The results of flyer acceleration up to the velocity of 10 km/s at the Angara-5-1 facility at the current of 5 MA by the magnetic field pressure are presented. 1D and 2D simulation of aluminum flyer acceleration is performed. The simulation results agree with each other and with the experimental data.

Spectral properties of the high-temperature plasma obtained by exposing a nickel layer to a source of high-power X-ray radiation (a power of 6–10 TW with a duration of 7–10 ns) based on a Z-pinch, formed during implosion of tungsten multi-wire arrays at the Angara-5-1 facility, are studied. In this case, the Z‑pinch radiation heats the target and turns it into the hot plasma, and the same radiation probes the target plasma to determine the spectral dependence of the transmission of this plasma. An original scheme is proposed for measuring the incident, transmitted and self-emission of a target simultaneously in one experiment in the frame mode using a grazing incidence diffraction spectrograph. Using laser shadow imaging, experimental data are obtained on the velocity of the plasma expansion on the irradiated and back sides of the target, which reached 100 km/s. Targets made of thin Ni layers deposited on a mylar film are studied. An irradiation-induced multiple increase in the transmission of the target plasma in the EUV range is observed compared to the transmittance of the target in the cold state. The dependence of the absorption spectrum of the plasma and the accompanying self-radiation of the target on the power and shape of the heating pulse is studied. The measurement results are compared with numerical calculations performed using the RALEF-2D two-dimensional radiation code, which has been repeatedly used previously to simulate similar experiments. The shape of the spectral dependence of the transmission in the experiment and calculation is similar in the range of ∼30–200 Å, but the model plasma transmission (∼0.8–0.9) is higher than that obtained using a spectrograph and X-ray multi-frame photography (∼0.5–0.6).

The results of experiments on the study of the generation of high-power pulsed soft X-ray (SXR) emission with a photon energy higher than 100 eV (in the spectral range with wavelengths λ shorter than 120 Å) during the plasma implosion of nested arrays of mixed composition with different ratios of array radii carried out on a pulse power facility Angara-5-1 with a discharge current level of up to 3.5 MA are presented. The outer array consisted of fibers of a substance with a low atomic number (plastic), and the inner array consisted of a substance with a high atomic number (tungsten, W). In the case of nested arrays of this design, a significant increase in the peak SXR power was obtained compared to single tungsten arrays with the same parameters as for the tungsten array in the inner array. By optimizing the linear mass of the outer array and the ratio of array radii, powerful SXR pulses were prepared with a high pulse power up to 18 TW, pulse energy of ~140 kJ and short pulse duration of ~5 ns. It is shown that by optimizing the linear mass of the outer array (fiber array) it is possible to achieve ~90% conversion of the electromagnetic energy pumped into the vicinity of the array into X-ray emission pinch energy. In this case, the fraction of the kinetic energy of the plasma implosion into the emission energy is not higher than 30%. In shots optimal over the output SXR power, an increase in the fraction of the X-ray emission energy in the spectral range of λ ∈ (30, 40) Å was recorded that is 30–100% than that in single tungsten arrays with similar parameters.

A digital model of a grazing-incidence X-ray spectrograph and methods for reconstruction of soft X-ray spectra of a Z-pinch plasma at the Angara-5-1 facility in the 2–40 nm range have been developed. The main problems hindering reliable qualitative and quantitative reconstruction of the initial Z-pinch X-ray spectra are the superposition of signals from different diffraction orders and the complex form of the device instrumental function. Two techniques for reconstructing the spectrum are presented. In the first one, a digital model of the spectrograph was developed in the Geant4 Monte Carlo simulation toolkit, taking into account the geometry of the experiment and the processes of interaction of X-ray radiation with a diffraction grating. In this model, taking into account the specific shape of the groove profile of the diffraction grating and the differential method for solving the diffraction problem, the X-ray intensity distribution in different diffraction orders depending on the wavelength is calculated. Using the developed model of the spectrograph, its instrumental function was calculated. The second technique does not use a specific grating groove shape, but, based on the analysis of calibration spectrograms, it constructs a dispersion relation and allows one to reconstruct the spectrum. At the end of the work, the results of reconstruction by the first and second techniques are compared and fairly good agreement between the spectra obtained by different techniques is shown.

Numerical modeling of the processes occurring in a cathode of vacuum transmission line during the passage of a powerful current pulse has been performed. The main parameters used in the numerical model correspond to the data of experiments carried out at the Angara-5-1 facility.

The results of experiments on the study of plasma compression of nested wire arrays of mixed composition and the generation of powerful pulses of soft x-ray radiation (SXR), carried out on a pulse power facility Angara-5-1 at a current level of up to 3 MA, are presented. Based on the latest experimental data on the intensity of plasma formation of various substances m ˙ (in μ g(cm 2 ns) −1 ) (Mitrofanov et al 2020 Plasma Phys. Rep. 46 1150–80) and on the features of the dynamics of plasma compression in nested arrays (Mitrofanov et al 2018 Plasma Phys. Rep. 44 203–35), a nested wire array design has been developed which makes it possible to obtain a high peak SXR power in comparison with the known designs of single and nested tungsten wire arrays. During the implosion of nested arrays of mixed composition, consisting of plastic fibers and tungsten wires, shorter and more powerful SXR pulses were obtained with a maximum peak power P SXR max ∼ 10 TW with a full width at half maximum (FWHM) duration of ∼5 ns compared to the parameters of SXR pulses upon compression of single tungsten arrays: P SXR max ∼ 5 TW and FWHM ∼ 10 ns. Thus, under the conditions of our experiments, we have shown the possibility of a twofold increase in the peak SXR power during compression of nested arrays by optimizing their design.

In the high-current Z-pinch technique, energy is transferred to the load via vacuum lines with magnetic self-isolation. Plasma is formed on the electrodes of these lines. The plasma formation process near the radiating Z-pinch is enhanced due to irradiating the electrodes by soft x-ray radiation (SXR). Evaporation of thin organic films (an oil layer from diffusion pumps) also leads to early plasma formation before the powerful SXR pulse occurs.

The results of experiments on the effect of soft X-ray radiation (SXR) on thin mylar films of micron thickness are presented. The main result of the research is the development and testing of an adaptive filter-a filter made of mylar (hereinafter, My) film with time-varying transparency. This film is necessary for profiling the multi-terawatt soft X-ray radiation pulse in the experiments on radiation ablation of the targets made of layers of some metals (e.g., Al, Ni, In, Sn, Au, Bi, etc.), currently being carried out at the Angara-5-1 facility. Such a film absorbs almost all the energy of the preliminary pulse (the so-called "pre-pulse") and becomes "transparent" by the time the main terawatt radiation pulse occurs. The distance between this film and the target under study is chosen so as not to damage the target by the spreading filter substance during its radiation heating. Thus, the target layer initial density at the time of its irradiation by the main SXR radiation pulse will increase significantly. The use of an adaptive filter makes it possible to determine the change in the target layer transparency in a wider range of the initial values of its density and to reduce the influence of the target expansion dynamics on the accuracy of measuring its spectral transparency.

At the Angara-5-1 installation the experiments were carried out to study the processes occurring during the passage of current in a vacuum transporting line in which the cathode was protected by a ceramic coating. The linear current density was about 1–2 MA/cm; the time of the current rise to the maximum was ~100 ns. It is shown that in the case of coating the MITL cathode with ceramics, not all the current entering the MITL reaches its end.

— In electromagnetic generators of the terawatt range with current pulse of 1–30 MA, electric explosion of the surface of current-carrying electrodes takes place. One of the options for protecting the electrodes is covering the current-carrying surface with different materials. In this work, we present experimental data and results of numerical simulations of the processes that take place in a thick-walled heterophase electrode during the passage of current with a high linear density. The amplitude value of the linear current density in the simulations was of 2.8 MA/cm. The results of the simulations of the processes that occur in the electrodes during the passage of current with high linear density are in qualitative agreement with experimental data.

Experiments aimed at investigation of X-ray self-emission of plasma of heated targets consisting of layers of different materials (Mylar, polypropylene, In, Sn, and Au) exposed to the action of energy flux of X‑ray radiation (the so-called energy exposure of the target) of up to 10 kJ/cm2 were carried out. A Z-pinch induced by implosion of a tungsten wire-array by current of up to 4 MA in Angara-5-1 facility was used as a source of high-power X-ray radiation. The temporal dynamics of intensity of self-emission of heated targets was studied. In the process, contribution of expanding layer of a material with high atomic number Z to self-emission of the target dominates that of a Mylar film with effective charge Zeff ≈ 4.5. It is demonstrated that the 1/e decay time of target emission depends on expansion dynamics of target plasma. The latter, in turn, depends on orientation of the layer characterized by high atomic number relative to the source of radiation. New data on spectral composition of self-emission of targets and its changes with time is obtained. This data is compared with the results of numerical simulation of target heating and scatter by means of RALEF-2D two-dimensional radiation gas-dynamic code.

The paper presents the results of experiments with the compression of the plasma of double multiwire arrays of mixed composition and the generation of powerful soft X-ray radiation (SXR) pulses carried out on the powerful electrophysical facility Angara-5-1 at a discharge current of up to 3 MA. Based on the latest experimental data on the production rate $$\dot {m}$$ of different plasmas (in μg/(cm2 ns)) [1] and on specificities of the dynamics of plasma compression in nested arrays [2], a nested array was designed, which makes it possible to obtain a high SXR peak power in comparison with the optimal (in terms of radiation power) designs of single and nested tungsten wire arrays. By selecting substances with different plasma production rates, it was possible to reduce the level of magnetohydrodynamic instabilities at the final stage of compression of the inner array. This made it possible to reduce the radiation pulse duration and increase the SXR power. Using implosion of nested arrays of mixed composition, consisting of plastic fibers and tungsten wires, shorter and more powerful SXR pulses with a maximum peak power $$P_{{{\text{SXR}}}}^{{{\text{max}}}}$$ ~10 TW with a pulse duration FWHM ~ 5 ns were obtained, compared to the parameters of SXR pulses upon compression of single tungsten arrays: $$P_{{{\text{SXR}}}}^{{{\text{max}}}}$$  ~ 5 TW and FWHM ~ 10 ns. Thus, we have shown the possibility of a twofold increase in the peak SXR power during compression of nested arrays under the conditions of our experiments by optimizing their design. One of the results of this work was finding the optimal parameters of the nested arrays and the prediction of the peak SXR power for experiments at powerful electrophysical facilities, differing from with substantially different levels of discharge current, 4–26 MA (Angara-5-1, Julong-1, and ZR).

Compression of a fiber array with a deuterated target mounted on its axis is studied at the Angara-5-1 facility (3.5 MA, 100 ns). Cylindrical arrays with an initial diameter of 12 mm made from polypropylene fibers with a diameter of 13.4 µm are used. The number of fibers varied from 30 to 120. The target with the density of 0.08–0.2 g/cm3 and the diameter of 1 mm was made on the basis of deuterated polyethylene. A 10‑frame ultra-high-speed X-ray camera, optical slit scans, an integral X-ray pinhole camera, vacuum X-ray diodes, a crystal spectrograph, and neutron detectors are used to measure the plasma parameters in the Z‑pinch. It is found that the dynamics of plasma compression and evolution of local plasma formations, which are sources of neutrons and soft X-ray emission in the energy range of E > 150 eV, depend on the load configuration: the number of fibers, diameter, and density of the deuterated target. Efficient compression of the liner plasma, high concentration and temperature of the compressed target state, as well as the highest neutron yield (8 × 109 neutron/pulse) are observed in experiments with arrays with the fiber number of 60, inside which the target with the diameter of 1 mm and density of 0.2 g/cm3 was placed. The electron density and temperature of the hot plasma in local formations are estimated as ne ≈ 1021 cm–3, Te ≈ 1 keV, respectively. The average neutron energy was 2.6 ± 0.2 MeV. The intensity of the plasma formation $$\dot {m}$$ [in µg/(cm2 ns)] of polypropylene fibers under the action of the discharge current of the facility is determined in experiments with fiber arrays.