A method of wide-range X-ray and electron spectrometry of plasma formed by a femtosecond laser pulse with a peak intensity of over 1018 W/cm2 on the surface of a solid-state target is experimentally considered. Measurements of a flow of charged particles and quanta were carried out using thermoluminescent detectors based on LiF(Mg, Ti) that accumulate a dose, in front of which magnets were additionally installed to isolate the X-ray component. The spectra were obtained on the basis of the method for determining the accumulated dose of a detector depending on the thickness of the filter installed in front of it. The data have been restored in the range from 10 keV to several megaelectronvolts. The “temperatures” of the hot electron components of laser plasma have been determined, which are 160 and 1500 keV and may be related to the effects of particle acceleration in the dense-plasma region, as well as the temperatures during propagation of radiation in a cloud of subcritical density.

A technique based on thermoluminescent LiF(Mg,Ti) lithium fluoride detectors has been developed to study the spectral composition of X-ray radiation of femtosecond laser plasma in a wide range of photon energies from 1 keV to almost 1 MeV. This technique has been experimentally tested together with matrix-type semiconductor detectors. The plasma parameters have been measured under the action of a femtosecond pulse with a peak intensity of 1018 W/cm2 on a metal (copper) target, and good agreement is demonstrated between data from different detector types in terms of determining both the spectrum shape and the coefficient of the laser-pulse energy conversion into an X-ray flux. The temperature of hot electrons has been estimated, and its value exceeds 100 keV. The X-ray flux of copper K-lines, which exceeds 109 per shot, has been determined. The advantages and drawbacks of techniques for measuring spectra in problems of laser-plasma interaction are considered.

To study the spatial distribution of the intensity of an X-ray source of electric discharge plasma, a new-type coded aperture, which is a structure of intersecting mutually perpendicular transparent and opaque strips with the widths selected using a random number generator, has been used. The radiation passed through the coded aperture has produced a complex pattern of the coded image, which has been recorded on a Fuji TR fluorescent imaging plate without a protective coating. A mathematical procedure based on the iterative method of solving an incorrectly posed problem given by the Fredholm integral equation of the first kind has been applied to reconstruct the spatial distribution of plasma radiation intensity from this pattern. It has been shown that the use of the coded aperture not only has increased significantly the light intensity of the recording system in comparison with a pinhole camera, but also has made it possible to obtain a spatial resolution of the discharge plasma no worse than the resolution of the pinhole camera. The applicability of the developed iterative method for both sources close to point ones and extended emitting objects has been demonstrated.

Experiments on compression of cascade tungsten wire arrays with reduced inductance at the final stage of pinching aimed at increasing the specific concentration of plasma energy of the high-current Z‑pinches were carried out. The experiments were conducted at the Angara-5-1 facility at load current of up to 4 MA. The highest radiation power per unit pinch length were obtained using the cascade wire arrays in which mass per unit length of the inner wire array with reduced inductance was in the range between 1 and 1.5 that of the outer wire array. The soft X-ray radiation power of P 11 TW was obtained from the 1-cm-long pinch. The specific yield of the soft X-ray radiation was in the range of 130–140 kJ/cm. The total and specific powers of the pinch radiation obtained upon compression of the cascade load with reduced inductance exceeded the total and specific powers of the pinch radiation obtained by compression of a “standard” wire array with a length of 1.6 cm with the same parameters (7–8 TW and 5 TW/cm, respectively). The yield of the soft X-ray radiation did not change upon reduction in the length of the emitting pinch from 1.6 to 0.6 cm. The compression dynamics of such a load is indicative of an increased role played by the magnetic field of the current flowing in the inner cascade in interaction of the cascades. A variant of using interaction of the cascade-array shells via the magnetic field of the inner-cascade current as applied to the scheme of the statistical “hohlraum” with indirect irradiation of spherical targets is proposed. The scheme enables entrainment of part of the current by the inner wire array that confines the statistical “hohlraum.” In this case, interaction of cascades allows using nearly entire kinetic energy of the accelerated outer shell for generation of radiation in the statistical “hohlraum” by two forming near-electrode pinches.

Results of experimental investigation of charged particles generation and X-ray emission under relativistic interaction of laser pulse with $\left(\mathrm{C}_{2} \mathrm{H}_{6}\right) \mathrm{N}$ clusters are presented. Energy spectra of protons, ions and electrons are examined, revealing few hundreds of MeV particles.

To study the spatial distribution of the soft X-ray radiation intensity of a laser-produced plasma, a new type of coded aperture was used. This aperture is a structure with a mutually perpendicular arrangement of opaque strips, the distances between which and their widths were calculated with the use of a random number generator. The radiation transmitted through such aperture gives an intricate pattern of the encoded image, which was recorded on a Fuji TR imaging plate without a protective coating. To reconstruct the spatial distribution of the plasma radiation intensity from this pattern, a mathematical algorithm was developed that is an iterative method for solving an ill-posed problem—the Fredholm integral equation of the first kind. It has been shown that the use of the coded aperture not only enhances the efficiency of the registration system by many times but also allows one to get a spatial resolution no worse than in the case of the use of a pinhole camera. It is established that the developed iterative method can be used both for sources which differ little from point sources and for spatially extended objects.

The X-ray emission of relativistic laser plasma was investigated in the spectral range from XUV to gammas by a set of detectors and techniques. Thermal and hot electron components generation was studied in dependence of the peak laser intensity and contrast of the laser pulse.

The work is devoted to experimental study of soft x-ray radiation spectra of laser-produced plasma in a wide spectral range of 5-100Å at the Kamerton facility (GPI) with pulse duration 70 ps, pulse energy 1-5J, and wavelength 0.53 microns at which the laser intensity (power flux density) of 7×10^{14}-3.5×10^{15}W/cm^{2} was achieved. A spectrograph was used, which had transmission diffraction gratings with a ratio of the elementary gap to the period of the structure of 0.25 and 0.41. Detection was performed on both UV-4 x-ray photo film and Fuji TR fluorescent imaging plate. Solid samples from Al, Si, Ti, Cu, Ta, and W were used as targets. The ionization states of the plasma corresponding to various electron temperatures were calculated, which made it possible to estimate the electron temperature by comparison of these calculation results with the experimentally obtained spectra. The estimated electron temperature, which depends on the laser pulse energy and the target material, varied within the range 100-450eV. To verify the correctness of the temperature estimations obtained by such comparison a numerical simulation of plasma radiation was carried out by the use of prismspect computer program. It was found that the results of this simulation are in good agreement with estimations on the base of experimentally obtained spectra. The analysis of these spectra showed that tantalum, tungsten, or titanium targets are the best candidates among the tested ones for the use of laser-produced plasma as a radiation source in the "water window" spectral range (23-44Å) for applications in biology and medicine.

The results of experiments on increasing the specific energy density of high-current Z-pinch plasma by using various compression modes are presented. The experiments were carried out with cascade wire cylindrical loads at the Angara-5-1 facility with a current in the load of up to 4 MA. The experiments used loads both with a reduced inductance at the final stage of pinch compression and loads that make it possible to implement a transient compression mode from a cascade scheme to a composite Z-pinch scheme. When cascade arrays, which have a reduced inductance at the final stage of compression, are compressed, the specific power of soft X-ray emission is higher than 5 TW/cm, which corresponds to the radiation power with a pinch of a standard length of 1.6 cm at the level of 8–9 TW. The specific total X-ray emission yield is about 150 kJ/cm for a total emission yield at a level of 90–95 kJ. The compression dynamics of such a load indicates a significant role of the magnetic field of the current flowing through the inner cascade in the interaction of the cascades. It is shown that in the transient compression mode from a cascade array to a composite Z‑pinch, the outer array of a material with a relatively low atomic number (Al) provides a high kinetic energy flux density, while the inner array of a small diameter made from a material with a high atomic number (W) allows one to increase the radiation power three times.

A review of an edition of the diary of a prominent figure in the Vilna (Vilnius) cooperative Alexander Szklennik, which he began keeping a few months before the German occupation of the city and before the November Revolution in Germany. The manuscript of the diary was donated 15 years after the author's death by his relatives to the Vilna Association of Friends of Science. Its publication was carried out by Dr Joanna Gierowska-Kallaur. The published diary is the only such comprehensive and stunningly accurate picture at the disposal of historians of everyday life in Vilna during the German occupation. The picture of the real situation in Vilna and the Vilna region in 1915-1918 remained unclear for a long time, due to the one-sidedness of Polish historiography, the influence of German and Lithuanian historical politics and the myth of the foundation of the Belarusian People's Republic. For Polish historiography, the most significant factor limiting the possibility of a reliable historical analysis of the situation in Vilna was the lack of access for Polish historians to the sources remaining in << archival dispersal >> outside Poland. The diary's text, replete with details of everyday life in the city and descriptions of political disagreements between the national communities (Poles, Lithuanians, Belarusians and Jews), makes it possible to recreate a comprehensive picture of life in the city during the occupation period.

The characteristics of x-ray radiation of a target that is bombarded by a beam of accelerated electrons ejected by a low-power vacuum discharge with laser ignition are studied. It is shown that the maximum radiation energy exceeds the applied potential difference across the discharge gap by almost an order of magnitude and is inversely proportional to the mass of the cathode material ablated by laser radiation. The energy spectrum of x-ray radiation reconstructed from the radiation attenuation curve by filters-absorbers of various thicknesses showed that in the maximum acceleration mode the average energy of the main part of the spectrum is more than four times higher than the voltage across the discharge gap at the moment of beam emission. Possible mechanisms providing anomalous acceleration of electrons in the discharge are considered.

A review of an edition of the diary of a prominent figure in the Vilna (Vilnius) cooperative Alexander Szklennik, which he began keeping a few months before the German occupation of the city and before the November Revolution in Germany. The manuscript of the diary was donated 15 years after the author’s death by his relatives to the Vilna Association of Friends of Science. Its publication was carried out by Dr Joanna Gierowska-Kałłaur. The published diary is the only such comprehensive and stunningly accurate picture at the disposal of historians of everyday life in Vilna during the German occupation. The picture of the real situation in Vilna and the Vilna region in 1915–1918 remained unclear for a long time, due to the one-sidedness of Polish historiography, the influence of German and Lithuanian historical politics and the myth of the foundation of the Belarusian People’s Republic. For Polish historiography, the most significant factor limiting the possibility of a reliable historical analysis of the situation in Vilna was the lack of access for Polish historians to the sources remaining in «archival dispersal» outside Poland. The diary’s text, replete with details of everyday life in the city and descriptions of political disagreements between the national communities (Poles, Lithuanians, Belarusians and Jews), makes it possible to recreate a comprehensive picture of life in the city during the occupation period.

Porous materials have many applications for laser–matter interaction experiments related to inertial confinement fusion.Obtaining new knowledge about the properties of the laser-produced plasma of porous media is a challenging task. In this work, we report, for the first time to the best of our knowledge, the time-dependent measurement of the reflected light of a terawatt laser pulse from the laser-produced plasma of low-Z foam material of overcritical density. The experiments have been performed with the ABC laser, with targets constituted by foam of overcritical density and by solid media of the same chemical composition. We implemented in the MULTI-FM code a model for the light reflection to reproduce and interpret the experimental results. Using the simulations together with the experimental results, we indicate a criterion for estimating the homogenization time of the laser-produced plasma, whose measurement is challenging with direct diagnostic techniques and still not achieved.

It is shown experimentally that a low-power pinch vacuum discharge with laser ignition can emit a beam of abnormally accelerated electrons with maximum energies per unit charge, almost an order of magnitude higher than the voltage across the discharge gap. It is established that the intensity of the X-ray radiation generated by the action of the beam on the target significantly decreases with increasing laser pulse energy. Maximum energy of X-ray quanta is inversely proportional to the mass of the cathode material ablated by laser radiation when the discharge is ignited. Possible mechanisms of the electron beam generation process are discussed.

It has been experimentally shown that a low-power vacuum pinch discharge with laser ignition can emit a beam of abnormally accelerated electrons with maximum energies per unit charge almost an order of magnitude higher than the voltage across the discharge gap. It has been found that the intensity of the X-ray radiation generated when the beam is applied to the target significantly decreases with an increase in the laser pulse energy. The maximum energy of X-ray quanta is inversely proportional to the mass of the cathode substance ablated by laser radiation during discharge ignition. Possible mechanisms of the electron-beam generation process have been discussed.

The results of studies of the soft x-ray and extreme ultraviolet (SXR/EUV) radiation of thin flat aluminum foils and wires under the explosion in an electric discharge on the compact high-current KING generator are presented. These studies were based on the SXR/EUV spectroscopy with a spectral resolution of 6 angstrom, a temporal resolution of 5 ns and a spatial resolution of 200 mu m. To study the plasma radiation of exploded foils and wires in the SXR/EUV range, we used a transmission diffraction grating spectrograph which in combination with two additional slits provided spectral and spatial resolution. The spectrograph was coupled with a four-frame recorder based on a microchannel plate for providing temporal resolution. The analysis and comparison of the spectral, spatial, temporal, and energy characteristics of the SXR/EUV radiation of plasma formed under the explosion of foils and wires of a similar mass made of aluminum was carried out. The spectra were calculated as well and the plasma parameters and their changes in time and space were estimated on the basis of these calculations and comparison with relevant experimental results. Experiments have shown that when foils explode, a single intense source of SXR/EUV radiation is formed with radiated energy in the range of 10-20 J and a power of up to 100 MW in the quantum energy range from 30 to 250 eV. At the same time, the radiation power under the explosion of foils turned out to be about twice above the power under the explosion of wires of comparable mass.