We outline the results of experiments in the generation of X-ray laser radiation on the 4d-4p Ni-like ion transitions at a wavelength lambda = 189 angstrom under sequential irradiation of plane targets by two laser pulses focused to a line. These experiments were executed on the Sokol-p picosecond laser facility. The average energy of a 4-ps long ultrashort pump pulse was equal to 6.5 J, the energy of a 0.44-ns long prepulse was equal to 2.7 J, and the time delay between them was equal to 1.5 ns. The effective gain for short target lengths was equal to similar to 24 cm(-1). In the travelling pump wave regime, which was realised using a ladder mirror, we obtained an 8-fold increase in output X-ray laser energy in comparison with the output energy obtained in the ordinary target irradiation regime.

A technology of depleted uranium thin films, which can be used as high-reflectivity X-ray mirrors at a wavelength of 4.5 nm, is presented. The coefficient of X-ray reflection by these mirrors varies from 90 to 10% at grazing angles between 1° and 10°. The stability of the reflection coefficients for 200-Å-thick depleted uranium films covered by a protective carbon layer 100 and 200 Å in thickness and for 200-Å-thick uranium-nickel films with a nickel content of 9 and 23 wt % is studied. A high-reflectivity mirror is fabricated with the goal of increasing the X-ray radiation intensity in RKK-1-100 X-ray calibration equipment. Advice on fabrication of X-ray mirrors based on depleted uranium films is given.

The transient collisional excitation (TCE) scheme was used to obtain generation of X-ray laser radiation on the 3p-3s transitions of the Ne-like Ti-ions at 10 TW SOKOL-P laser developed at RFNC-VNIITF. The Nd-laser light was focused in a line with length from 2 up to 8 mm and width of 30 microns. Two successive pulses irradiated the polished Ti-slab. The duration of prepulse was equal to 400 ps and a pumping pulse had duration of 4 ps; the delay between pulses equals to 1.5 ns. The Nd-laser energy was about of 10 J and the ratio of energy in prepulse and basic pulses was equal to 1:2. The grating spectrometer equipped with a focusing mirror and CCD detector was used for measurement of the X-ray laser line at 32.6 nm. A small signal gain about of 30 cm-1 was obtained in experiments with target length from 2 up to 4 mm. The 32.6 nm line radiation with energy about of 1 ¼J and divergence of 9 mrad were registered in SOKOL-P experiments with target length of 8 mm.

Results are presented from experimental investigations of the angular distributions and energy spectra of fast ions produced in deuterium polyethylene targets under irradiation by picosecond laser pulses with intensities of up to 2 × 10 18 W/cm 2 in the SOKOL-P facility. The parameters of ion fluxes were measured by time-of-flight spectrometers based on semiconductor detectors.

Results are presented from experiments on the laser generation of X-ray radiation at the wavelength λ=469 Å (ε=26.4 eV) on the 3p(J=0)−3s(J=1) transition of Ne-like Ar ions. Experiments were carried out on the SIGNAL electrophysical facility with a 3.1-mm-diameter 157-mm-long Al2O3 ceramic capillary filled with argon at a pressure of 0.2–1.0 Torr. The discharge current amplitude was I ∼ 25–40 kA, the current rise rate being dI/dt ∼ 1012 A/s. By a vacuum X-ray diode tuned to detect X-ray photons with energies in the range 10–40 eV, laser pulses with a duration of t1 ∼ 1 ns and maximum energy of E1,max ∼ 1 µJ were recorded. The pulses were generated 35 ns after the discharge current was switched on. The line spectra in the wavelength range of 150–500 Å showed the bright λ=469 Å line. The angular divergence of the generated X-ray laser beam was estimated to be Δϑ ∼ 2 mrad.

The results of experimental studies of the X-ray lasing on the 3p—3s transitions of neon-like titanium ions are presented. The laser radiation at 1.054 μm was focused to a ∼30-μm wide line of length from 2 to 8 mm. Plane polished titanium plates were successively irradiated by two pulses: a 400-ps prepulse and a 4-ps main pump pulse delayed by 1.5 ns relative to the prepulse. The total laser energy was 8–10 J. The nanosecond-to-picosecond pulse energy ratio was maintained constant and was equal to 1:3. For a short target length (from 2 to 4 mm), the 326-Å line intensity was experimentally observed to grow exponentially with length. The small-signal gain for the X-ray laser radiation is estimated at approximately 30 cm-1. The X-ray laser beam divergence was equal to about 9 mrad.

Experimental results on fast neutron generation in D(d,n) 3 He and T(d,n) 4 He reactions in the SOKOL-P laser facility [1] are presented. Solid targets were irradiated by 1.054 μm, s- or p-polarized laser pulses of energy 5-8 J on target and duration 0.85-2 ps. The peak laser intensity was 0.5-2·10 18 W/cm 2 . Flat deuterated plastic (CD 2 ) n targets and D α T β targets were used in experiments. Some experiments were carried out with additional targets placed in front of and behind the laser target. The used (TOF) time-of-flight technique helped identify neutrons from D(d,n) 3 He and T(d,n) 4 He reactions. Yields up to 10 6 DD-neutrons and 10 7 DT-neutrons were measured. Interaction of the fast ion beam with the target can explain the observed yield.

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 5×10 18 W/cm 2 on the target surface. The maximum energy of fast electrons obtained from direct measurements is found to be 8–10 MeV.

The results of recent laser-solid interaction experiments carried out at the PROGRESS-P facility are described for the following parameters of laser radiation: lambda = 1.053 mu m, energy up to 500 mJ, pulse duration similar to 2 ps, focal spot diameter of 20 mu m. The spectrum of soft X-ray (epsilon < 1.5 keV) and the hard X-ray (epsilon=5 divided by 80 keV) were measured for solid targets from Al, glass, Ta used in these experiments. The fast electrons temperature is estimated to be about of 10 keV. The soft X-ray spot size about of 20 mu m was measured by pinhole camera. The X-ray lines of He-like Al ions were registered by the spectrometer using plane gypsum crystal.

The interaction of high-intensity, picosecond, 1.06 mu m laser pulses at peak intensity up to 4.10(17) W/cm(2) with solid metal targets is studied by measurements of the absorption and fast particle generation with Ulbricht sphere and time-of-flight charge collectors and X-ray spectrometer measurements Measurements are presented for both s and p-polarization.

The effect of a prepulse with a rising amplitude on the absorption and compression of microspheres filled with the DT gas was investigated for ratios of the power of a prepulse to the power of the main pulse in the range 10 − 9–10 − 4. The experiments were carried out using the PROGRESS laser facility (λ = 1.06 μm, q≤2 × 1015 W/cm2). An increase of the relative power of a prepulse from 10 − 8 to 10 − 6–10 − 4 reduced the absorption coefficient by a factor of 1.5–2 and increased the degree of compression by a factor of 2–3. An analytic model allowing for the influence of a prepulse was developed. The experimental results were compared with the model calculations.

An investigation was made of the limitation coefficient ƒ of the electron thermal conductivity of a laser plasma formed as a result of spherical irradiation of a target using the 6-beam Progress laser facility (λ = 1.054 μm) at heating radiation power densities of q ~ (0.5–5) × 1015 W/cm2. The value of ƒ was determined by comparing the results of measurements of the energy absorbed by the target, the average target compression rate, and the yield of x-ray lines of multiply charged Si ions with the results of numerical calculations carried out using the Zarya program in a wide range of ƒ. It was found that ƒ decreased on increase in q.

The six-beam Progress laser facility was used in a study of compression and heating of glass microbubbles filled with a DT gas and coated outside by a thin (~0.1?) aluminum film. The power density of Nd laser radiation (?=1.054?) reaching the target surface was (1?2)?1015 W/cm2 and the specific energy deposited in the target was 0.1-0.25 J/ng. Two-dimensional images of a laser plasma were recorded using x-ray lines of multiply charged Si and Al ions. Strong Al lines observed at distances close to the target center were evidence of a strongly unstable nature of compression of the laser plasma. This was confirmed also by a weak dependence of the neutron yield on the specific input energy, which did not agree with the results of one-dimensional calculations carried out using the Zarya program.