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  • 1
    Electronic Resource
    Electronic Resource
    Nb-added high-coercivity Nd-Fe-B melt-spun ribbon with high remanence : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6477-6479 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of composition and additives on the microstructures and magnetic properties of Nd-Fe-B melt-spun ribbons were studied. Experimental results have revealed that homogeneous grain structure with fine grain size was obtained on composition close to 2-14-1 stoichiometry with additives. It was also found that Nb was very effective in increasing both remanence and coercivity in a Nd-Fe-B melt-spun ribbon. A high-energy product of 151.2 kJ/m3 (19.0 MGOe) was obtained from an isotropic (Nd0.5Pr0.5)12Fe72Co8B6Nb2 melt-spun ribbon with a remanence of 0.926 T and a coercivity exceeding 1200 kA/m (∼15 kOe).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349905
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  • 2
    Electronic Resource
    Electronic Resource
    Poloidal rotation in tokamaks with large electric field gradients (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 159-166 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The ion poloidal flow velocity near the plasma edge in a tokamak has been calculated by extending neoclassical theory to include orbit squeezing, which is the reduction of the ion banana widths due to radial electric field shear. The pressure gradient-driven ion parallel flow is reduced by orbit squeezing, and then no longer cancels the diamagnetic flow in its contribution to poloidal flow. This allows the poloidal flow velocity to be a significant fraction of the ion diamagnetic velocity, which can be much larger than the standard neoclassical value (proportional to the ion temperature gradient). Equations for determining the poloidal flow and radial electric field profiles self-consistently are given. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871105
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  • 3
    Electronic Resource
    Electronic Resource
    Crystallographic and magnetic properties of NdFe10.7TiM0.3(M=B, Ti) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5516-5518 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: NdFe10.7TiM0.3(M=B, Ti) has been studied with x-ray diffraction, Mössbauer spectroscopy, and a vibrating sample magnetometer. The alloys were prepared by arc-melting under an argon atmosphere. The NdFe10.7TiB0.3 exhibits a pure single phase, whereas the NdFe10.7Ti1.3 contains some α-Fe, from x-ray and Mössbauer measurements. The NdFe10.7TiB0.3 has the ThMn12-type tetragonal structure with a0=8.587 A(ring) and c0=4.788 A(ring). The Curie temperature (TC) is 570 K from Mössbauer spectroscopy performed at various temperatures ranging from 13 to 770 K. Each spectrum below TC was fitted with five subspectra of Fe sites in the structure (8i1, 8i2, 8j1, 8j2, and 8f ). The area fraction of the subspectra at room temperature are 16.4%, 8.2%, 14.8%, 21.3%, and 39.3%, respectively. Magnetic hyperfine fields for the Fe sites decrease on the order of Hhf(8i)(approximately-greater-than)Hhf(8j)(approximately-greater-than)Hhf(8f ). The average hyperfine field Hhf(T) of the NdFe10.7TiB0.3 shows a temperature dependence of [Hhf(T)−Hhf(O)]/Hhf(O)=−0.39(T/TC)3/2 & −0.17(T/TC)5/2 for T/TC〈0.7, indicative of spin-wave excitation. Annealing the alloy at around TC for 60 min resulted in a two phase microstructure consisting of a ThMn12-type structure and α-Fe. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361851
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  • 4
    Electronic Resource
    Electronic Resource
    Nanocrystalline Nd12Fe80B6Nb1Ga1 melt-spun ribbon with textured surface (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4756-4758 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In Nd-Fe-B melt-spun ribbon, Ga addition is found to be effective for the orientation of c axis of 2-14-1 grains normal to the ribbon plane even at high wheel surface velocity. A Nd12Fe80B6Nb1Ga1 melt-spun ribbon quenched with optimum wheel surface velocity was found to have textured structure on the free-side surface. Furthermore, this melt-spun ribbon was composed of fine grains of about 30 nm in size which is believed to be enough to provoke intergrain exchange interaction. The remanence and energy product of the field aligned powder of this melt-spun ribbon was about 7% and 20% higher than those of the not-aligned powder, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355904
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  • 5
    Electronic Resource
    Electronic Resource
    Thermomagnetic analysis of NdFeB melt-spun alloys with low Nd content (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4133-4135 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The phase transformation of NdFeB melt-spun alloys with low Nd content of 4–8 at. % was investigated by thermomagnetic analysis and x-ray diffractometry. Experimental results have shown that the metastable Nd2Fe23B3 compound formed in the alloys is considered to be transformed to Nd2Fe23B3+α-Fe+Fe3B in the temperature range of 550–690 °C, α-Fe+Fe3B+Nd1+eFe4B4 in the temperature range of 690–730 °C and finally α-Fe+Nd1+eFe4B4 above 840 °C. From the results, it has been concluded that Nd2Fe14B is not formed from metastable Nd2Fe23B3. On the other hand, the melt-spun alloy of Nd2Fe23B3 (∼Nd7.1Fe82.1B10.7) annealed under optimum conditions has been found to be composed of α-Fe, Fe3B, and Nd2Fe14B phases. The alloy has a coercivity comparable to Fe3B-based Nd4Fe77B19 and relatively high-energy product of about 71.6 kJ/m3 (∼9 MG Oe). © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359501
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  • 6
    Electronic Resource
    Electronic Resource
    High-spectral-resolution pulsed photoluminescence study of molecular-beam-epitaxy-grown GaAs/AlxGa1−xAs multi-quantum-well structures using a very-low-power tunable pulsed dye laser (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1740-1744 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultralow-power, high-resolution, pulsed-laser photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies were carried out in molecular-beam-epitaxial GaAs/AlxGa1−xAs multi-quantum-well structures at 5 K. Fine structures were observed for the first time in the PLE spectra, both in the heavy-hole and light-hole excitonic regions. Most of the fine structures are considered to arise from monolayer fluctuations in the thicknesses of the GaAs wells. Dramatic changes in the line shapes and the peak positions of the PL and PLE spectra were observed by applying selective PL detection and excitation spectroscopic techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337268
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  • 7
    Electronic Resource
    Electronic Resource
    Rubbed polyimide films studied by scanning force microscopy (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2218-2219 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surfaces of rubbed polyimide films for aligning liquid crystal have been studied by atomic force microscopy. The unrubbed films consisted of randomly distributed polyimide clusters of different sizes. On the rubbed surface, however, the clusters are aligned in long chains along the rubbing direction. The cluster chains were separated by about 100 nm for small rubbing strength. For higher strength the cluster chains coalesced into wider ones. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113172
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  • 8
    Electronic Resource
    Electronic Resource
    Improved confinement and stability in the DIII-D tokamak obtained through modification of the current profilef| (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 2532-2539 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Improvement in both the energy confinement time and the achievable value of normalized beta is obtained by modifying the current density profile from the relatively broad shape obtained in standard tokamak discharges to a more peaked shape. The peaked current profile is produced with either a rapid negative ramp in the total plasma current or a rapid increase in the discharge elongation. Discharges have been obtained with βN=β/(I/aB)=6% mT/MA simultaneously with total energy confinement time two times the value predicted by L-mode scaling relations. Up to a factor of 1.8 improvement in the normalized thermal energy confinement time, τth/Ip, has been obtained in both L-mode and H-mode discharges. It is shown that the increase in confinement can be attributed to a local decrease in the thermal diffusivity that is correlated with a local increase in the poloidal magnetic field and the magnetic shear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860740
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  • 9
    Electronic Resource
    Electronic Resource
    Poloidal viscosity and radial currents (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 278-279 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Considerable doubt is cast on the L- to H-mode transition mechanism proposed by Shaing [Phys. Rev. Lett. 63, 2369 (1989)]. Contrary to his assertion, a consistent application of the momentum balance equations shows that ion orbit loss current does not drive large poloidal rotation in tokamaks, in steady state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860445
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  • 10
    Electronic Resource
    Electronic Resource
    Ion-temperature-gradient-driven modes in neoclassical regime (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 1179-1187 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A reduced set of neoclassical fluid equations, consisting of the parallel ion flow velocity v(parallel), the generalized potential F, the ion pressure p, and the parallel ion heat flow q(parallel), is derived. The resultant equations are the extension of reduced fluid equations derived from Braginskii equations with the high collisionality to the equations relevant to a fusion plasma with low to intermediate collisionality. The linear ηi mode dynamics is reinvestigated by using the resultant model equations. The effects of the perpendicular compressibility in the ion pressure response, the parallel heat flow, and the neoclassical viscosity are analyzed both analytically and numerically. It is stressed that the closure condition of neoclassical viscosity changes the sign of energy dissipation and seriously affects the stability of ηi modes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860908
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