Fundamental Physics and Relativistic Laboratory Astrophysics with Extreme Power Lasers

The prospects of using extreme relativistic laser-matter interactions for laboratory astrophysics are discussed. Laser-driven process simulation of matter dynamics at ultra-high energy density is proposed for the studies of astrophysical compact objects and the early universe.Comment: 12 pages, 15 figures. Invited talk at European Conference on Laboratory Astrophysics (ECLA), 26-30 September, 2011, Paris, France. Submitted to European Astronomical Society Publications Serie

Bow wave from ultra-intense electromagnetic pulses in plasmas

We show a new effect of the bow wave excitation by an intense short laser pulse propagating in underdense plasma. Due to spreading of the laser pulse energy in transverse direction, the bow wave causes a large-scale transverse modulation of the electron density. This can significantly increase the electric potential of the wake wave since the wake wave is generated in the region much wider than the laser pulse waist.Comment: 6 pages, 4 figure

On annihilation of the relativistic electron vortex pair in collisionless plasmas

In contrast to hydrodynamic vortices, vortices in plasma contain an electric current circulating around the center of the vortex, which generates a magnetic field localized inside. Using computer simulations, we demonstrate that the magnetic field associated with the vortex gives rise to a mechanism of dissipation of the vortex pair in a collisionless plasma, leading to fast annihilation of the magnetic field with its energy transforming into the energy of fast electrons, secondary vortices, and plasma waves. Two major contributors to the energy damping of double vortex system, namely, magnetic field annihilation and secondary vortex formation, are regulated by the size of the vortex with respect to the electron skin depth, which scales with the electron gamma-factor, $\gamma_e$, as $R/d_e \propto \gamma_e^{1/2}$. Magnetic field annihilation appears to be dominant in mildly relativistic vortices, while for the ultrarelativistic case, secondary vortex formation is the main channel for damping of the initial double vortex system.Comment: 6 pages, 4 figure

Relativistic Whistle: High Order Harmonics Induced by the Ultra-Intense Laser Pulse Propagating inside the Fiber

A propagation of an ultra-intense short laser pulse in a fiber is investigated with two dimensional Particle-in-Cell simulations. The fiber is a narrow hollow channel with walls consisting of overdense plasma. In the nonlinear interaction of the laser pulse with fiber walls high order harmonics are generated. Sufficiently high harmonics, for which the fiber walls are transparent, propagate outwards at certain angle. This is a scheme of a generator of ultra-short pulses of coherent light with a very short wavelength.Comment: 6 pages, 6 figure

Radiation Dominated Electromagnetic Shield

We analyze the collision of a high energy electron beam with an oscillating electric and magnetic field configuration, which represents a three-dimensional standing electromagnetic wave. The radiating electrons are stopped at the distance of the order of or less than the electromagnetic wave wavelength, and become trapped near the electric field local maxima due to the nonlinear dependence of the radiation friction force on the electromagnetic field strength, while the quantum effects on the radiation friction remain negligible.Comment: 8 pages, 5 figures, 31 citations, 1 appendi

On the interaction of the electromagnetic radiation with the breaking plasma waves

An electromagnetic wave (EMW) interacting with the moving singularity of the charged particle flux undergoes the reflection and absorption as well as frequency change due to Doppler effect and nonlinearity. The singularity corresponding to a caustic in plasma flow with inhomogeneous velocity can arise during the breaking of the finite amplitude Langmuir waves due to nonlinear effects. A systematic analysis of the wave-breaking regimes and caustics formation is presented and the EMW reflection coefficients are calculated.Comment: 13 pages, 5 figures, two appendice

Explosion of relativistic electron vortices in laser plasmas

The interaction of high intensity laser radiation with underdense plasma may lead to the formation of electron vortices. Though being quasistationary on an electron timescales, these structures tend to expand on a proton timescale due to Coloumb repulsion of ions. Using a simple analytical model of a stationary vortex as initial condition, 2D PIC simulations are performed. A number of effects are observed such as vortex boundary field intensification, multistream instabilities at the vortex boundary, and bending of the vortex boundary with the subsequent transformation into smaller electron vortices

Electron dynamics, gamma and electron-positron production by colliding laser pulses

The dynamics of an electron bunch irradiated by two focused colliding super-intense laser pulses and the resulting gamma and electron-positron production are studied. Due to attractors of electron dynamics in a standing wave created by colliding pulses the photon emission and pair production, in general, are more efficient with linearly polarized pulses than with circularly polarized ones. The dependence of the key parameters on the laser intensity and wavelength allows to identify the conditions for the cascade development and gamma-electron-positron plasma creation

Stochastic Regimes in the Driven Oscillator with a Step-Like Nonlinearity

A nonlinear oscillator with an abruptly inhomogeneous restoring force driven by an uniform oscillating force exhibits stochastic properties under specific resonance conditions. This behaviour elucidates the elementary mechanism of the electron energization in the strong electromagnetic wave interaction with thin targets.Comment: 10 pages, 12 figure

Enhancement of maximum attainable ion energy in the radiation pressure acceleration regime using a guiding structure

Radiation Pressure Acceleration relies on high intensity laser pulse interacting with solid target to obtain high maximum energy, quasimonoenergetic ion beams. Either extremely high power laser pulses or tight focusing of laser radiation is required. The latter would lead to the appearance of the maximum attainable ion energy, which is determined by the laser group velocity and is highly influenced by the transverse expansion of the target. Ion acceleration is only possible with target velocities less than the group velocity of the laser. The transverse expansion of the target makes it transparent for radiation, thus reducing the effectiveness of acceleration. Utilization of an external guiding structure for the accelerating laser pulse may provide a way of compensating for the group velocity and transverse expansion effects.Comment: 6 pages, 4 figure