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

Partially ionized plasmas in electromagnetic fields

The interaction of partially ionized plasmas with an electromagnetic field is investigated using quantum statistical methods. A general statistical expression for the current density of a plasma in an electromagnetic field is presented and considered in the high field regime. Expressions for the collisional absorption are derived and discussed. Further, partially ionized plasmas are considered. Plasma Bloch equations for the description of bound-free transitions are given and the absorption coefficient as well as rate coefficients for multiphoton ionization are derived and numerical results are presented.Comment: 18 pages, 8 figures, accepted for publication in J. Phys.: Conf. Se

Local exchange-correlation vector potential with memory in Time-Dependent Density Functional Theory: the generalized hydrodynamics approach

Using Landau Fermi liquid theory we derive a nonlinear non-adiabatic approximation for the exchange-correlation (xc) vector potential defined by the xc stress tensor. The stress tensor is a local nonlinear functional of two basic variables - the displacement vector and the second-rank tensor which describes the evolution of momentum in a local frame moving with Eulerian velocity. For irrotational motion and equilibrium initial state the dependence on the tensor variable reduces to that on a metrics generated by a dynamical deformation of the system.Comment: RevTex, 5 pages, no figures. Final version published in PR

Harmonics generation in electron-ion collisions in a short laser pulse

Anomalously high generation efficiency of coherent higher field-harmonics in collisions between {\em oppositely charged particles} in the field of femtosecond lasers is predicted. This is based on rigorous numerical solutions of a quantum kinetic equation for dense laser plasmas which overcomes limitations of previous investigations.Comment: 4 pages, 4 eps-figures include

Non-instant collisions and two concepts of quasiparticle

The kinetic theory recently implemented in heavy ion reactions combines a non-local and non-instant picture of binary collisions with quasiparticle features. We show that the non-instant description is compatible with the spectral concept of quasiparticles while the commonly used variational concept is consistent only with instant collisions. The rearrangement energy, by which the variational concept surpasses the spectral one, is shown to be covered by a medium effect on non-instant collisions.Comment: PRE 59,1 rap. com

Quantum kinetics and thermalization in a particle bath model

We study the dynamics of relaxation and thermalization in an exactly solvable model of a particle interacting with a harmonic oscillator bath. Our goal is to understand the effects of non-Markovian processes on the relaxational dynamics and to compare the exact evolution of the distribution function with approximate Markovian and Non-Markovian quantum kinetics. There are two different cases that are studied in detail: i) a quasiparticle (resonance) when the renormalized frequency of the particle is above the frequency threshold of the bath and ii) a stable renormalized `particle' state below this threshold. The time evolution of the occupation number for the particle is evaluated exactly using different approaches that yield to complementary insights. The exact solution allows us to investigate the concept of the formation time of a quasiparticle and to study the difference between the relaxation of the distribution of bare particles and that of quasiparticles. We derive a non-Markovian quantum kinetic equation which resums the perturbative series and includes off-shell effects. A Markovian approximation that includes off-shell contributions and the usual Boltzmann equation (energy conserving) are obtained from the quantum kinetic equation in the limit of wide separation of time scales upon different coarse-graining assumptions. The relaxational dynamics predicted by the non-Markovian, Markovian and Boltzmann approximations are compared to the exact result. The Boltzmann approach is seen to fail in the case of wide resonances and when threshold and renormalization effects are important.Comment: 39 pages, RevTex, 14 figures (13 eps figures