1,711 research outputs found
Modulational instability of partially coherent signals in electrical transmission lines
We present an investigation of the modulational instability of partially
coherent signals in electrical transmission lines. Starting from the modified
Ginzburg-Landau equations and the Wigner-Moyal representation, we derive a
nonlinear dispersion relation for the modulational instability. It is found
that the effect of signal broadbandness reduces the growth rate of the
modulational instability.Comment: 5 pages, 1 figure, to appear in Physical Review
Circularly polarized waves in a plasma with vacuum polarization effects
The theory for large amplitude circularly polarized waves propagating along
an external magnetic field is extended in order to include also vacuum
polarization effects. A general dispersion relation, which unites previous
results, is derived.Comment: 5 pages (To appear in Physics of Plasmas
Wakefield generation in magnetized plasmas
We consider wakefield generation in plasmas by electromagnetic pulses
propagating perpendicular to a strong magnetic field, in the regime where the
electron cyclotron frequency is equal to or larger than the plasma frequency.
PIC-simulations reveal that for moderate magnetic field strengths previous
results are re-produced, and the wakefield wavenumber spectrum has a clear peak
at the inverse skin depth. However, when the cyclotron frequency is
significantly larger than the plasma frequency, the wakefield spectrum becomes
broad-band, and simultaneously the loss rate of the driving pulse is much
enhanced. A set of equations for the scalar and vector potentials reproducing
these results are derived, using only the assumption of a weakly nonlinear
interaction.Comment: 6 pages, 8 figure
Magnetosonic solitons in a dusty plasma slab
The existence of magnetosonic solitons in dusty plasmas is investigated. The
nonlinear magnetohydrodynamic equations for a warm dusty magnetoplasma are thus
derived. A solution of the nonlinear equations is presented. It is shown that,
due to the presence of dust, static structures are allowed. This is in sharp
contrast to the formation of the so called shocklets in usual magnetoplasmas. A
comparatively small number of dust particles can thus drastically alter the
behavior of the nonlinear structures in magnetized plasmas.Comment: 7 pages, 6 figure
Effects of the -factor in semi-classical kinetic plasma theory
A kinetic theory for spin plasmas is put forward, generalizing those of
previous authors. In the model, the ordinary phase space is extended to include
the spin degrees of freedom. Together with Maxwell's equations, the system is
shown to be energy conserving. Analysing the linear properties, it is found
that new types of wave-particle resonances are possible, that depend directly
on the anomalous magnetic moment of the electron. As a result new wave modes,
not present in the absence of spin, appear. The implications of our results are
discussed.Comment: 4 pages, two figures, version to appear in Physical Review Letter
Spin contribution to the ponderomotive force in a plasma
The concept of a ponderomotive force due to the intrinsic spin of electrons
is developed. An expression containing both the classical as well as the
spin-induced ponderomotive force is derived. The results are used to
demonstrate that an electromagnetic pulse can induce a spin-polarized plasma.
Furthermore, it is shown that for certain parameters, the nonlinear
back-reaction on the electromagnetic pulse from the spin magnetization current
can be larger than that from the classical free current. Suitable parameter
values for a direct test of this effect are presented.Comment: 4 pages, 2 figures, version accepted for publication in Physical
Review Letter
Kinetic theory of electromagnetic ion waves in relativistic plasmas
A kinetic theory for electromagnetic ion waves in a cold relativistic plasma
is derived. The kinetic equation for the broadband electromagnetic ion waves is
coupled to the slow density response via an acoustic equation driven by
ponderomotive force like term linear in the electromagnetic field amplitude.
The modulational instability growth rate is derived for an arbitrary spectrum
of waves. The monochromatic and random phase cases are studied.Comment: 7 pages, 4 figures, to appear in Physics of Plasma
Fluid moment hierarchy equations derived from gauge invariant quantum kinetic theory
The gauge invariant electromagnetic Wigner equation is taken as the basis for
a fluid-like system describing quantum plasmas, derived from the moments of the
gauge invariant Wigner function. The use of the standard, gauge dependent
Wigner function is shown to produce inconsistencies, if a direct correspondence
principle is applied. The propagation of linear transverse waves is considered
and shown to be in agreement with the kinetic theory in the long wavelength
approximation, provided an adequate closure is chosen for the macroscopic
equations. A general recipe to solve the closure problem is suggested.Comment: 12 pages, 1 figur
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