Nonlinear electrodynamics of the interaction of ultra-intense laser pulses with a thin foil

An analytical description of the interaction of laser light with a foil, described as a thin slab of overdense plasma, is presented together with the results of multidimensional particle in cell simulations. The matching conditions at the foil result in nonlinear boundary conditions for the wave equation. The conditions for relativistic transparency are given. The interaction with the foil leads to shaping of the laser pulse. In the case of oblique incidence of a relativistically intense pulse, nonlinear coupling modifies the pulse polarization and causes emission of high harmonics and generation of an electric current. Strong focalization of the reflected pulse, in particular in three-dimensional simulations, is observed for normal and oblique incidence due to the induced distortion of the foil surface. (C) 1998 American Institute of Physics. [S1070-664X(98)03507-1]

Small-scale electron density and magnetic-field structures in the wake of an ultraintense laser pulse

We investigate the interaction of a high intensity ultrashort laser pulse with an underdense collisionless plasma in the regime where the Langmuir wake wave excited behind the laser pulse is loaded by fast particle beams, formed during the wake wave breaking. The beam loading causes the deterioration of the central part of the wake wave near the pulse axis, and the formation of bunches of sharply focalized ultrarelativistic electrons. The bunches of electrons generate a fast propagating magnetic field, which we interpret in terms of the magnetic component of the Lienard-Wiechert potential of a moving electric charge. [S1063-651X(99)06611-8]

Surface oscillations in overdense plasmas irradiated by ultrashort laser pulses

The generation of electron surface oscillations in overdense plasmas irradiated at normal incidence by an intense laser pulse is investigated. Two-dimensional (2D) particle-in-cell simulations show a transition from a planar, electrostatic oscillation at 2 omega, with omega the laser frequency, to a 2D electromagnetic oscillation at frequency w and wave vector k > omega /c. A new electron parametric instability, involving the decay of a 1D electrostatic oscillation into two surface waves, is introduced to explain the basic features of the 2D oscillations. This effect leads to the rippling of the plasma surface within a few laser cycles, and is likely to have a strong impact on laser interaction with solid targets

Laser acceleration of charged particles in inhomogeneous plasmas .1.

The interaction of a laser pulse with a thin high-density plasma slab (foil) is proposed as a mechanism for producing laser pulses with the appropriate shape (sharp leading and/or rear edges). Such a pulse is optimum for the excitation of high-amplitude wake fields in underdense plasmas. It is shown (analytically and via particle-in-cell numerical simulations) that a phase-stable regime of unlimited particle acceleration can be realized in inhomogeneous plasmas

Parametric generation of surface deformations in laser interaction with overdense plasmas RID B-1900-2009

By analytical modeling and numerical simulation, we show that surface modes in moderately overdense plasmas may be excited parametrically by an intense, ultrashort laser pulse. This process has a feedback effect on fast electron generation and may seed a fast distortion of plasma "moving mirrors.

Nonlinear electromagnetic phenomena in the relativistic interaction of ultrahigh intensity laser pulses with plasmas

2D, low-frequency, relativistic solitary waves have been found recently in 2D. Particle-in-cell simulations of ultra-intense laser pulses propagating in underdense plasmas, in regimes where the laser pulse undergoes energy depletion and downshifting of its frequency. These slowly propagating, spatially localized, electromagnetic structures represent an important channel of energy conversion from the laser pulse to the plasma. Pulse energy can also be converted into fast propagating structures, associated with collimated beams of ultrarelativistic electrons. Lienard-Wiechert magnetic field structures have been observed in PIC simulations to move together with focalized ultrarelativistic electron beams in the plasma

Ion acceleration regimes in underdense plasmas

Acceleration of large populations of ions up to high (relativistic) energies may represent one of the most important and interesting tools that can be provided by the interaction of petawatt laser pulses with matter. In this paper, the basic mechanisms of ion acceleration by short laser pulses are studied in underdense plasmas. The ion acceleration does not originate directly from the pulse fields, but it is mediated by the electrons in the form of electrostatic fields originating from channeling, double layer formation, and Coulomb explosion

Interaction of petawatt laser pulses with underdense plasmas

Results are presented from analytical study and particle-in-cell simulations of the interaction of ultrashort petawatt laser pulses with underdense plasmas. It is shown that this interaction exhibits effects typical of the interaction of moderate-power pulses with overdense plasmas. The results obtained demonstrate relativistic self-focusing, the formation of a vacuum channel in a plasma, excitation of a superstrong longitudinal electric field, acceleration of ions and electrons up to ultrarelativistic energies, and generation of a quasistatic magnetic field. The generation of relativistic electromagnetic solitons is demonstrated. It is shown that a significant part of the laser-pulse energy is transformed into the energy of these solitons. The space and time dependences of the fields inside the solitons are found to agree with our analytical description

Laser acceleration of charged particles in inhomogeneous plasmas II: Particle injection into the acceleration phase due to nonlinear wake wave-breaking

Results from analytical studies and computer simulations of the nonlinear evolution of wake waves in inhomogeneous plasmas are presented. It is shown that the wake wave-breaking that appears due to the inhomogeneity of the Langmuir frequency can be used to inject electrons into the acceleration phase of the wave. In the wake wave excited behind a finite-width laser pulse, the wave-breaking mechanism involves the increase in the curvature of the wake front with the distance from the pulse, followed by the self-intersection of the electron trajectories