100-TW femtosecond laser based on parametric amplification

In experiments on the parametrical amplification of femtosecond pulses in wide-aperture DKDP crystals, a power of more than 100 TW has been reached, which is much higher than the record level achieved in such lasers. The energy efficiency obtained for the parametric amplifier is equal to 27%. The energy of a 72-fs pulse is equal to 10 J.     

Backscattering of a high-intensity ultrashort laser pulse from a solid target at oblique incidence

The results of experimental measurement and analytical estimation of the coefficient of backward reflection from targets made of various materials upon their irradiation by a picosecond laser pulse having the intensity of (0.8–4) × 10¹⁸ W/cm² are presented. It is shown that the induced surface instability leads to the formation of a profile backscattering the incident radiation. The coefficient of backward reflection achieves a few percent and has an intensity optimum depending on the target material.     

Generation of a fast-ion beam upon the interaction of a multiterawatt picosecond laser pulse with a solid target

The parameters of fast particles generated upon the interaction of 10¹⁹ W/cm² laser pulses with solid targets are studied. The spatial and energy parameters of fast ions are investigated. It is found that approximately 1–3% of the laser energy is transformed to the energy of mega-and submegaelectronvolt ions at laser pulse intensities ≥10¹⁸ W/cm². It is shown experimentally that an ion beam is directed perpendicular to the target surface. The analytic and numerical simulations agree with experimental results and predict the propagation of fast electrons in the mirror direction with respect to the incident laser beam and of ions perpendicular to the target. The theoretical calculations are compared with the experimental output and spectra of fast electrons and ions.     

Search for De-excitation of the 186mRe and 110mAg Nuclear Isomers in Plasma of High-Power Picosecond Laser Pulse

Physics of Atomic Nuclei - The possibility of observing the stimulated de-excitation of nuclear isomers (SDENI) in plasma (plasma lifetime ∼1.5 ps, temperature of electrons ∼ 10 keV)...     

Measurement of the SBS gain of radiation in glasses

A method for determining the specific gain under conditions of stimulated Brillouin scattering (SBS) is proposed, which is based on measuring the amplification of a Stokes beam with an inhomogeneous spatial intensity distribution in a sample used as an SBS amplifier. Under the same experimental conditions, the values of the SBS gain are obtained for the new phosphate glass KGSS 0180 (g = 1.9 cm/GW) and for the GLS 22 (g = 1.4 cm/GW), K8 (g = 1.3 cm/GW), and KU2 (g = 1.5 cm/GW) glasses, which are widely used in laser systems. The SBS frequency shift of radiation with a wavelength of 1.054 μm (14.57±0.02 GHz) and the hypersonic velocity (5030 m/s) have been determined for the KGSS 0180 glass by optical heterodyning. The relaxation time of hypersound in the noted media is estimated.     

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.     

Hard X radiation and fast particles in laser plasma experiments at laser intensities of up to 5×1018 W/cm2 on the target surface

Results are presented from an investigation of the hard X-ray spectrum and the parameters of fast particles in experiments on the interaction of laser pulses with solid targets in the PROGRESS-P facility at laser intensities of up to 5×10¹⁸ W/cm² on the target surface. The maximum energy of fast electrons obtained from direct measurements is found to be 8–10 MeV.