936 research outputs found
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
Nonlinear Interactions Between Gravitational Radiation and Modified Alfven Modes in Astrophysical Dusty Plasmas
We present an investigation of nonlinear interactions between Gravitational
Radiation and modified Alfv\'{e}n modes in astrophysical dusty plasmas.
Assuming that stationary charged dust grains form neutralizing background in an
electron-ion-dust plasma, we obtain the three wave coupling coefficients, and
calculate the growth rates for parametrically coupled gravitational radiation
and modified Alfv\'{e}n-Rao modes. The threshold value of the gravitational
wave amplitude associated with convective stabilization is particularly small
if the gravitational frequency is close to twice the modified Alfv\'en
wave-frequency. The implication of our results to astrophysical dusty plasmas
is discussed.Comment: A few typos corrected. Published in Phys. Rev.
New Quantum Limits in Plasmonic Devices
Surface plasmon polaritons (SPPs) have recently been recognized as an
important future technique for microelectronics. Such SPPs have been studied
using classical theory. However, current state-of-the-art experiments are
rapidly approaching nanoscales, and quantum effects can then become important.
Here we study the properties of quantum SPPs at the interface between an
electron quantum plasma and a dielectric material. It is shown that the effect
of quantum broadening of the transition layer is most important. In particular,
the damping of SPPs does not vanish even in the absence of collisional
dissipation, thus posing a fundamental size limit for plasmonic devices.
Consequences and applications of our results are pointed out.Comment: 5 pages, 2 figures, to appear in Europhysics Letter
Resonant interaction between gravitational waves, electromagnetic waves and plasma flows
In magnetized plasmas gravitational and electromagnetic waves may interact
coherently and exchange energy between themselves and with plasma flows. We
derive the wave interaction equations for these processes in the case of waves
propagating perpendicular or parallel to the plasma background magnetic field.
In the latter case, the electromagnetic waves are taken to be circularly
polarized waves of arbitrary amplitude. We allow for a background drift flow of
the plasma components which increases the number of possible evolution
scenarios. The interaction equations are solved analytically and the
characteristic time scales for conversion between gravitational and
electromagnetic waves are found. In particular, it is shown that in the
presence of a drift flow there are explosive instabilities resulting in the
generation of gravitational and electromagnetic waves. Conversely, we show that
energetic waves can interact to accelerate particles and thereby \emph{produce}
a drift flow. The relevance of these results for astrophysical and cosmological
plasmas is discussed.Comment: 12 pages, 1 figure, typos corrected and numerical example adde
Parametric excitation of plasma waves by gravitational radiation
We consider the parametric excitation of a Langmuir wave and an
electromagnetic wave by gravitational radiation, in a thin plasma on a
Minkowski background. We calculate the coupling coefficients starting from a
kinetic description, and the growth rate of the instability is found. The
Manley-Rowe relations are fulfilled only in the limit of a cold plasma. As a
consequence, it is generally difficult to view the process quantum
mechanically, i.e. as the decay of a graviton into a photon and a plasmon.
Finally we discuss the relevance of our investigation to realistic physical
situations.Comment: 5 pages, REVTe
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
From extended phase space dynamics to fluid theory
We derive a fluid theory for spin-1/2 particles starting from an extended
kinetic model based on a spin-projected density matrix formalism. The evolution
equation for the spin density is found to contain a pressure-like term. We give
an example where this term is important by looking at a linear mode previously
found in a spin kinetic model.Comment: 4 page
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
Spin and magnetization effects in plasmas
We give a short review of a number of different models for treating
magnetization effects in plasmas. In particular, the transition between kinetic
models and fluid models is discussed. We also give examples of applications of
such theories. Some future aspects are discussed.Comment: 18 pages, 1 figure. To appear in Plasma Physics and Controlled
Fusion, Special Issue for the 37th ICPP, Santiago, Chil
Parametric phenomena of the particle dynamics in a periodic gravitational wave field
We establish exactly solvable models for the motion of neutral particles,
electrically charged point and spin particles (U(1) symmetry), isospin
particles (SU(2) symmetry), and particles with color charges (SU(3) symmetry)
in a gravitational wave background. Special attention is devoted to parametric
effects induced by the gravitational field. In particular, we discuss
parametric instabilities of the particle motion and parametric oscillations of
the vectors of spin, isospin, and color charge.Comment: 26 pages, to be published in J. Math. Phy
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