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Magnetic Levitation To Characterize the Kinetics of Free-Radical Polymerization
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Probing disorder in pyrochlore oxides using in situ synchrotron diffraction from levitated solids–A thermodynamic perspective
Abstract Pyrochlore, an ordered derivative of the defect fluorite structure, shows complex disordering behavior as a function of composition, temperature, pressure, and radiation damage. We propose a thermodynamic model to calculate the disordering enthalpies for several RE 2 Zr 2 O 7 (RE = Sm, Eu, Gd) pyrochlores from experimental site distribution data obtained by in situ high temperature synchrotron X-ray diffraction. Site occupancies show a gradual increase in disorder on both cation and anion sublattices with increasing temperature and even greater disorder is achieved close to the phase transition to defect fluorite. The enthalpy associated with cation disorder depends on the radius of the rare earth ion, while the enthalpy of oxygen disordering is relatively constant for different compositions. The experimental data support trends predicted by ab initio calculations, but the obtained enthalpies of disordering are less endothermic than the predicted values. Thermal expansion coefficients are in the range (8.6–10.8) × 10 −6 K −1 . These new experimental determinations of defect formation energies are important for understanding the stability of pyrochlore oxides and their disordering mechanisms, which are essential in the context of their potential applications in nuclear waste management and other technologies.
Millimeter-wave radiometer diagnostics of harmonic electron cyclotron emission in the Levitated Dipole Experiment
A 110/137 GHz radiometer pair with collimated antenna pattern is being used to diagnose optically thin harmonic electron cyclotron emission from hot electrons in LDX. Signal levels of 0.1-1 keV and 110/137 ratios of 2-4 stationary with ECRH power have been observed. The large plasma core magnetic field gradient causes all relevant harmonics to be simultaneously viewed over a <(k,B) angular range of 0 deg. - 90 deg. representing a unique geometry for interpretation of ECE in terms of hot electron temperature and density.
Confinement of electron plasma by levitating dipole magnet
A recent experiment on the Ring Trap 1 device has demonstrated long-term (exceeding 300 s) confinement of non-neutral (pure electron) plasma in a dipole magnetic field; particles diffuse inward, steepening the density gradient and self-organizing into a stable vortex structure [Z. Yoshida et al., Phys. Rev. Lett. 104, 235004 (2010)]. In this study, the internal structures of the plasma are experimentally investigated, and it is shown that the observations are consistent with rigidly rotating charged particle clump. The radial profiles of electrostatic potential and electron density consistently show that the drift velocity has homogeneous angular frequency in the confinement region. The electrostatic fluctuations also rotate rigidly with a phase velocity that agrees with the drift velocity. The magnetospheric system should have a wide application in confining single-species and even multiple-species charged particles.
Classical trajectory Monte Carlo simulations of particle confinement using dual levitated coils
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The solidification products of levitated Fe83B17 studied by high-energy x-ray diffraction
Detailed high-energy x-ray diffraction studies were performed to gain insight into the evolution of phase formation in undercooled Fe 83 B 17 and the mechanism for the stabilization of face-centered cubic (fcc) Fe in the presence of Fe 23 B 6 . Fe 83 B 17 solidifies directly into either the equilibrium Fe 2 B + Fe phases or the metastable Fe 23 B 6 + Fe phases. When formed, the metastable Fe 23 B 6 phase either rapidly transforms into the equilibrium Fe 2 B phase within the solidification plateau or can persist down to ambient temperature. Here, we detail these different solidification behaviors in a set of thermal cycles taken from one sample and demonstrate the absence of a direct correlation with cooling rate and thermal history. We show that the coherent growth of Fe 23 B 6 and fcc Fe suppresses the allotropic transition from fcc Fe to bcc Fe. The temperature evolution of the phase fractions and lattice parameters is also presented.
Tunable Stable Levitation Based on Casimir Interaction between Nanostructures
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Structure of Ba-Ti-Al-O glasses produced by aerodynamic levitation and laser heating
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Search for Composite Dark Matter with Optically Levitated Sensors
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Decentralized PID Control Design for Magnetic Levitation Systems Using Extremum Seeking
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Dissipative mode filtration in a “levitating” neutron flux
In experiments [1–4], where a flux of neutrons is injected into a horizontal channel, the output flux structure proves to be a nonmonotonic function of the vertical coordinate. This flux evolution is explained by the absorption of neutrons in the floor material.
Bearing-less Centrifugal Pump (non-levitated, non-electromagnetic)
3D printing design documents for a bearing-less centrifugal water pump comprised of an impeller rotor enclosing a permanent magnet which is driven by a second permanent magnet rotated by an electric motor.
Coherent control of a single nitrogen-vacancy center spin in optically levitated nanodiamond
Here, we report the first observation, to the best of our knowledge, of electron spin transients in single negatively charged nitrogen-vacancy (NV - ) centers, contained within optically trapped nanodiamonds, in both atmospheric pressure and low vacuum. It is shown that, after an initial exposure to low vacuum, the trapped nanodiamonds remain at temperatures near room temperature even in low vacuum. Furthermore, the transverse coherence time of the NV - center spin, measured to be T 2 =101.4 ns, is robust over the range of trapping powers considered in this study.
Regular oscillations and random motion of glass microspheres levitated by a single optical beam in air: Publisher’s note
The publisher’s note amends a recent publication [Opt. Express 24(3), 2850–2857 (2016)] to include Acknowledgments.