708 research outputs found
Short wavelength quantum electrodynamical correction to cold plasma-wave propagation
The effect of short wavelength quantum electrodynamic (QED) correction on
plasma-wave propagation is investigated. The effect on plasma oscillations and
on electromagnetic waves in an unmagnetized as well as a magnetized plasma is
investigated. The effects of the short wavelength QED corrections are most
significant for plasma oscillations and for extraordinary modes. In particular,
the QED correction allow plasma oscillations to propagate, and the
extra-ordinary mode looses its stop band. The significance of our results is
discussed.Comment: 12 pages, 5 figure
Spin solitons in magnetized pair plasmas
A set of fluid equations, taking into account the spin properties of the
electrons and positrons in a magnetoplasma, are derived. The
magnetohydrodynamic limit of the pair plasma is investigated. It is shown that
the microscopic spin properties of the electrons and positrons can lead to
interesting macroscopic and collective effects in strongly magnetized plasmas.
In particular, it is found that new Alfvenic solitary structures, governed by a
modified Korteweg-de Vries equation, are allowed in such plasmas. These
solitary structures vanish if the quantum spin effects are neglected. Our
results should be of relevance for astrophysical plasmas, e.g. in pulsar
magnetospheres.Comment: 7 page
Localized whistlers in magnetized spin quantum plasmas
The nonlinear propagation of electromagnetic (EM) electron-cyclotron waves
(whistlers) along an external magnetic field, and their modulation by
electrostatic small but finite amplitude ion-acoustic density perturbations are
investigated in a uniform quantum plasma with intrinsic spin of electrons. The
effects of the quantum force associated with the Bohm potential and the
combined effects of the classical as well as the spin-induced ponderomotive
forces (CPF and SPF respectively) are taken into consideration. The latter
modify the local plasma density in a self-consistent manner. The coupled modes
of wave propagation is shown to be governed by a modified set of nonlinear
Schr\"{o}dinger-Boussinesq-like equations which admit exact solutions in form
of stationary localized envelopes. Numerical simulation reveals the existence
of large-scale density fluctuations that are self-consistently created by the
localized whistlers in a strongly magnetized high density plasma. The
conditions for the modulational instability (MI) and the value of its growth
rate are obtained. Possible applications of our results, e.g., in strongly
magnetized dense plasmas and in the next generation laser-solid density plasma
interaction experiments are discussed.Comment: 9 pages, 4 figures; To appear in Physical Review E (2010
Ultrafast Electron Holes in Plasma Phase Space Dynamics
Electron holes (EH) are localized modes in plasma kinetic theory which appear
as vortices in phase space. Earlier research on EH is based on the Schamel
distribution function (df). A novel distribution function is proposed here,
generalizing the original Schamel df in a recursive manner. Nonlinear solutions
obtained by kinetic simulations are presented, with velocities twice the
electron thermal speed. Using 1D-1V kinetic simulations, their propagation
characteristics are traced and their stability is established by studying their
long-time evolution and their behavior through mutual collisions.Comment: 5 pages, 6 figures, accepted in Scientific Report
Ferroplasmas: Magnetic Dust Dynamics in a Conducting Fluid
We consider a dusty plasma, in which the dust particles have a magnetic
dipole moment. A Hall-MHD type of model, generalized to account for the
intrinsic magnetization, is derived. The model is shown to be energy
conserving, and the energy density and flux is derived. The general dispersion
relation is then derived, and we show that kinetic Alfv\'en waves exhibit an
instability for a low temperature and high density plasma. We discuss the
implication of our results.Comment: 6 pages, 1 figur
On the possibility of metamaterial properties in spin plasmas
The fluid theory of plasmas is extended to include the properties of electron
spin. The linear theory of waves in a magnetized plasma is presented, and it is
shown that the spin effects causes a change of the magnetic permeability.
Furthemore, by changing the direction of the external magnetic field, the
magnetic permability may become negative. This leads to instabilities in the
long wavelength regimes. If these can be controlled, however, the spin plasma
becomes a metamaterial for a broad range of frequencies, i.e. above the ion
cyclotron frequency but below the electron cyclotron frequency. The
consequences of our results are discussed.Comment: 10 page
Quantum Electrodynamical Photon Splitting in Magnetized Nonlinear Pair Plasmas
We present for the first time the nonlinear dynamics of quantum
electrodynamic (QED) photon splitting in a strongly magnetized
electron-positron (pair) plasma. By using a QED corrected Maxwell equation, we
derive a set of equations that exhibit nonlinear couplings between
electromagnetic (EM) waves due to nonlinear plasma currents and QED
polarization and magnetization effects. Numerical analyses of our coupled
nonlinear EM wave equations reveal the possibility of a more efficient decay
channel, as well as new features of energy exchange among the three EM modes
that are nonlinearly interacting in magnetized pair plasmas. Possible
applications of our investigation to astrophysical settings, such as magnetars,
are pointed out.Comment: 5 pages, 3 figures, to appear in Physical Review Letter
Modified Jeans Instability Criteria for Magnetized Systems
The Jeans instability is analyzed for dense magnetohydrodynamic plasmas with
intrinsic magnetization, the latter due to collective electron spin effects.
Furthermore, effects of electron tunneling as well as the Fermi pressure are
included. It is found that the intrinsic magnetization of the plasma will
enhance the Jeans instability, and can significantly modify the structure of
the instability spectra. Implications and limitations of our results are
discussed, as well as possible generalizations.Comment: 7 pages, 6 figures, submitted to Physics of Plasma
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