68 research outputs found

### Nonlinear aspects of quantum plasma physics

Dense quantum plasmas are ubiquitous in planetary interiors and in compact
astrophysical objects, in semiconductors and micro-mechanical systems, as well
as in the next generation intense laser-solid density plasma interaction
experiments and in quantum x-ray free-electron lasers. In contrast to classical
plasmas, one encounters extremely high plasma number density and low
temperature in quantum plasmas. The latter are composed of electrons, positrons
and holes, which are degenerate. Positrons (holes) have the same (slightly
different) mass as electrons, but opposite charge. The degenerate charged
particles (electrons, positrons, holes) follow the Fermi-Dirac statistics. In
quantum plasmas, there are new forces associated with i) quantum statistical
electron and positron pressures, ii) electron and positron tunneling through
the Bohm potential, and iii) electron and positron angular momentum spin.
Inclusion of these quantum forces provides possibility of very high-frequency
dispersive electrostatic and electromagnetic waves (e.g. in the hard x-ray and
gamma rays regimes) having extremely short wavelengths. In this review paper,
we present theoretical backgrounds for some important nonlinear aspects of
wave-wave and wave-electron interactions in dense quantum plasmas.
Specifically, we shall focus on nonlinear electrostatic electron and ion plasma
waves, novel aspects of 3D quantum electron fluid turbulence, as well as
nonlinearly coupled intense electromagnetic waves and localized plasma wave
structures. Also discussed are the phase space kinetic structures and
mechanisms that can generate quasi-stationary magnetic fields in dense quantum
plasmas. The influence of the external magnetic field and the electron angular
momentum spin on the electromagnetic wave dynamics is discussed.Comment: 42 pages, 20 figures, accepted for publication in Physics-Uspekh

### A new electromagnetic wave in a pair plasma

A new nonlinear electromagnetic wave mode in a plasma is reported. Its
existence depends on the interaction of an intense circularly polarized
electromagnetic wave with a plasma, where quantum electrodynamical
photon--photon scattering is taken into account. As an illustration, we
consider a pair plasma and show that the new mode can be significant in
astrophysical settings and in the next generation laser-plasma systems.Comment: 3 page

### Laser acceleration of monoenergetic protons via a double layer emerging from an ultra-thin foil

We present theoretical and numerical studies of the acceleration of monoenergetic protons in a double layer formed by the laser irradiation of an ultra-thin film. The ponderomotive force of the laser light pushes the electrons forward, and the induced space charge electric field pulls the ions and makes the thin foil accelerate as a whole. The ions trapped by the combined electric field and inertial force in the accelerated frame, together with the electrons trapped in the well of the ponderomotive and ion electric field, form a stable double layer. The trapped ions are accelerated to monoenergetic energies up to 100 MeV and beyond, making them suitable for cancer treatment. We present an analytic theory for the laser-accelerated ion energy and for the amount of trapped ions as functions of the laser intensity, foil thickness and the plasma number density. We also discuss the underlying physics of the trapped and untrapped ions in a double layer. The analytical results are compared with those obtained from direct Vlasov simulations of the fully nonlinear electron and ion dynamics that is controlled by the laser light

### Wave Propagation and Diffusive Transition of Oscillations in Pair Plasmas with Dust Impurities

In view of applications to electron-positron pair-plasmas and fullerene
pair-ion-plasmas containing charged dust impurities a thorough discussion is
given of three-component Plasmas. Space-time responses of multi-component
linearized Vlasov plasmas on the basis of multiple integral equations are
invoked. An initial-value problem for Vlasov-Poisson -Ampere equations is
reduced to the one multiple integral equation and the solution is expressed in
terms of forcing function and its space-time convolution with the resolvent
kernel. The forcing function is responsible for the initial disturbance and the
resolvent is responsible for the equilibrium velocity distributions of plasma
species. By use of resolvent equations, time-reversibility, space-reflexivity
and the other symmetries are revealed. The symmetries carry on physical
properties of Vlasov pair plasmas, e.g., conservation laws. Properly choosing
equilibrium distributions for dusty pair plasmas, we can reduce the resolvent
equation to: (i) the undamped dispersive wave equations, (ii) wave-diffusive
transport equation (iii) and diffusive transport equations of oscillations. In
the last case we have to do with anomalous diffusion employing fractional
derivatives in time and space. Fractional diffusion equations account for
typical anomalous features, which are observed in many systems, e.g. in the
case of dispersive transport in amorphous semiconductors, liquid crystals,
polymers, proteins and biosystems.Comment: 6 page

### 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

### Nonlinear Propagation of Crossing Electromagnetic Waves in Vacuum due to Photon-Photon Scattering

We review the theory for photon-photon scattering in vacuum, and some of the
proposals for its experimental search, including the results of our recent
works on the subject. We then describe a very simple and sensitive proposal of
an experiment and discuss how it can be used at the present (HERCULES) and the
future (ELI) ultrahigh power laser facilities either to find the first evidence
of photon-photon scattering in vacuum, or to significantly improve the current
experimental limits.Comment: Talk delivered (by D.T.) at the International Workshop on the
Frontiers of Modern Plasma Physics, Trieste, 2008. To appear in the
proceeding

### Statistical description of short pulses in long optical fibers: Effects of nonlocality

We present a statistical description of the propagation of short pulses in
long optical fibers, taking into account the Kerr and nonlocal nonlinearities
on an equal footing. We use the Wigner approach on the modified nonlinear
Schroedinger equation to obtain a wave kinetic equation and a nonlinear
dispersion relation. The latter exhibit that the optical pulse decoherence
reduces the growth rate of the modulational instability, and thereby contribute
to the nonlinear stability of the pulses in long optical fibers. It is also
found that the interaction between spectral broadening and nonlocality tends to
extend the instability region.Comment: 9 pages, 1 figur

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