Laser-driven vacuum breakdown waves.

It is demonstrated by three-dimensional quantum electrodynamics - particle-in-cell (QED-PIC) simulations that vacuum breakdown wave in the form of QED cascade front can propagate in an extremely intense plane electromagnetic wave. The result disproves the statement that the self-sustained cascading is not possible in a plane wave configuration. In the simulations the cascade is initiated during laser-foil interaction in the light sail regime. As a result, a constantly growing electron-positron plasma cushion is formed between the foil and laser radiation. The cushion plasma efficiently absorbs the laser energy and decouples the radiation from the moving foil thereby interrupting the ion acceleration. The models describing propagation of the cascade front and electrodynamics of the cushion plasma are presented and their predictions are in a qualitative agreement with the results of numerical simulations.

Probing non-perturbative QED with electron-laser collisions.

The vast majority of QED results are obtained in relatively weak fields and so in the framework of perturbation theory. However, forthcoming laser facilities providing extremely high fields can be used to enter not-yet-studied regimes. Here, a scheme is proposed that might be used to reach a supercritical regime of radiation reaction or even the fully non-perturbative regime of quantum electrodynamics. The scheme considers the collision of a 100 GeV-class electron beam with a counterpropagating ultraintense electromagnetic pulse. To reach these supercritical regimes, it is unavoidable to use a pulse with ultrashort duration. Using two-dimensional particle-in-cell simulations, it is therefore shown how one can convert a next-generation optical laser to an ultraintense (I ≈ 2.9 × 1024 Wcm-2) attosecond (duration ≈ 150 as) pulse. It is shown that if the perturbation theory persists in extreme fields, the spectrum of secondary particles can be found semi-analytically. In contrast, a comparison with experimental data may allow differentiating the contribution of high-order radiative corrections if the perturbation theory breaks.

Two-screen single-shot electron spectrometer for laser wakefield accelerated electron beams.

The laser wakefield acceleration electron beams can essentially deviate from the axis of the system, which distinguishes them greatly from beams of conventional accelerators. In case of energy measurements by means of a permanent-magnet electron spectrometer, the deviation angle can affect accuracy, especially for high energies. A two-screen single-shot electron spectrometer that correctly allows for variations of the angle of entry is considered. The spectrometer design enables enhancing accuracy of measuring narrow electron beams significantly as compared to a one-screen spectrometer with analogous magnetic field, size, and angular acceptance.

Laser field absorption in self-generated electron-positron pair plasma.

Recently, much attention has been attracted to the problem of limitations on the attainable intensity of high power lasers [A. M. Fedotov et al., Phys. Rev. Lett. 105, 080402 (2010)]. The laser energy can be absorbed by electron-positron pair plasma produced from a seed by a strong laser field via the development of the electromagnetic cascades. The numerical model for a self-consistent study of electron-positron pair plasma dynamics is developed. Strong absorption of the laser energy in self-generated overdense electron-positron pair plasma is demonstrated. It is shown that the absorption becomes important for a not extremely high laser intensity I ∼ 10(24) W/cm(2) achievable in the near future.

Carrier-envelope phase effects in plasma-based electron acceleration with few-cycle laser pulses.

Carrier-envelope phase effects during the interaction of relativistically intense few-cycle laser pulses with a plasma are studied in the ''bubble'' regime when an electron cavity (bubble) is formed behind the pulse. We show that for few-cycle laser pulses the cavity shape becomes asymmetric and depends strongly on the carrier-envelope phase. The carrier-envelope phase varies when the laser pulse propagates in plasma, which causes transverse oscillations of the cavity. Furthermore, the beam of electrons trapped by the cavity becomes modulated in the polarization plane. To describe these effects we derive an analytical model extended beyond the ponderomotive approximation. The degree of plasma cavity asymmetry as a function of the laser-plasma parameters is calculated. The obtained results are verified by particle-in-cell simulations.