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  • PANGAEA  (162)
  • Springer  (15)
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  • 1
    Electronic Resource
    Electronic Resource
    Addition of HCl to a Cluster-Bound Vinylidene Ligand: Preparation and Structure of Ru5(μ3-SMe)(μ3-CMe)(μ-Cl)(μ-SMe)(μ-PPh2)2(CO)9·PhMe (2000)
    Springer
    Journal of cluster science 11 (2000), S. 79-86 
    Details
    ISSN: 1572-8862
    Keywords: vinylidene ; ruthenium ; dicarbide ; acetylide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Addition of aqueous HCl to Ru5(μ 3-C=CH2)(μ-SMe)2(μ-PPh2)2(CO)10 afforded the structurally characterized carbyne complex Ru5(μ 3-SMe)(μ 3-CMe)(μ-Cl)(μ-SMe)(μ-PPh2)2(CO)9, formed by addition of H to the vinylidene ligand; a Cl atom bridges an Ru–Ru bond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009056513504
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Particle saturation of the outer zone: A nonlinear model (1974)
    Springer
    Astrophysics and space science 29 (1974), S. 233-242 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Properties of the steady state and transient behavior of geomagnetically trapped radiation are analyzed by means of phenomenological equations that concisely summarize the operative dynamical processes. The equations provide for a realistic coupling between electromagnetic wave energy, particle intensity, and pitch-angle anisotropy in the context of the outer zone. Applications include magnetospheric enforcement of a limit on stably trapped particle flux. the smooth transition between weak pitch-angle diffusion and strong diffusion, parasitic particle precipitation by natural and man-made radio signals, natural and artificial injections of trapped radiation, and the consequences of magnetospheric cold-plasma injection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00642726
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Particle lifetimes in strong diffusion (1974)
    Springer
    Astrophysics and space science 31 (1974), S. 37-42 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mean lifetime τ of a particle distribution, driven to isotropy by intense pitch-angle diffusion, is calculated by analytical means for conditions applicable to the Earth's magnetosphere. The resulting algebraic expressions reduce to τ≈[64La/35vα c 2 (1−η)] in the limit of a small equatorial loss cone (half-angle α c ), wherev is the particle speed,L is the magnetic shell parameter,a is the radius of the Earth, and η is the particle albedo from the atmosphere at either foot of the field line. Distinction is made in the full expressions for τ between complete isotropy (caused by strong pitch-angle diffusion all along the field line) and incomplete isotropy (caused by strong diffusion that is localized at the magnetic equator) over the upward hemisphere in velocity space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00642599
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of drift-resonance broadening on radial diffusion in the magnetosphere (1975)
    Springer
    Astrophysics and space science 36 (1975), S. 455-458 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the quasilinear theory of magnetospheric radial diffusion caused by fluctuating electrostatic (E) or magnetic (B) fields, the diffusion coefficientD LLis proportional to the spectral density of E or B at the particle drift frequency Ω3/2π. Since Ω3 varies withL at fixedM andJ (adiabatic invariants), the drift resonance ω=Ω3 can be maintained only transiently, and therefore is not perfectly sharp. Its bandwidth Δω* is approximately (16πD LL /L 2Ω3)1/3Ω3. In magnetospheric radial diffusion caused mainly by electrostatic fluctuations, the value of Δω*Ω3 typically exceeds 0.4 for particle energiesE≲40 keV. However, the numerical value ofD LLis correctly given (within 1% in all cases) by quasilinear theory because the spectrum of E is rather flat at resonance frequencies for which the bandwidth is an appreciable fraction of Ω3. (Numerical conclusions are based on a quasilinear model forD LLused successfully by Cornwall in 1972.)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645267
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Quasi-exospheric heat flux of solar-wind electrons (1976)
    Springer
    Astrophysics and space science 39 (1976), S. 65-73 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Density, bulk-velocity, and heat-flow moments are calculated for truncated maxwellian distributions representing the cool and hot populations of solar-wind electrons, as realized at the base of a hypothetical exosphere. The electrostatic potential is thus calculated by requiring charge quasineutrality and the absence of electrical current. Plasma-kinetic coupling of the cool-electron and proton bulk velocities leads to an increase in the electrostatic potential and a decrease in the heat-flow moment. If the velocities differ by the Alfvén speed along the magnetic field, for example, the potential rises to 72.6 V and the heat flux falls to 2.72×10−2 erg cm−2 s−1. In each case the heat flux is carried mainly by the quasi-exospherichot electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00640510
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  • 6
    Electronic Resource
    Electronic Resource
    Planetary magnetospheres (1994)
    Springer
    Earth, moon and planets 67 (1994), S. 161-173 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Two decades ofin situ planetary exploration with fly-by missions have revealed a rich variety of magnetospheric configurations and dynamical phenomena, some anticipated and some remarkably surprising. These discoveries have set the stage for further exploration of planetary magnetospheres by orbiting spacecraft.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613300
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  • 7
    Electronic Resource
    Electronic Resource
    Coronal magnetic-field model with non-spherical source surface (1978)
    Springer
    Solar physics 60 (1978), S. 83-104 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Previous global models of coronal magnetic fields have used a geometrical construction based on a spherical source surface because of requirements for computational speed. As a result they have had difficulty accounting for (a) the tendency of full magnetohydrodynamic (MHD) models to predict non-radial plasma flow out to r ∼ 10r ⊙ and (b) the appreciable magnitude, ∼ 3γ, of B r , (the radial component of B) consistently observed at r ∼ 1 AU. We present a new modelling technique based on a non-spherical source surface, which is taken to be an isogauss of the underlying potential field generated by currents in or below the photosphere. This modification of the source surface significantly improves the agreement between the geometrical construction and the MHD solution while retaining most of the computational ease provided by a spherical source surface. A detailed comparison between the present source-surface model and the MHD solution is made for the internal dipole case. The resulting B field agrees well in magnitude and direction with the coronal B field derived from the full MHD equations. It shows evidence of the slightly equatorward meridional plasma flow that is characteristic of the MHD solution. Moreover, the B field obtained by using our non-spherical source surface agrees well with that observed by spacecraft in the vicinity of the Earth's orbit. Applied to a solar dipole field with a moment of 1 G-r ⊙ 3 , the present model predicts that B r at r ∼ 1 AU lies in the range of ∼ 1–2γ and is remarkably insensitive to heliomagnetic latitude. Our method should be applicable also to more general (i.e., more realistic) configurations of the solar magnetic field. Isogauss surfaces for two representative solar rotations, as calculated from expansions of observed photospheric magnetic-field data, are found to show large and significant deviations from sphericity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152334
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  • 8
    Electronic Resource
    Electronic Resource
    Analytical and Numerical Studies of the One-Dimensional Spin Facilitated Kinetic Ising Model (1999)
    Springer
    Journal of statistical physics 94 (1999), S. 173-201 
    Details
    ISSN: 1572-9613
    Keywords: lattice theory ; nonequilibrium kinetics ; glass transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The one-dimensional spin facilitated kinetic Ising model is studied analytically using the master equation and by simulations. The local state of the spins (corresponding to mobile and immobile cells) can change depending on the state of the neighbored spins, which reflects the high cooperativity inherent in glassy materials. The short-time behavior is analyzed using a Fock space representation for the master equation. The hierarchy of evolution equations for the averaged spin state and the time dependence of the spin autocorrelation function are calculated with different methods (mean-field theory, expansion in powers of the time, partial summation) and compared with numerical simulations. The long-time behavior can be obtained by mapping the one-dimensional spin facilitated kinetic Ising model onto a one-dimensional diffusion model containing birth and death processes. The resulting master equation is solved by van Kampen's size expansion, which leads to a Langevin equation with Gaussian noise. The predicted autocorrelation function and the global memory offer in the long-time limit a screened algebraic decay and a stretched exponential decay, respectively, consistent with numerical simulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004563329723
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  • 9
    Electronic Resource
    Electronic Resource
    Simulation of the magnetic structure of the inner heliosphere by means of a non-spherical source surface (1982)
    Springer
    Solar physics 77 (1982), S. 363-392 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this work we implement a new method for mapping the Sun's magnetic field B from the photosphere through the corona and interplanetary space. The method entails the derivation of B from a scalar potential within a ‘current-free’ annular volume bounded inside by the photosphere and outside by a prescribed non-spherical ‘source surface’ to which B is made (as nearly as possible) perpendicular. As usual we obtain the potential for the part of B that arises from currents inside the Sun by fitting an expansion to the observed line-of-sight component of B at the photosphere. The new aspect of our work is that we introduce a second least-squares fit to obtain the part of B that arises from currents outside the source surface. We do this by minimizing the mean-square tangential component of B over the source surface. This latter prescription allows a nearly arbitrary specification of the source surface, and no particular symmetry properties need be invoked for it. We have chosen as our prescription of the source surface one that reasonably simulates the expected physical consequences of coronal MHD effects. The magnetic field exterior to the source surface is made perpendicular to the source surface and is mapped throughout the heliosphere by means of a geometrical construction that appropriately generalizes the Parker spiral. Detailed comparisons have been made between this new model and observed coronal and interplanetary structures. The equatorward inclination of coronal helmet streamers is modeled much better with a non-spherical source surface than with a spherical one. There is clear evidence, however, that observational data underestimate the strength of photospheric polar magnetic fields. Neutral lines on the source surface (i.e., contours on which the normal component of B vanishes) generate heliospheric current sheets outside the source surface. In the particular case studied, two separate current sheets existed and were carried by the solar wind from the source surface to the boundary of the heliosphere. The result was a four-sector magnetic configuration near the ecliptic at 1 AU, and the observations were in good agreement with this prediction of the model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156118
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  • 10
    Electronic Resource
    Electronic Resource
    Geomagnetically trapped radiation (1975)
    Springer
    Space science reviews 17 (1975), S. 481-536 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This review covers the major developments in radiation-belt phenomenology of the past four years (1970–1973). This has been a period characterized by consolidation and refinement of ideas and measurements related to geomagnetically trapped particles. Significant progress has been made in understanding ion and electron pitch-angle distributions within the context of radial diffusion and pitch-angle diffusion, respectively. Comparison of alpha-particle and proton distributions has helped to clarify the relative strengths of known radial-diffusion mechanisms. Careful measurements have indicated the directional flux of cosmic-ray-albedo neutrons, which constitute (through beta decay) a major source of high-energy (≳ 20 MeV) inner-belt protons. Inclusion of radial-diffusion and geomagnetic-secular effects has brought the theory of the inner proton belt into reasonable agreement with observation. At very lowL values (L ≲ 1.2) atmospheric collisions have been found to facilitate the radial transport of 40 keV protons and 2 MeV electrons. The plasmapause has been identified as an important boundary for plasma instabilities (wave-particle interactions) that lead to particle precipitation and red-arc excitation. Suggestions have followed for artificially simulating such plasmaspheric effects by magnetospheric injection of cold barium or lithium plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00718583
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