24,276 research outputs found
Neutrino magnetohydrodynamics
A new neutrino magnetohydrodynamics (NMHD) model is formulated, where the
effects of the charged weak current on the electron-ion magnetohydrodynamic
fluid are taken into account. The model incorporates in a systematic way the
role of the Fermi neutrino weak force in magnetized plasmas. A fast
neutrino-driven short wavelengths instability associated with the magnetosonic
wave is derived. Such an instability should play a central role in strongly
magnetized plasma as occurs in supernovae, where dense neutrino beams also
exist. In addition, in the case of nonlinear or high frequency waves, the
neutrino coupling is shown to be responsible for breaking the frozen-in
magnetic field lines condition even in infinite conductivity plasmas.
Simplified and ideal NMHD assumptions were adopted and analyzed in detail
Anomalous Magnetohydrodynamics
Anomalous symmetries induce currents which can be parallel rather than
orthogonal to the hypermagnetic field. Building on the analogy with charged
liquids at high magnetic Reynolds numbers, the persistence of anomalous
currents is scrutinized for parametrically large conductivities when the plasma
approximation is accurate. Different examples in globally neutral systems
suggest that the magnetic configurations minimizing the energy density with the
constraint that the helicity be conserved coincide, in the perfectly conducting
limit, with the ones obtainable in ideal magnetohydrodynamics where the
anomalous currents are neglected. It is argued that this is the rationale for
the ability of extending to anomalous magnetohydrodynamics the hydromagnetic
solutions characterized by finite gyrotropy. The generally covariant aspects of
the problem are addressed with particular attention to conformally flat
geometries which are potentially relevant for the description of the
electroweak plasma prior to the phase transition.Comment: 25 pages, no figure
Lagrangian analysis of alignment dynamics for isentropic compressible magnetohydrodynamics
After a review of the isentropic compressible magnetohydrodynamics (ICMHD)
equations, a quaternionic framework for studying the alignment dynamics of a
general fluid flow is explained and applied to the ICMHD equations.Comment: 12 pages, 2 figures, submitted to a Focus Issue of New Journal of
Physics on "Magnetohydrodynamics and the Dynamo Problem" J-F Pinton, A
Pouquet, E Dormy and S Cowley, editor
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