industrial Production of the Superconducting Conductor for the 43 T Hybrid Magnet of LNCMI-Grenoble
The hybrid magnet being built at LNCMI-Grenoble is based on the combination of resistive inserts, made up of Bitter and polyhelix coils, with a large bore superconducting outsert. It will produce, in the first step, an overall continuous magnetic field of 43 T in a 34 mm warm bore aperture. The superconducting coil will provide a nominal magnetic field of 8.5 T in a 1.1 m cold bore diameter. It relies on the novel development of an Nb-Ti/Cu Rutherford Cable On Conduit Conductor (RCOCC) cooled down to 1.8 K by a bath of superfluid helium pressurized at 1200 mbar. After a brief reminder of the specificity of hybrid magnets, namely the strong electromechanical coupling between resistive and superconducting coils, the main requirements of the RCOCC for efficient and reliable magnet operation are given. The test and validation phases prior to the industrial production of the RCOCC are reported, including the trial production of the ½ hard-drawn (H02 cold-worked) Cu-Ag 0.05% hollow stabilizer in continuous lengths of 325 m. The novelty of the RCOCC development concerns the assembly and the induction soft-soldering of the Rutherford cable on the Cu-Ag hollow stabilizer allowing a strict control of the interstrand contact resistance. Studies, developments, and the integration of the industrial production line at LNCMI-Grenoble are presented together with the result of the production of all RCOCC unit lengths.