Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Macroscopic structures of inhomogeneous, Navier–Stokes turbulence (1999)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 11 (1999), S. 2367-2380 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Macroscopic properties of inhomogeneous, Navier–Stokes turbulence are calculated using a fundamental theoretical approach. Starting from a set of solenoidal basis vectors suitable for describing a turbulence bounded by infinite, parallel free-slip planes, invoking a random-phase approximation, and using the eddy-damped quasinormal Markovian closure, various quantities of dynamical interest are calculated. Quantities that affect the evolution of both the momentum density and the kinetic energy density of the turbulently evolving fluid are studied. These quantities include the ensemble-averaged values of gradients of the triple-velocity correlation and the pressure–velocity correlation. When the energy spectrum in wave-number space lacks certain reflection symmetries, a nontrivial mean flow velocity will be seen to emerge out of the turbulent eddies. In turn, these mean flow velocities will affect the evolution of the turbulence. Of course, such physically interesting mean-field structures cannot arise in dynamics suffused by the assumption of statistical homogeneity. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870098
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Streaming instabilities of a non-neutral plasma with turning points (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 1378-1392 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Streaming instabilities of a reflexing beam in a slab model of a beam Penning trap or an inertial electrostatic confinement device are studied. Particles may have turning points that may be between the walls. Linear theory is developed for the case in which the self-field cancels the external potential. If the electric field perturbation is odd about the center, these two-stream modes couple the slow waves on the two beams. Even modes consist of two classes: a class of two-stream modes and another class of complex-frequency modes, coupling the slow and fast waves on the same beam. The latter are unstable over a larger range than the two-stream modes. Thermal spread is stabilizing only when the thermal and streaming velocities are comparable. Numerical results for the general class of equilibria show both two-stream-like modes and oscillating modes. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871354
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Hamiltonian representation for helically symmetric magnetic fields (1985)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 26 (1985), S. 991-993 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: It is proved that one of the two potentials used in a standard representation of helically symmetric magnetic fields is a Hamiltonian that generates the magnetic lines of force. It is proved also that if the other potential is restricted to be proportional to this Hamiltonian, then the radial components of current density and magnetic field are proportional. This restriction applies, for example, to constant-λ, helically symmetric, force-free magnetic fields [j(r)=λB(r)] relevant to both fusion physics and astrophysics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.526506
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Collective effects on equilibria of trapped charged plasmas (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 3196-3203 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A fluid model is used to study analytically the equilibria of charged plasma in traps. Several geometries are explored: a one-dimensional slab equilibrium of a finite-temperature plasma mechanically confined by two plates that are externally maintained at fixed potentials, and both spherical as well as spheroidal equilibria of a zero-temperature plasma confined in traps distorted from the standard Penning-trap configuration by virtue of the multipole moments of the trapped plasma. Although this study was motivated by the necessity of understanding possible collective effects in charged-plasma traps for the design and future diagnosis of the ambitious antiproton-gravity experiment being undertaken by the Los Alamos Collaboration [Proceedings of the Second Conference on the Intersections between Particle and Nuclear Physics (American Institute of Physics, New York, 1986), AIP Pub. No. 150, p. 436], this study is also relevant to current and future attempts at producing strongly coupled plasmas and ionic crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866495
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Non-neutral plasma compression to ultrahigh density (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 3890-3901 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Oscillations of a cold, homogeneous, non-neutral plasma spheroid are considered. A new class of purely compressional, large-amplitude, nonlinear oscillations is found. With a periodically time-varying external electrostatic quadrupole and a static magnetic field, such oscillations periodically can produce arbitrarily large plasma densities with only a modest swing in the applied quadrupole. In limiting cases, one- to three-dimensional plasma oscillations are true normal modes, requiring no variation of the applied quadrupole. For appropriate parameters, peak density is associated with a very "soft core,'' so that an extremely high density is associated with a very modest size at minimum density. Further, cold-plasma stability is examined for these cases. For three-dimensional oscillations, all modes are stable. For two-dimensional oscillations, modes with intermediate axial wavelengths are not examined in detail. Long-axial-wavelength modes are found to be unstable only for small oscillation amplitudes. These modes are stable at sufficiently large oscillation amplitude. Those modes with a very short axial wavelength are always stable. Thus, it is very likely that extremely high densities may be produced in a compact system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860346
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Magnetic topology of helical Ohmic steady states (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 787-796 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Necessary analytic constraints for a force-free, single harmonic, single helicity, magnetic-field configuration to be an Ohmic equilibrium are derived. These conditions imply that the typical configuration possesses an m=1 helical structure and has only open magnetic flux surfaces. The conclusion is drawn that Taylor's helical state is not a steady state in the presence of resistive dissipation, no matter how small. Nevertheless, the field configurations that commonly have been associated with Taylor's minimum energy states retain significance because they may represent either the mean configuration of a temporally fluctuating state or the zero-resistivity limit of a (hypothetical) three-dimensional, Ohmic equilibrium. Examples of single harmonic, single helicity, reversed-field, Ohmic equilibria are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866329
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Driven, resistive, force-free plasmas and reversed-field-pinch physics revisited (1985)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 28 (1985), S. 1155-1159 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Solutions of the coupled steady-state equations, Ohm's law, and curl B=λ(r)B, are obtained in slab and cylindrical geometries with two ignorable coordinates. Aside from the stark feature of small toroidal-field reversal near the plasma edge, the numerically obtained field profiles in cylindrical geometry mimic the observed experimental reversed-field-pinch profiles; e.g., Bz is a monotonically decreasing function of radius and, if the parallel resistivity is spatially independent, then also λ (i.e., j/B) is a monotonically decreasing function of radius. It is also shown that toroidal-field reversal is impossible in a toroidally symmetric, force-free, steady-state, Ohmic plasma having nested flux surfaces. It is suggested that the more sophisticated dynamics required to sustain the observed field reversal may be able to be relegated to the outer annular region containing the reversal surface. Understanding of this dynamics then may be facilitated by the fact that only one field component, the poloidal one, is dominant throughout this region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865039
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Production and application of dense Penning trap plasmas (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 3651-3660 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new paradigm for producing well-confined, dense-thermonuclear plasmas is described. The convergence of a radial beam distribution of a Penning-trap-confined plasma produces a dense inertially confined non-neutral plasma. The equilibrium, stability, classical transport, and particle-handling properties of such a concept are developed. The application of this approach to controlled fusion using a pure electron plasma to form a central virtual cathode in which ions are electrostatically confined is discussed. On one hand, extreme plasma control is required, placing the major uncertainty on issues of machine precision. On the other hand, development is characterized by the manufacture and testing of extremely small and inexpensive systems. Thus, it would seem that a timely experimental test of this concept would be ineluctable. Success at such experiments might indicate an alternate path to practical fusion applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860837
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Brillouin limit for non-neutral plasma in inhomogeneous magnetic fields (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1355-1363 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of magnetic field inhomogeneity upon the maximum density of non-neutral plasma that can be confined in hydrostatic equilibrium under the combined influence of electrostatic and magnetostatic fields is explored in two cases of azimuthally symmetric geometries: first, a plasma in an arbitrary vacuum poloidal magnetic field, B=Br(r,z)rˆ+Bz(r,z)zˆ, and second, a toroidal plasma in a toroidal vacuum magnetic field. For the poloidal field case, it is demonstrated that the Brillouin limit on number density can be achieved only with a homogeneous axial magnetic field. For the toroidal field case, it is demonstrated that although the Brillouin limit does not provide a limitation on the local number density confined, it nevertheless does provide an upper limit on the total amount of non-neutral plasma confined in equilibrium. It is also demonstrated that when viscosity is present in the toroidal field case, its effect to first order in the inverse aspect ratio can be opposed by a readjustment of only the external electrostatic potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859700
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Compressional oscillation frequency of an anharmonic oscillator: The spherical non-neutral plasma (1994)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 35 (1994), S. 2349-2356 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The physics of ultrahigh density compressional oscillations of a non-neutral plasma has already been discussed. Here, one technical facet will be analytically plumbed; namely the frequency of such oscillations. These oscillations are governed by differential equations whose solutions involve elliptic integrals of the third kind. Nevertheless, without studying the properties of these integrals, a procedure is demonstrated which permits the development of an analytic formula for the frequency of these anharmonic oscillations. This frequency is shown to be proportional to the cyclotron frequency ωc with a constant of proportionality that depends on the ratio of the difference between the radii of the outer and inner turning points divided by the sum of the radii of the two turning points. These radii, in turn, depend on two constants of integration that represent the energy of the compressional oscillations and the amount of charge in the plasma cloud. The final result of the analysis is that the frequency varies only from ωc/(square root of)2 when the above ratio is small to (2/3)1/2ωc when the ratio is large. These limits are also obtained intuitively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.530557
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...