Laser-electron interaction

Laser-electron interaction from classical electrodynamics... 

Let us first review some experiments in which the laser-driven acceleration of electrons has been obtained in laser-solid interactions. 

Because of their inertia, the effect on the ions of the high frequency electric field of the electron plasma waves dealt with so far averages out to zero. However, surprisingly, light ions and/or protons have been observed in ultrahigh intensity laser pulse interaction with solid targets since the late 1990s [33-36]. Later on, these particles were found to come from contaminant layers on... 

Models describing the transport of electrons in molecular junctions have been shown to be quite powerful. Here the emphasis was put on time-dependent effects which can, for example, be triggered by external laser fields. If these fields are strong, a non-perturbative treatment of the laser-matter interaction is of large importance and is included in the presented TL QME. Also the connection of transport through molecular wires or coherent laser control scenarios may play an important role in the future. 

In order to interpret the results of our experiments, optimal-control calculations were performed where a GA controlled 40 independent degrees of freedom in the laser pulses that were used in a molecular dynamics simulation of the laser-cluster interactions for Xejv clusters with sizes ranging from 108 to 5056 atoms/cluster. These calculations, which are reported in detail elsewhere [67], showed optimization of the laser-cluster interactions by a sequence of as many as three laser pulses. Detailed inspection of the simulations revealed that the first pulse in this sequence initiates the cluster ionization and starts the expansion of the cluster, while the second and third pulse optimize two mechanisms that are directly related to the behaviour of the electrons in the cluster. We consistently observe that the second pulse in the three-pulse sequence arrives a time delay where the conditions for enhanced ionization are met. In other words, the second pulse arrives at a time where the ionization of atoms is assisted by the proximity of surrounding ions. The third peak is consistently observed at a delay where the collective oscillation of the quasi-free electrons in the cluster is 7t/2 out of phase with respect to the driving laser field. For a driven and damped oscillator this phase-delay represents an optimum for the energy transfer from the driving force to the oscillator. 

Here A(t) denotes the vector potential of the laser field, p = (p1,p2) the final electron momenta, and k the drift momentum of the first electron in between ionization and recollision. The binding potential V of the first electron and the electron-electron interaction Vi2 enter (4.4) through their form factors... 

Wharton KB, Hatchett SP, Wilks SC, Key MH, Moody JD, Yanovsky V, Offen-berger AA, Hammel BA, Perry MD, Josi C (1998) Experimental measurements of hot electrons generated by ultraintense (> 1019 W/cm2) laser-plasma interactions on solid-density targets. Phys Rev Lett 81 822-825... 

Chen H, Soom B, Yaakobi B, Uchida S, Meyerhofer DD (1993) Hot-electron characterization from Ka measurements in high-contrast, p-polarized, picosecond laser-plasma interactions. Phys Rev Lett 70 3431-3434... 

Feurer T, Theobald W, Sauerbrey R, Uschmann I, Altenbernd D, Teubner U, Gibbon P, Foerster E, Milka G, Miquel JL (1997) Onset of diffuse reflectivity and fast electron flux inhibition in 528-nm-laser-solid interactions at ultrahigh intensity. Phys Rev E 56 4608-4614... 

The advent of relativistic electron beams generated from laser-plasma interactions opens the possibility of producing X-rays in the keV to 100 keV... 

Systematic investigations of the laser-cluster interaction were carried out by simultaneously measuring high-resolution X-ray emission spectra and ion energy spectra produced by the laser irradiation of micron-sized Ar clusters at laser intensities of 1018 to 1019 W/cm2. To suppress the creation of preplasma, we designed a special conical nozzle and eliminated the laser prepulse. The results indicate that the explosion time scale for micron-sized clusters is much longer than that for nanometer-sized clusters. It is found that hot electrons produced by a higher contrast pulse (a smaller prepulse) allow the isochoric... 

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