4,822 research outputs found
Dynamics and control of the expansion of finite-size plasmas produced in ultraintense laser-matter interactions
The strong influence of the electron dynamics provides the possibility of
controlling the expansion of laser-produced plasmas by appropriately shaping
the laser pulse. A simple irradiation scheme is proposed to tailor the
explosion of large deuterium clusters, inducing the formation of shock
structures, capable of driving nuclear fusion reactions. Such a scenario has
been thoroughly investigated, resorting to two- and three-dimensional
particle-in-cell simulations. Furthermore, the intricate dynamics of ions and
electrons during the collisionless expansion of spherical nanoplasmas has been
analyzed in detail using a self-consistent ergodic-kinetic model. This study
clarifies the transition from hydrodynamic-like to Coulomb-explosion regimes
Controlled Shock Shells and Intracluster Fusion Reactions in the Explosion of Large Clusters
The ion phase-space dynamics in the Coulomb explosion of very large ( atoms) deuterium clusters can be tailored using two consecutive
laser pulses with different intensities and an appropriate time delay. For
suitable sets of laser parameters (intensities and delay), large-scale shock
shells form during the explosion, thus highly increasing the probability of
fusion reactions within the single exploding clusters. In order to analyze the
ion dynamics and evaluate the intracluster reaction rate, a one-dimensional
theory is used, which approximately accounts for the electron expulsion from
the clusters. It is found that, for very large clusters (initial radius
100 nm), and optimal laser parameters, the intracluster fusion yield becomes
comparable to the intercluster fusion yield. The validity of the results is
confirmed with three-dimensional particle-in-cell simulations.Comment: 25 pages, 11 figures, to appear in Physical Review
Laser-Cluster-Interaction in a Nanoplasma-Model with Inclusion of Lowered Ionization Energies
The interaction of intense laser fields with silver and argon clusters is
investigated theoretically using a modified nanoplasma model. Single pulse and
double pulse excitations are considered. The influence of the dense cluster
environment on the inner ionization processes is studied including the lowering
of the ionization energies. There are considerable changes in the dynamics of
the laser-cluster interaction. Especially, for silver clusters, the lowering of
the ionization energies leads to increased yields of highly charged ions.Comment: 10 pages, 11 figure
Dynamics of heterogeneous clusters under intense laser fields
We study the dynamics of atomic and molecular nano-clusters exposed to short
and intense X-fel pulsesComment: PhD Thesis, 133 pages, 60 (low quality) figure
Electron-ion coupling in semiconductors beyond Fermi's golden rule
In the present work, a theoretical study of electron-phonon (electron-ion)
coupling rates in semiconductors driven out of equilibrium is performed.
Transient change of optical coefficients reflects the band gap shrinkage in
covalently bonded materials, and thus, the heating of atomic lattice. Utilizing
this dependence, we test various models of electron-ion coupling. The
simulation technique is based on tight-binding molecular dynamics. Our
simulations with the dedicated hybrid approach (XTANT) indicate that the widely
used Fermi's golden rule can break down describing material excitation on
femtosecond time scales. In contrast, dynamical coupling proposed in this work
yields a reasonably good agreement of simulation results with available
experimental data
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