Fluidization of nanoparticle agglomerates is a promising technique to process nanoparticles. However, possible elutriation of small agglomerates may cause significant loss of bed material. To obtain the elutriation behavior under stable operation, in this study the elutriation fraction of silica nanoparticle agglomerates is measured in a vibro-fluidized bed, which is operated for several hours. Among conditions with different fluidizing gas velocities, U_g, and vibration strength, Λ, the lowest elutriation fraction measured is around 5% after 7-hour fluidization. The elutriation fraction increases significantly with U_g, while varies slightly with Λ. To help elucidating the elutriation behavior, the agglomerates at three different locations (bed surface, splash zone, and bed outlet) are sampled and their size distributions are determined. The elutriation rate constant is found to be much smaller than the literature results for ordinary particles, and the reasons are discussed in detail. Finally, an empirical correlation considering size distribution is proposed to fit the elutriation rate constant for the conditions in this study.

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Several methods of polarized neutron scattering call for a zero magnetic field (ZF) region to reduce magnetic field integral aberrations while preserving the neutron polarization. Though the design for large angle neutron scattering has been presented in various places, the design characterization and tuning has not been discussed before. In this report, the tuning procedure will be discussed with both neutron polarization transport method and utilization of fluxgate magnetometers. As a tuning procedure, polarized neutrons are sensitive to any local field distortions along all trajectories within the beam, but the process is slow. With fluxgates, the entire beam region cannot be accessed simultaneously, but very fast and precise measurements can be made in accessible regions of interest. Consequently, we would like to benchmark the usage of fluxgates as a fast tuning probe compared with polarization measurements made with neutrons. Polarization transport results for tuned ZF chambers, up to 2.25 m in length, are presented.

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The neutron Larmor diffraction technique has been implemented using superconducting magnetic Wollaston prisms in both single-arm and double-arm configurations. Successful measurements of the coefficient of thermal expansion of a single-crystal copper sample demonstrates that the method works as expected. The experiment involves a new method of tuning by varying the magnetic field configurations in the device and the tuning results agree well with previous measurements. The difference between single-arm and double-arm configurations has been investigated experimentally. We conclude that this measurement benchmarks the applications of magnetic Wollaston prisms in Larmor diffraction and shows in principle that the setup can be used for inelastic phonon line-width measurements. The achievable resolution for Larmor diffraction is comparable to that using Neutron Resonance Spin Echo (NRSE) coils. The use of superconducting materials in the prisms allows high neutron polarization and transmission efficiency to be achieved.@en