Alexander A. Andreev

Short light pulse amplification and compression by stimulated Brillouin scattering in plasmas in the strong coupling regime

Short light pulse amplification using the stimulated Brillouin backscattering mechanism is considered. The novel feature is that the interaction process takes place in the strongly coupled regime and therefore the pulse compression is not limited by the ion-acoustic wave period. The mechanism is very efficient due to the large ratio of light frequency to the characteristic ion-acoustic wave frequency. Although large-amplitude ion-acoustic waves are generated and subsequent wave breaking takes place, the fluid and kinetic nonlinearities do not intervene with the amplification itself.

Efficient generation of fast ions from surface modulated nanostructure targets irradiated by high intensity short-pulse lasers

It’s shown that the imposition of sub-laser wavelength relief structures on the surface of mass-limited-targets results into several folds higher short-pulse laser absorption, and consequently the efficient generation of fast ions. The optimum relief parameters for enhanced short-pulse laser absorption and higher ion acceleration are estimated numerically by particle-in-cell simulations and then corroborated by analytical scalings. The stability of the pre-imposed surface modulation during the laser pulse foil interaction is also examined.

Enhancement of laser/EUV conversion by shaped laser pulse interacting with Li-contained targets for EUV lithography

The advantages of droplet and claster Li-contained targets for debris free EUV generation are estimated on base of analytical modeling and simulation. Conversion efficiency of laser energy into EUV energy from such targets is found to reach a few percents. The laser prepulse is proposed to enhance the laser energy conversion into emission at wavelength of 13.5 nm.

Optimal lithium targets for laser-plasma lithography

Lithium containing droplet and cluster targets irradiated by laser pulses are proposed as prospective source of for soft x-ray lithography. Analytical model and simulations show that laser with repetition rate of several MHz with energy of several mJ and pulse duration 10 ps is required.

Optimal proton acceleration from lateral limited foil sections and different laser pulse durations at relativistic intensity

The proton acceleration from a thin foil irradiated by a laser pulse at relativistic intensities is a process highly dependent on the electron dynamic at the rear side of the foil. By reducing the lateral size of the laser irradiated foil the hot electrons are confined in a small volume leading to an enhancement of both the maximum proton energy and the conversion efficiency in the target normal sheath acceleration regime. In this paper we demonstrate that an optimal lateral size of the target can be found. While a smaller target surface leads to a better hot electron confinement and enhances the Debye sheath accelerating the protons, it also leads to an increase of preplasma formation due to limited laser contrast available experimentally and hence to a decrease of the proton acceleration. The experimentally found optimum is in good agreement with analytic theory and 2D particle in cell simulations. In addition, the maximum proton energy as a function of pulse duration has been investigated. The experime...

Effect of plasma inhomogeneity on ion acceleration when an ultra-intense laser pulse interacts with a foil target

Fast electrons generated via the interaction of ultra-intense laser pulses with a solid target can produce multi-MeV ions from laser-induced plasmas. These fast ions can be used for various applications ranging from the ion implantation to the stimulation of nuclear reactions. The most important point here is the efficiency of production of such fast ions. We analyse in detail, with the help of an analytical model and particle-in-cell simulations, the most efficient acceleration mechanisms including the ponderomotive force driving and acceleration by the shock wave, and compare the electrostatic ion acceleration at the front side and at the rear side of a foil target. We also determine the optimal plasma density distribution shaped by the laser pre-pulse.

Backscattering of ultrashort high intensity laser pulses from solid targets at oblique incidence

Backreflection of short, intense laser pulses at oblique incidence on solid targets is explained with a model where a periodic electron density modulation acts as a diffraction grating. The pump and reflected electromagnetic waves drive through the ponderomotive force the grating, and the coupled system becomes parametrically unstable. The basic equations governing this situation are given. A linearized stability analysis is used to obtain the instability growth rate in a homogeneous plasma and the convective gain coefficients for the inhomogeneous case. The results support the feasibility of the suggested mechanism. An absolute instability is predicted to set on at a threshold intensity of about 1016u200aW/cm2 for a typical laser pulse with a length of 100 fs and a spot size of 30 μm. The instability is shown to saturate at a level of a few percent, because the higher harmonics in the electron density modulation make the diffraction more diffuse, thus reducing both the ponderomotive force and the backreflect...

Narrow-directed fast-ion flow generation from targets irradiated by a picosecond laser pulse

The proton and deuteron yields from thin targets irradiated by a picosecond laser pulse with an average radiation intensity of ≤4×1018 W/cm2 at the target were measured in the megaelectron-volt energy range. A ring structure was observed for the outgoing ions, and the angular ion-beam divergence was found to be extremely small (0.5°). The fast-ion generation mechanism allowing for the appearance of ring structure is discussed, and the characteristic energies and spatioangular ion-beam distribution are estimated.

Conversion of ultrashort laser pulses into x-ray emission in high-density laser plasma

Various regimes of interaction of ultrashort laser pulses with solid targets in vacuum are analyzed. Analytical formulas that characterize plasma parameters and x-ray emission during the laser pulse are obtained in a very broad range of experimental parameters. For constant laser energy, the conversion efficiency into x rays during laser pulse is shown to grow with laser pulse length in all interaction regimes.

Efficiency of thermonuclear burning in laser targets with spark ignition

Numerical simulation of thermonuclear flash with isobaric ignitor for laser spherical targets with different dimensions and temperatures are performed and the target energy gain as a function of ignitor parameters is obtained. As a result the requirements for ignitor parameters are elaborated under which the spark ignition provides an essential increase in the gain as compared with volume ignition. Calculations are carried out with the use of TERA code based upon self-consistent solution for system of kinetic equations for thermonuclear particles and radiation, obtained by the Monte Carlo method, and of hydrodynamic equations.