Breakdown of argon by a train of high-repetition long-wave-infrared pulses from a free-electron laser oscillator.

This study presents an experimental demonstration of laser-induced breakdown in argon, employing a free-electron laser with a wavelength of 10 μm and a repetition rate of 2.856 GHz. Despite the fluence of individual laser pulses being an order of magnitude smaller than the breakdown threshold, cascade ionization developed in the pulse train, leading to breakdown.

Enhanced ion acceleration from transparency-driven foils demonstrated at two ultraintense laser facilities.

Laser-driven ion sources are a rapidly developing technology producing high energy, high peak current beams. Their suitability for applications, such as compact medical accelerators, motivates development of robust acceleration schemes using widely available repetitive ultraintense femtosecond lasers. These applications not only require high beam energy, but also place demanding requirements on the source stability and controllability.

Relativistic flying forcibly oscillating reflective diffraction grating.

Relativistic flying forcibly oscillating reflective diffraction gratings are formed by an intense laser pulse (driver) in plasma. The mirror surface is an electron density singularity near the joining area of the wake wave cavity and the bow wave; it moves together with the driver laser pulse and undergoes forced oscillations induced by the field. A counterpropagating weak laser pulse (source) is incident at grazing angles, being efficiently reflected and enriched by harmonics.

4π-spherically focused electromagnetic wave: diffraction optics approach and high-power limits.

The focused field and its intensity distribution achieved by the 4π-spherical focusing scheme are investigated within the framework of diffraction optics. Generalized mathematical formulas describing the spatial distributions of the focused electric and magnetic fields are derived for the transverse magnetic and transverse electric mode electromagnetic waves with and without the orbital angular momentum attribute. The mathematical formula obtained shows no singularity in the field in the focal region and satisfies the finite field strength and electromagnetic energy conditions.

High-contrast high-intensity repetitive petawatt laser.

We report the generation of 63 J of broadband pulse energies at 0.1 Hz from the J-KAREN-P laser, which is based on an OPCPA/Ti:sapphire hybrid architecture. Pulse compression down to 30 fs indicates a peak power of over 1 PW.

Possible Precise Measurement of Delbrück Scattering Using Polarized Photon Beams.

The advent of high-flux-polarized γ-ray sources makes possible the nearly isolated precise measurement of the vacuum contribution, Delbrück scattering, to the elastic scattering of these photons off nuclei. Because of the fact that the elastic scattering of the photons is a coherent summation of four processes and that up to now unpolarized sources have been used, the isolated measurement of Delbrück scattering has not been performed. We show that for the appropriate choice of scattering angles, photon polarization, and energies this scattering can be measured nearly independently of other scattering processes.

High-power γ-ray flash generation in ultraintense laser-plasma interactions.

When high-intensity laser interaction with matter enters the regime of dominated radiation reaction, the radiation losses open the way for producing short pulse high-power γ-ray flashes. The γ-ray pulse duration and divergence are determined by the laser pulse amplitude and by the plasma target density scale length. On the basis of theoretical analysis and particle-in-cell simulations with the radiation friction force incorporated, optimal conditions for generating a γ-ray flash with a tailored overcritical density target are found.

Lorentz-Abraham-Dirac versus Landau-Lifshitz radiation friction force in the ultrarelativistic electron interaction with electromagnetic wave (exact solutions).

When the parameters of electron-extreme power laser interaction enter the regime of dominated radiation reaction, the electron dynamics changes qualitatively. The adequate theoretical description of this regime becomes crucially important with the use of the radiation friction force either in the Lorentz-Abraham-Dirac form, which possesses unphysical runaway solutions, or in the Landau-Lifshitz form, which is a perturbation valid for relatively low electromagnetic wave amplitude. The goal of the present paper is to find the limits of the Landau-Lifshitz radiation force applicability in terms of the electromagnetic wave amplitude and frequency.

Schwinger limit attainability with extreme power lasers.

High intensity colliding laser pulses can create abundant electron-positron pair plasma [A. R. Bell and J.