507 research outputs found
On extreme field limits in high power laser matter interactions: radiation dominant regimes in high intensity electromagnetic wave interaction with electrons
We discuss the key important regimes of electromagnetic field interaction
with charged particles. Main attention is paid to the nonlinear Thomson/Compton
scattering regime with the radiation friction and quantum electrodynamics
effects taken into account. This process opens a channel of high efficiency
electromagnetic energy conversion into hard electromagnetic radiation in the
form of ultra short high power gamma ray flashes.Comment: 15 pages, 10 figures, invited talk presented at the SPIE-2013
conference, Prague, Czech Republic, Apr. 15, 201
High Power Gamma-Ray Flash Generation in Ultra Intense Laser-Plasma Interaction
When high-intensity laser interaction with matter enters the regime of
dominated radiation reaction, the radiation losses open the way for producing
short pulse high power gamma ray flashes. The gamma-ray pulse duration and
divergence are determined by the laser pulse amplitude and by the plasma target
density scale length. On the basis of theoretical analysis and particle-in-cell
simulations with the radiation friction force incorporated, optimal conditions
for generating a gamma-ray flash with a tailored overcritical density target
are found.Comment: 12 pages, 5 figures Accepted for publication in Physical Review
Letters (this http://prl.aps.org/
Ensemble of ultra-high intensity attosecond pulses from laser-plasma interaction
The efficient generation of intense X-rays and -radiation is studied.
The scheme is based on the relativistic mirror concept, {\it i.e.}, a flying
thin plasma slab interacts with a counterpropagating laser pulse, reflecting
part of it in the form of an intense ultra-short electromagnetic pulse having
an up-shifted frequency. In the proposed scheme a series of relativistic
mirrors is generated in the interaction of the intense laser with a thin foil
target as the pulse tears off and accelerates thin electron layers. A
counterpropagating pulse is reflected by these flying layers in the form of an
ensemble of ultra-short pulses resulting in a significant energy gain of the
reflected radiation due to the momentum transfer from flying layers.Comment: 6 pages, 2 figures. Phys. Lett. A, in pres
Current sheets at three-dimensional magnetic nulls:effect of compressibility
The nature of current sheet formation in the vicinity of three-dimensional
(3D) magnetic null points is investigated. The particular focus is upon the
effect of the compressibility of the plasma on the qualitative and quantitative
properties of the current sheet. An initially potential 3D null is subjected to
shearing perturbations, as in a previous paper [Pontin et al., Phys. Plasmas,
in press (2007)]. It is found that as the incompressible limit is approached,
the collapse of the null point is suppressed, and an approximately planar
current sheet aligned to the fan plane is present instead. This is the case
regardless of whether the spine or fan of the null is sheared. Both the peak
current and peak reconnection rate are reduced. The results have a bearing on
previous analytical solutions for steady-state reconnection in incompressible
plasmas, implying that fan current sheet solutions are dynamically accessible,
while spine current sheet solutions are not.Comment: to appear in Physics of Plasmas. This version contains updated
figures and references, additional discussion, and typos are fixed. This is
the second in a series of papers - the first of which (by the same authors)
is located at astro-ph/0701462. A version with higher quality figures can be
found at http://www.maths.dundee.ac.uk/~dpontin
On the breaking of a plasma wave in a thermal plasma: I. The structure of the density singularity
The structure of the singularity that is formed in a relativistically large
amplitude plasma wave close to the wavebreaking limit is found by using a
simple waterbag electron distribution function. The electron density
distribution in the breaking wave has a typical "peakon" form. The maximum
value of the electric field in a thermal breaking plasma is obtained and
compared to the cold plasma limit. The results of computer simulations for
different initial electron distribution functions are in agreement with the
theoretical conclusions.Comment: 21 pages, 12 figure
Transverse Dynamics and Energy Tuning of Fast Electrons Generated in Sub-Relativistic Intensity Laser Pulse Interaction with Plasmas
The regimes of quasi-mono-energetic electron beam generation were
experimentally studied in the sub-relativistic intensity laser plasma
interaction. The observed electron acceleration regime is unfolded with
two-dimensional-particle-in-cell simulations of laser-wakefield generation in
the self-modulation regime.Comment: 10 pages, 5 figure
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