992 research outputs found
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
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
Instability and dynamics of two nonlinearly coupled laser beams in a plasma
We investigate the nonlinear interaction between two laser beams in a plasma
in the weakly nonlinear and relativistic regime. The evolution of the laser
beams is governed by two nonlinear Schroedinger equations that are coupled with
the slow plasma density response. We study the growth rates of the Raman
forward and backward scattering instabilities as well of the Brillouin and
self-focusing/modulational instabilities. The nonlinear evolution of the
instabilities is investigated by means of direct simulations of the
time-dependent system of nonlinear equations.Comment: 18 pages, 8 figure
Ultrarelativistic nanoplasmonics as a new route towards extreme intensity attosecond pulses
The generation of ultra-strong attosecond pulses through laser-plasma
interactions offers the opportunity to surpass the intensity of any known
laboratory radiation source, giving rise to new experimental possibilities,
such as quantum electrodynamical tests and matter probing at extremely short
scales. Here we demonstrate that a laser irradiated plasma surface can act as
an efficient converter from the femto- to the attosecond range, giving a
dramatic rise in pulse intensity. Although seemingly similar schemes have been
presented in the literature, the present setup deviates significantly from
previous attempts. We present a new model describing the nonlinear process of
relativistic laser-plasma interaction. This model, which is applicable to a
multitude of phenomena, is shown to be in excellent agreement with
particle-in-cell simulations. We provide, through our model, the necessary
details for an experiment to be performed. The possibility to reach intensities
above 10^26 W/cm^2, using upcoming 10 petawatt laser sources, is demonstrated.Comment: 15 pages, 5 figure
Modulational instability criteria for two-component Bose-Einstein condensates
The stability of colliding Bose-Einstein condensates is investigated. A set
of coupled Gross-Pitaevskii equations is thus considered, and analyzed via a
perturbative approach. No assumption is made on the signs (or magnitudes) of
the relevant parameters like the scattering lengths and the coupling
coefficients. The formalism is therefore valid for asymmetric as well as
symmetric coupled condensate wave states. A new set of explicit criteria is
derived and analyzed. An extended instability region, in addition to an
enhanced instability growth rate is predicted for unstable two component
bosons, as compared to the individual (uncoupled) state.Comment: 4 pages, 1 figur
The intensity dependent mass shift: existence, universality and detection
The electron mass shift in a laser field has long remained an elusive
concept. We show that the mass shift can exist in pulses but that it is neither
unique nor universal: it can be reduced by pulse shaping. We show also that the
detection of mass shift effects in laser-particle scattering experiments is
feasible with current technology, even allowing for the transverse structure of
realistic beams.Comment: 5 pages, 4 figures. V2: references added, introduction expande
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