124 research outputs found
Fundamental Physics and Relativistic Laboratory Astrophysics with Extreme Power Lasers
The prospects of using extreme relativistic laser-matter interactions for
laboratory astrophysics are discussed. Laser-driven process simulation of
matter dynamics at ultra-high energy density is proposed for the studies of
astrophysical compact objects and the early universe.Comment: 12 pages, 15 figures. Invited talk at European Conference on
Laboratory Astrophysics (ECLA), 26-30 September, 2011, Paris, France.
Submitted to European Astronomical Society Publications Serie
Bow wave from ultra-intense electromagnetic pulses in plasmas
We show a new effect of the bow wave excitation by an intense short laser
pulse propagating in underdense plasma. Due to spreading of the laser pulse
energy in transverse direction, the bow wave causes a large-scale transverse
modulation of the electron density. This can significantly increase the
electric potential of the wake wave since the wake wave is generated in the
region much wider than the laser pulse waist.Comment: 6 pages, 4 figure
Relativistic Whistle: High Order Harmonics Induced by the Ultra-Intense Laser Pulse Propagating inside the Fiber
A propagation of an ultra-intense short laser pulse in a fiber is
investigated with two dimensional Particle-in-Cell simulations. The fiber is a
narrow hollow channel with walls consisting of overdense plasma. In the
nonlinear interaction of the laser pulse with fiber walls high order harmonics
are generated. Sufficiently high harmonics, for which the fiber walls are
transparent, propagate outwards at certain angle. This is a scheme of a
generator of ultra-short pulses of coherent light with a very short wavelength.Comment: 6 pages, 6 figure
On annihilation of the relativistic electron vortex pair in collisionless plasmas
In contrast to hydrodynamic vortices, vortices in plasma contain an electric
current circulating around the center of the vortex, which generates a magnetic
field localized inside. Using computer simulations, we demonstrate that the
magnetic field associated with the vortex gives rise to a mechanism of
dissipation of the vortex pair in a collisionless plasma, leading to fast
annihilation of the magnetic field with its energy transforming into the energy
of fast electrons, secondary vortices, and plasma waves. Two major contributors
to the energy damping of double vortex system, namely, magnetic field
annihilation and secondary vortex formation, are regulated by the size of the
vortex with respect to the electron skin depth, which scales with the electron
gamma-factor, , as . Magnetic field
annihilation appears to be dominant in mildly relativistic vortices, while for
the ultrarelativistic case, secondary vortex formation is the main channel for
damping of the initial double vortex system.Comment: 6 pages, 4 figure
Radiation Dominated Electromagnetic Shield
We analyze the collision of a high energy electron beam with an oscillating
electric and magnetic field configuration, which represents a three-dimensional
standing electromagnetic wave. The radiating electrons are stopped at the
distance of the order of or less than the electromagnetic wave wavelength, and
become trapped near the electric field local maxima due to the nonlinear
dependence of the radiation friction force on the electromagnetic field
strength, while the quantum effects on the radiation friction remain
negligible.Comment: 8 pages, 5 figures, 31 citations, 1 appendi
On the interaction of the electromagnetic radiation with the breaking plasma waves
An electromagnetic wave (EMW) interacting with the moving singularity of the
charged particle flux undergoes the reflection and absorption as well as
frequency change due to Doppler effect and nonlinearity. The singularity
corresponding to a caustic in plasma flow with inhomogeneous velocity can arise
during the breaking of the finite amplitude Langmuir waves due to nonlinear
effects. A systematic analysis of the wave-breaking regimes and caustics
formation is presented and the EMW reflection coefficients are calculated.Comment: 13 pages, 5 figures, two appendice
Explosion of relativistic electron vortices in laser plasmas
The interaction of high intensity laser radiation with underdense plasma may
lead to the formation of electron vortices. Though being quasistationary on an
electron timescales, these structures tend to expand on a proton timescale due
to Coloumb repulsion of ions. Using a simple analytical model of a stationary
vortex as initial condition, 2D PIC simulations are performed. A number of
effects are observed such as vortex boundary field intensification, multistream
instabilities at the vortex boundary, and bending of the vortex boundary with
the subsequent transformation into smaller electron vortices
Electron dynamics, gamma and electron-positron production by colliding laser pulses
The dynamics of an electron bunch irradiated by two focused colliding
super-intense laser pulses and the resulting gamma and electron-positron
production are studied. Due to attractors of electron dynamics in a standing
wave created by colliding pulses the photon emission and pair production, in
general, are more efficient with linearly polarized pulses than with circularly
polarized ones. The dependence of the key parameters on the laser intensity and
wavelength allows to identify the conditions for the cascade development and
gamma-electron-positron plasma creation
Stochastic Regimes in the Driven Oscillator with a Step-Like Nonlinearity
A nonlinear oscillator with an abruptly inhomogeneous restoring force driven
by an uniform oscillating force exhibits stochastic properties under specific
resonance conditions. This behaviour elucidates the elementary mechanism of the
electron energization in the strong electromagnetic wave interaction with thin
targets.Comment: 10 pages, 12 figure
Enhancement of maximum attainable ion energy in the radiation pressure acceleration regime using a guiding structure
Radiation Pressure Acceleration relies on high intensity laser pulse
interacting with solid target to obtain high maximum energy, quasimonoenergetic
ion beams. Either extremely high power laser pulses or tight focusing of laser
radiation is required. The latter would lead to the appearance of the maximum
attainable ion energy, which is determined by the laser group velocity and is
highly influenced by the transverse expansion of the target. Ion acceleration
is only possible with target velocities less than the group velocity of the
laser. The transverse expansion of the target makes it transparent for
radiation, thus reducing the effectiveness of acceleration. Utilization of an
external guiding structure for the accelerating laser pulse may provide a way
of compensating for the group velocity and transverse expansion effects.Comment: 6 pages, 4 figure
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