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  • 1
    Electronic Resource
    Electronic Resource
    Chemical equilibrium in simple fluids: Solvent density dependence of the dimerization equilibrium of 2-methyl-2-nitrosopropane in argon and xenon (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 3824-3829 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied the dimerization equilibrium of 2-methyl-2-nitrosopropane (MNP) at 60 and 35 °C in argon and xenon up to densities about twice the critical density of the solvent. With an increase in the solvent density, the dimerization equilibrium constant at 60 °C decreases in the low-density region, whereas it increases in the high-density region. The inversion of the density dependence occurs around ρr(approximately-equal-to)0.8 in argon and ∼1.4 in xenon, where ρr means the density reduced by the critical density of the solvent fluid. The equilibrium constant in xenon at 35 °C increases with increasing solvent density in the low-density region (ρr〈∼0.5), while it decreases in the medium-density region (0.5〈ρr〈1.5). The equilibrium constant in argon at 35 °C has a similar density dependence to that at 60 °C. The internal energy change for the dimerization shows a large density dependence in the low-density region of xenon, while it changes little with density in argon. The theoretical calculation by the Percus–Yevick (PY) approximation for a simple reaction model gives a poor result for the density dependence of the equilibrium constant, although the temperature dependence of the equilibrium constant is reproduced qualitatively. The calculation for a more realistic model including the molecular anisotropy of MNP suggests that the density dependence at the low-density limit is sensitive to the interaction model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461887
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  • 2
    Electronic Resource
    Electronic Resource
    Chemical equilibrium in fluids from the gaseous to liquid states: Solvent density dependence of the dimerization equilibrium of 2-methyl-2-nitrosopropane in carbon dioxide, chlorotrifluoromethane, and trifluoromethane (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 3085-3091 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied the dimerization equilibrium of 2-methyl-2-nitrosopropane in carbon dioxide (CO2), chlorotrifluoromethane (CClF3), and trifluoromethane (CHF3) at 60 °C from the gaseous to liquid states. The dimerization equilibrium constants are not monotone functions of the solvent density in all solvent fluids. The density dependence of the equilibrium constant shows two inversions: The equilibrium constants in CO2 and CHF3 increase with increasing solvent density up to ρr(approximately-equal-to)0.3, where ρr is the reduced density by the critical density of solvent, whereas the equilibrium constant in CClF3 shows little dependence on the solvent density in this density region. From ρr(approximately-equal-to)0.3 to about 1.4, the equilibrium constants decrease with increasing solvent density. In the higher-density region, the equilibrium constants increase again. We measured the equilibrium constants in CClF3 and CHF3 at 35 °C, and obtain the density dependence of the equilibrium constant which is almost the same as that at 60 °C. The effects of the temperature and the solvent species on the equilibrium constant are larger in the low-density region than in the high-density region. The differences between the low- and high-density regions suggest that the energetic factor is dominant in the low-density region, and that the packing effect is dominant in the high-density region. The experimental results are qualitatively reproduced by a simple reaction model where two spherical molecules dimerize in a fluid composed of spherical molecules, although the reaction model overestimates the equilibrium constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461953
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  • 3
    Electronic Resource
    Electronic Resource
    Keto-enol tautomeric equilibrium of acetylacetone in trifluoromethane near the critical temperature (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 5243-5244 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The keto-enol tautomeric equilibrium of acetylacetone in trifluoromethane were studied at 300±0.5 K (1 K above the critical temperature) from 130 kg m−3 to 800 kg m−3 by using FT–NMR. No anomalous behavior near the critical point has been found within the experimental error. The equilibrium constant decreases rapidly in the low density region (〈200 kg m−3) and the decreasing rate reduces with increasing the density of solvent. The density dependence is interpreted by the hydrogen bonding between trifluoromethane and acetylacetone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460531
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  • 4
    Electronic Resource
    Electronic Resource
    Experimental test of the radial force balance equation in the compact helical system (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 1-4 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental test of the radial force balance equation was done in the Compact Helical System Heliotron/Torsatron [S. Okamura et al. Nucl. Fusion 39, 1337 (1999)]. A radial electric field is measured with a heavy ion beam probe, while plasma rotation and drift velocity of fully ionized carbon are measured with charge exchange spectroscopy. The two measurements agree with each other to within 10% of the radial electric field in a wide range of electron densities of 0.3–2.0×1019 m−3. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1331097
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  • 5
    Electronic Resource
    Electronic Resource
    Electron cyclotron resonance heating by strong monochromatic wave in nonuniform magnetic field (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 834-841 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Numerical studies are made on dynamics of electrons under electron cyclotron resonance heating (ECRH) by a strong monochromatic wave in a nonuniform magnetic field. The response of the electrons is described in terms of gains in energy and magnetic moment. These expressions are employed to define a response function which connects the velocity distributions of electrons before and after heating in a wide range of conditions. The response function is applied to calculate the velocity distribution of cold electrons which stream up the magnetic slope and are heated at the resonance. This configuration simulates a possible scheme for controlling an inward flux of cold electrons in diverter regions of tori and in mirror ends by mirror reflection enhanced by ECRH. The velocity distribution shows wing-like structures which are not expected from diffusion equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870742
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  • 6
    Electronic Resource
    Electronic Resource
    Experimental study of the bifurcation nature of the electrostatic potential of a toroidal helical plasma (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 4152-4183 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The bifurcation nature of the electrostatic structure is studied in the toroidal helical plasma of the Compact Helical System (CHS) [K. Matsuoka et al., Proceedings of the 12th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Nice, 1988 (International Atomic Energy Agency, Vienna, 1989), Vol. 2, p. 411]. Observation of bifurcation-related phenomena is introduced, such as characteristic patterns of discrete potential profiles, and various patterns of self-sustained oscillations termed electric pulsation. Some patterns of the electrostatic structure are found to be quite important for fusion application owing to their association with transport barrier formation. It is confirmed, as is shown in several tokamak experiments, that the thermal transport barrier is linked with electrostatic structure through the radial electric field shear that can reduce the fluctuation resulting in anomalous transport. This article describes in detail spatio-temporal evolution during self-sustained oscillation, together with correlation between the radial electric field and other plasma parameters. An experimental survey to find dependence of the temporal and spatial patterns on plasma parameters is performed in order to understand systematically the bifurcation property of the toroidal helical plasma. The experimental results are compared with the neoclassical bifurcation property that is believed to explain the observed bifurcation property of the CHS plasmas. The present results show that the electrostatic property plays an essential role in the structural formation of toroidal helical plasmas, and demonstrate that toroidal plasma is an open system with a strong nonlinearity to provide a new attractive problem to be studied. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1290483
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  • 7
    Electronic Resource
    Electronic Resource
    Inward turbulent particle transport in a helical plasma heated by neutral beam injection (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 4035-4041 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In neutral-beam-injection (NBI) heated plasmas of the Compact Helical System (CHS) heliotron/torsatron [K. Matsuoka et al., Plasma Physics and Controlled Nuclear Fusion Research, 1988 (International Atomic Energy Agency, Vienna, 1989), Vol. 2, p. 441], inward turbulent particle flux is observed at a particular radial location near the plasma edge. The observed reversal of the particle flux is connected to the change in the cross-phase between electron density and poloidal electric field fluctuations. This phenomenon is observed in the parameter regime of low collisionality at the electron temperature Te〉15 eV, electron density ne〈3×1018 m−3, which approximately corresponds to the effective collision frequency normalized by the transit frequency of a circulating particle ν*(approximately-less-than)1. The large inward particle flux ((approximately-greater-than)1×1020 m−2 s−1) correlates with the positive shear of the radial electric field Er′ ((approximately-greater-than)1×106 V m−2), but does not have clear correlation with the radial electric field Er and the curvature Er″. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1387267
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  • 8
    Electronic Resource
    Electronic Resource
    Theoretical analysis of thermal dike supported by electron cyclotron resonance heating (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3986-3995 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermal dike is a new concept for controlling energy transport carried by electrons along open magnetic field lines by enhancing mirror-reflection with assistance of electron cyclotron resonance heating (ECRH). Quantitative analyses are made to evaluate merits of thermal dike and to clarify requirements for efficient use of it. Heating response function is applied for trajectory analyses of electrons streaming through the ECRH zone. Substantial power gain is obtained under a configuration with a high mirror ratio between the reflection point and the resonance point and with a large scale length of the magnetic gradient in the resonance zone. Thermal dike is shown to be beneficial both in tandem mirrors and in diverters in tori. Discussions are made also on a basic experiment program of thermal dike in the GAMMA 10 tandem mirror.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870914
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  • 9
    Electronic Resource
    Electronic Resource
    Ion cyclotron range of frequency heating experiments on the large helical device and high energy ion behavior : The 42nd annual meeting of the division of plasma physics of the American Physical Society and the 10th international congress on plasma physics (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 2139-2147 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion cyclotron range of frequency (ICRF) heating experiments on the Large Helical Device (LHD) [O. Motojima et al. Fus. Eng. Des. 20, 3 (1993)] achieved significant advances during the third experimental campaign carried out in 1999. They showed significant results in two heating modes; these are modes of the ICH-sustained plasma with large plasma stored energy and the neutral beam injection (NBI) plasma under additional heating. A long-pulse operation of more than 1 minute was achieved at a level of 1 MW. The characteristics of the ICRF heated plasma are the same as those of the NBI heated plasma. The energy confinement time is longer than that of International Stellarator Scaling 95. Three keys to successful ICRF heating are as follows: (1) an increase in the magnetic field strength, (2) the employment of an inward shift of the magnetic axis, (3) the installation of actively cooled graphite plates along the divertor legs. Highly energetic protons accelerated by the ICRF electric field were experimentally observed in the energy range from 30 to 250 keV and the tail temperature depended on the energy balance between the wave heating and the electron drag. The transfer efficiency from the high energy ions to the bulk plasma was deduced from the increase in the energy confinement time due to the high energy ions in the lower density discharge, which agrees fairly well with the result obtained by the Monte Carlo simulation. The transfer efficiency is expected to be 95% at an electron density of more than ne=5.0×1019 m−3 even in the high power heating of 10 MW. The accumulation of impurities, e.g., FeXVI and OV was not observed in high rf power and long pulse operation. The well-defined divertor intrinsic to LHD is believed to be useful in reducing the impurity influx. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1354152
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  • 10
    Electronic Resource
    Electronic Resource
    Oxidative Regeneration of Spent Molybdate and Tungstate Hydrotreating Catalysts (1994)
    s.l. : American Chemical Society
    Energy & fuels 8 (1994), S. 435-445 
    Details
    ISSN: 1520-5029
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ef00044a023
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