Контроль внутренней температуры активных элементов (АЭ) мощных лазеров необходим для их безопасной работы. В статье описана методика и устройство для мониторинга внутренней температуры АЭ лазеров. Измерения основаны на импульсном ультразвуковом (УЗ) зондировании и зависимости от температуры скорости звука в материале АЭ. Изменение скорости звука приводит к изменению фазы УЗ сигнала, прошедшего через объект, которое регистрируется описываемым устройством. Представлены результаты мониторинга температуры АЭ с помощью ультразвукового зондирования в процессе работы действующей лазерной установки.

We present the first experimental results obtained with a setup created on the basis of the PEARL laser facility for studying the processes of generating terahertz radiation from laser wake fields which are formed during the propagation of a high-power femtosecond laser pulse in a rarefied plasma. In particular, the occurrence of terahertz generation in the case where the laser–plasma interaction region is located between a pair of dielectric prisms of total internal reflection is demonstrated. The dependence of the terahertz radiation energy on the energy of a femtosecond laser pulse and on the plasma density is studied.

Laser wakefield acceleration of electrons is studied experimentally in the strongly mismatched regime. Up to 20 J, 60 fs laser pulses are focussed at the input of a gas cell with thef/46 focussing system. The resulting 44 mu m focal spot at the cell entrance is about two times greater than the matched spot size. Experimental results are supported by 3D particle-in-cell (PIC) simulations of the laser-plasma dynamics as well as by numerical simulations of the gas distribution inside the gas cell. Special attention is paid to the accuracy of spectra reconstruction affected by low pointing stability of the accelerated electron beam. It is demonstrated experimentally that the electron energy in the mismatched regime can be higher than that in the matched one and can reach GeV level for the used laser parameters.

Compression of a 12-J laser pulse from 63 to 21 fs is experimentally demonstrated for a beam 18 cm in diameter. The compression is implemented for a pulse freely propagating in glass under conditions of self-phase modulation and subsequent compensation for dispersion under reflection front dispersion mirrors. This simple and inexpensive technique for increasing multiply the pulse power is characterised by almost 100% energy efficiency and can be used at the output of ally ultra-high-power laser, without any changes in its optical scheme.

Compression of pulsed Nd : glass laser radiation under stimulated Brillouin scattering (SBS) in perfluorooctane is investigated. Compression of 16-ns pulses at a beam diameter of 30 mm is implemented. The maximum compression coefficient is 28 in the optimal range of laser pulse energies from 2 to 4 J. The Stokes pulse power exceeds that of the initial laser pulse by a factor of about 11.5. The Stokes pulse jitter (fluctuations of the Stokes pulse exit time from the compressor) is studied. The rms spread of these fluctuations is found to be 0.85 ns.

A superbright X-ray source with a radiation temperature of ~1.2 keV making it possible to create a solid-state plasma whose kinetics is determined by the radiative processes has been implemented under the impact of a 170-TW pulse of the PEARL femtosecond laser facility on an aluminum target with submicron thickness. The diagnostics of the created plasma is performed by X-ray spectral methods using spectral transitions in hollow multicharged ions.

Amplifiers based on neodymium phosphate glass rods 60 - 100 mm in diameter are experimentally studied. The amplifiers are pumped by INP-16/250 tubular flash lamps placed in a universal pump cavity with a two-section mirror reflector. A compact high-voltage capacitive energy storage with a preionisation circuit was developed to supply the lamps.