669 research outputs found
A note on the Weibel instability and thermal fluctuations
The thermal fluctuation level of the Weibel instability is recalculated. It
is shown that the divergence of the fluctuations at long wavelengths, i.e. the
Weibel infrared catastrophe, never occurs. At large wavelengths the thermal
fluctuation level is terminated by the presence of even the smallest available
stable thermal anisotropy. Weibel fields penetrate only one skin depth into the
plasma. When excited inside, they cause layers of antiparallel fields of skin
depth width and vortices which may be subject to reconnection.Comment: 4 pages, 2 figures, accepted by Ann Geophy
Collisionless reconnection: Mechanism of self-ignition in thin current sheets
The spontaneous onset of magnetic reconnection in thin collisionless current
sheets is shown to result from a thermal-anisotropy driven magnetic
Weibel-mode, generating seed-magnetic field {\sf X}-points in the centre of the
current layer.Comment: 8 pages, 6 figures, prepared for Annales Geophysica
Ultrarelativistic generalized Lorentzian thermodynamics and the differential cosmic ray energy flux
We apply the ultrarelativistic generalized Lorentzian quasi-equilibrium
thermodynamic energy distribution to the energy spectrum of galactic cosmic ray
fluxes. The inferred power law slopes contain a component which evolves with
cosmic ray energy in steps of thirds, resembling the sequence of structure
functions in fully developed Kolmogorov turbulence. Within the generalized
thermodynamics the chemical potential can be estimated from the deviation of
the fluxes at decreasing energy. Both may throw some light on the cosmic ray
acceleration mechanism to very high energies.Comment: 7 pages, 2 figures, prepared for a Meeting on Cosmic Rays and Power
Law Tail
Kinetic theory of information -- the dynamics of information
A kinetic approach to the notion of information is proposed, based on
Liouville kinetic theory. The general kinetic equation for the evolution of the
N-particle information in a Hamiltonian system of large
particle number is obtained. It is shown that the -particle
information is strictly conserved. Defining reduced particle number information
densities in phase space should be possible to obtain a kinetic equation for
the ordinary one-particle information
following the Bogoliubov prescription. The kinetic equation for
is a kind of generalized Boltzmann equation with interaction term depending on
the hierarchy of reduced informations. This term in its general form is the
most general expression for the Kolmogorov entropy rate of evolution of the
information.Comment: 5 pages, no figures, accepted in Front. Phy
Incomplete-exclusion Statistical Mechanics in Non-collisional Violent Relaxation of Celestial Objects
Violent relaxation has been proposed half a century ago to bear
responsibility for non-collisional dynamics and formation of gravitationally
bound systems of extended celestial objects (agglomeration of stars, galaxies,
clusters of galaxies) when reaching an approximate equilibrium state which can
be described thermodynamically. The Lynden-Bell equilibrium distribution of
such systems, resulting from a spatial exclusion principle, had been shown to
be an analog to the Fermi distribution of states in solid state physics. Real
extended objects like galaxies do not completely exclude each other, however.
Permitting for partial exclusion leads to a modification of the equilibrium
distribution. Here we show that this case can be treated in analogy to a
hypothetical incomplete population of Fermi states. An incomplete-exclusion
equilibrium distribution is obtained which enters the violent relaxation
theory.Comment: 17 pages, no figure
The mirror mode: A "superconducting'' space plasma analogue
We examine the physics of the magnetic mirror mode in its final state of
saturation, the thermodynamic equilibrium, to demonstrate that the mirror mode
is the analogue of a superconducting effect in a classical anisotropic-pressure
space plasma. Two different spatial scales are identified which control the
behaviour of its evolution. These are the ion inertial scale
based on the excess density generated in the
mirror mode, and a correlation length. This can be either the Debye length, the
ion gyro-radius, or a turbulent correlation length. The mirror mode equilibrium
structure under saturation is determined by the Landau-Ginzburg ratio of these
two length scales. Mirror modes then behave like type II superconductors,
naturally giving rise to chains of local depletions of the magnetic field of
the kind observed in the mirror mode, providing the plasma a short scale
magnetic bubble texture. This might be important in the study of magnetic
turbulence in plasmas.Comment: 13 pages, 2 figure, Discussion paper, to appear in Ann. Geophy
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