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We present data on the quasi-isentropic compressibility of a strongly coupled (nonideal) plasma of a deuterium–helium mixture in the range of pressures 150–250 GPa in devices with a cylindrical geometry and a new result obtained in an experiment with “pure” deuterium at a pressure ~200 GPa. The trajectory of the plasma-compressing metallic shells was recorded using powerful pulsed X-ray sources with a boundary electron energy up to 60 MeV. The densities of the plasma of deuterium and its mixture with helium were determined from the measured radii of the shells at the instant of their “stopping.” We derived the pressure of the compressed plasma based on gasdynamic computations including the real characteristics of the experimental devices. The data obtained confirm the conclusion previously reached at VNIIEF about a phase transition in the plasma of compressed deuterium in the range of pressures 150–160 GPa and suggest that this phase transition is retained in the mixture of deuterium with helium.

A nonideal helium plasma has been compressed to a density of ~9 g/cm3 by a pressure of P ~ 10000 GPa produced by an explosive charge of 85 kg of TNT in a spherical two-cascade device. The experiment has been performed on an X ray setup using simultaneously three betatrons with a boundary energy of about 60 MeV and a multichannel optoelectronic system of recording X-ray images. The pressure of the compressed helium has been determined from the gas-dynamic calculation.

Experiments were performed to study the spherical compression of deuterium and helium to pressures of ≈3000 GPa in a quasi-isentropic regime. The process was recorded by a multiframe radiographic system which produces up to nine x-ray images of a cavity with gas at different times in one experiment. X-ray images show that explosive devices provide a nearly spherically symmetric shape of the cavity with gas up to the maximum compression of the gas. The experimental data are in good agreement with the results of calculations using the equations of state of the gases studied. From the results of these calculations, the parameters of the region of the compressed gas states obtained in the experiments were determined: for deuterium, a density of 5.5 g/cm3 and a pressure of 3.6 TPa; for helium, a density of 4.7 g/cm3 and a pressure of 2.4 TPa.

For about 15 years, studies of fast gas-dynamic processes have been conducted at the Logunov Institute of Experimental Physics (VNIIEF) of the Russian Federal Nuclear Center using the proton radiography system developed jointly with the Logunov Institute of High Energy Physics on the basis of a U-70 accelerator. The main advantages of flash proton radiography over widely used flash x-ray radiography are high spatial resolution, multiframe mode, transmission capability, dynamic range of recording, etc. In recent years, effort has continued to extend the capabilities of the proton radiography system by increasing the total time and recording field and supplementing it with additional diagnostic techniques and new explosion-proof chambers. This paper presents the results of studies that illustrate these capabilities.

An experimental result for the quasi-isentropic compressibility of a strongly nonideal deuterium plasma compressed in a spherical device by the pressure P = 11400 GPa (114 Mbar) to the density ρ ≈ 10g/cm3 has been reported. The characteristics of the experimental device, diagnostic methods, and experimental results have been described. The trajectory of motion of metallic shells compressing a deuterium plasma has been recorded using intense pulsed sources of X rays with the boundary energy of electrons up to 60 MeV. The deuterium plasma density ρ ≈ 10g/cm3 has been determined from the measured radius of the shell at the time of its “stop.” The pressure of the compressed plasma has been determined from gas-dynamic calculations taking into account the real characteristics of the experimental device.

The thermodynamic parameters of a strongly nonideal helium plasma obtained in experimental devices of hemispherical and spherical geometries are presented. Under shock-wave loading in the hemispherical device, the helium plasma was compressed to a density ρ ≈ 0.76 g cm–3 by a pressure P ≈ 83 GPa at a temperature T ≈ 51000 K. Two-cascade spherical experimental devices of two types were used under quasi-isentropic helium plasma compression. In the devices of the first type at the same initial gas pressure in both cavities of the shells, the helium plasma was compressed approximately by a factor of 200 to a density ρ ≈ 8 g cm–3 by a pressure P ≈ 4800 GPa. In the devices of the second type at a ratio of the initial gas pressures in the cavities of about 9: 1, the thermodynamic parameters of a nonideal helium plasma compressed by a factor of 900 to a density ρ ≈ 5 g cm–3 by a pressure P ≈ 3700 GPa were determined. The compressed-plasma pressure was determined from the results of gasdynamic computations. An X-ray radiograph consisting of three betatrons and a multichannel optoelectronic X-ray imaging system was used to determine the positions of the boundaries of the gaseous-helium-compressing steel shell.

A model of frequency and time-domain Mossbauer forward scattering (FS) spectra on a magnetic target in the regime of RF hyperfine field reversals is proposed. The model allows us to describe the temperature dependence of RF effects in the FS frequency spectra of FeBO3 measured at temperatures below the Neel point (~348 K). In the proposed model, temporal (with internal mark) Mossbauer FS spectra on a magnetic target are calculated to study the dependence of the structure of these spectra on the target’s optical thickness, the degree of phase correlation of the RF hyperfine field reversals, and the value of the phase of the RF field used as an external parameter.

We report results from an experiment on Pb that we explosively shock loaded to $$P_{SL} \approx 32$$ - and 43-GPa, in a single experiment. These $$P_{SL}$$ caused the Pb sample to isentropically release to either a liquid or mixed solid–liquid phase post-shock. The post-shock sample damage and dynamics were diagnosed with proton radiography, which gave quantitative damage data within three distinct regions. The first region is the particle (ejecta) cloud, where we observed that total areal mass ejected from the shocked Pb surface is in-dependent of the peak $$P_{SL}$$ for unsupported (Taylor wave) shockwave loading. The second region, which exhibits spall and cavitation, distends and disperses as the shocked coupon self-similarly expands subsequent to the shockwave impulse and the release into tension. The third region includes undamaged, full density Pb sample. We report quantitative observations from all three regions, and we used the data to evaluate and validate damage and ejecta models, which satisfactorily describe the observed experimental dynamics.

This work presents the results of experiments on the compression of a spherical copper shell loaded by the detonation of a plastic explosive layer. A U-70 accelerator is used for radiographic recording of the convergence of the shell to the center, and metallographic analysis of the copper shell preserved after the experiment is performed. The results of multiframe proton radiography of the convergence of the inner boundary of the copper shell to the center are compared with the results of numerical simulations.

The quasi-isentropic compressibility of a nonideal helium plasma has been measured in a two-cascade spherical chamber with separated cavities with the use of an explosive charge with the mass of ≈55 kg. The experiment has been performed on an X-ray diffraction complex consisting of three betatrons and a multichannel optoelectronic system for recording X-ray images. The density of the compressed helium plasma measured at the initial pressures of the gas in the outer and inner cavities P1 = 36.4 MPa and P2 = 5.1 MPa, respectively, is ρ = 4.6 g/cm3, which corresponds to the degree of compression σ = 575 at pressure P≈3000 GPa under the condition of strong nonideality (γ ∼ 7) and noticeable degeneracy of electrons (nλ3 ∼ 5). The pressure of compressed helium has been determined from the results of the gas-dynamics calculation.

The quasi-isentropic compressibilities of deuterium and helium plasmas are measured in the pressure range 1500–5000 GPa at densities up to 8 g/cm3 using spherical experimental devices and an X-ray complex consisting of three betatrons and a multichannel optoelectronic system for taking X-ray images. The experimental results demonstrate the possibilities of high-energy-density experimental physics to reproduce the extreme states of substance typical of the Universe under laboratory conditions using the energy of traditional condensed explosives.

Predictive simulation of the long-term response of multilayer targets with ceramics layers to shock compression demands appropriate material models. Because ceramics are complex brittle materials, which tend to lose their strength under heavy loads, such simulation requires the failure models well-proven for a wide range of strains and strain rates. Standard plate impact experiments provide the main data utilized for developing and validating the mechanical models of material response to shock compression. However, apart from the fact that such experimental data are inherently one-dimensional, they can be insufficient to verify the failure model at relatively low strain rates typical for long unloading waves. Here, we present the experimental results for explosive compression of a spherical multilayer shell initiated by a single detonator. The explosive-coated shell consists of the nested spherical layers: the outer made of boron carbide and the inner of lead. X-ray images showing the evolution of those layers after detonation are then compared with simulation results. Propagation of the compression wave through the layers resulting in ceramics damage is analyzed in detail. We demonstrate that the failure model of boron carbide should be adjusted for compressions below 10 GPa to achieve a good agreement with our experimental images. Such an improved failure model provides the predictive simulation of long-term dynamics of targets after unloading, and it has almost no effect on wave profiles after plate impact.

Radiofrequency (RF) Mossbauer spectra in experiments on forward scattering by thick samples of iron borate (FeBO3) below the Neel temperature are measured. The spectra have satellites spaced by doubled RF-field frequency. A semiclassical model of Mossbauer transmission through a magnetic absorber exposed to RF reversals of a hyperfine field on nuclei is proposed. The model reproduces all features of the measured spectra. Experiments and modeling calculations indicate additional possibilities for studying soft magnetic materials using this measurement scheme.

The thermodynamic parameters—pressure and density—of quasi-isentropically compressed helium have been measured in a pressure range of 100–500 GPa. A thermodynamic model that satisfactorily describes the behavior of strongly compressed helium in a wide range of compression parameters has been proposed.

The quasi-isentropic compressibility of helium and deuterium plasmas at pressures of up to 1500–2000 GPa has been measured using devices with spherical geometry and an X-ray diagnostic complex comprising three betatrons and a multichannel imaging system with electro-optic gamma detectors. A deuterium density of 4.5 g/cm3 and a helium density of 3.8 g/cm3 have been obtained at pressures of 2210 and 1580 GPa, respectively. The internal energy of a deuterium plasma at the indicated pressure is about 1 MJ/cm3, which is about 100 times greater than the specific energy of condensed chemical explosives. Analysis of the obtained data shows that the degree of helium ionization under the achieved plasma compression parameters is about 0.9.

The quasi-isentropic compressibility of a helium plasma has been measured using a spherical experimental chamber, as well as an X-ray diffraction complex consisting of three betatrons and a multichannel optoelectronic system for the detection of X-ray images. The density of the compressed helium plasma of about 8 g/cm3 has been obtained in the experiment at a pressure of 5000 GPa. Analysis of the data indicates that helium at the measured parameters is in a single ionized state.

The transmission of Mossbauer radiation through a thick ferromagnetic crystal, exposed to a radio-frequency (rf) magnetic field, is studied. The quantum-mechanical dynamical scattering theory is developed, taking into account the periodical reversals of the magnetic field at the nuclei. The Mossbauer forward scattering (FS) spectra of the weak ferromagnet FeBO3 placed into rf field are measured. It is found that the coherent gamma wave in the crystal absorbs or emits only couples of the rf photons. As a result, the FS spectra consist of equidistant lines spaced by twice the frequency of the rf field in contrast to the absorption spectra.

Only one view of a picture is enough for a person to see strange defects, such as hairs, points, scratches, that, although small in size and contrast, stand out against the general scene. Large spots and stroke marks are also visible. In this paper a method of automatic detection of a wide range of point and extended defects in the pictures and correct determination of their dislocation areas is offered. The algorithm of quick median filtering by a large window and its modification removing the effect of prolonged constant fields at the output of a large median filter is described in the framework of solving the main task.

The approximate solution of a problem in image spatial transformations, as an example, rotations, is usually found with the use of one method or another of interpixel interpolation. In this case, integral characteristics of images are not retained, which makes difficulties for the further metrological processing of them. In the present article, an exact problem solution is proposed with the use of vector fields given analytically. The convolution of vector fields allows us to reduce the sequence of geometrical transformations to only the one that substantially decreases losses of spatial resolution for series of transformations and increases the transformation aperture.

The thermodynamic properties of a highly compressed deuterium plasma have been measured using an explosive spherical experimental chamber. The experiment has been performed with an X-ray diffraction complex consisting of three betatrons and a multichannel optoelectronic system of the detection of X-ray images of the process of the explosive spherical compression of deuterium. The density of the shock-compressed deuterium plasma ρ = (4.3 ± 0.7) g/cm3 at the pressure P = 1830 GPa has been detected at the initial pressure of gaseous deuterium P 0 = 267 atm and the temperature T 0 = 10.5°C. Under such conditions, the plasma is strongly nonideal (Γ ∼ 450) with the degenerate (nλ 3 ∼ 280) electron component and with an electron density of about 2.8 × 1023 cm−3.

The RF Mossbauer spectra have been measured on iron borate (FeBO3) in the forward scattering scheme. A model based on the mechanism of the RF reversal of the hyperfine field reproduces all features of the observed spectra, including the appearance of satellites at the double frequency.

Possible mechanisms for the partial transparency of a thin Mossbauer absorber under nuclear level anticrossing conditions were studied. The conditions leading to the most interesting transparency mechanism due to quantum interference were determined. The siderite (FeCO3) in which this effect was experimentally observed was considered.

In radiography, the quality of obtained images depends mainly on two factors, i.e., the dose absorbed by an object and the quantum efficiency of registration. Increasing the dose is extremely undesirable in medicine; in technical radiography, it constitutes a serious scientific and technical problem concerned with creation of a powerful X-ray apparatus. In connection with this, the problem of increasing the quantum efficiency of registration is highly urgent, most notably in technical radiography, where radiation with a hard spectrum is used and typical quantum efficiency sometimes amounts to only 1–2%. To achieve an effectiveness close to 100% (the ultimate quality of registration), it has been proposed to use, not a unit element, but rather several uniform or nonuniform elements, i.e., a packet, as a recorder.

Specific elementwise operations over images based on analyzing and synthesizing histograms are described. An image is seen as part of an essentially two-dimensional continuous function given on a discrete grid and normalized to an interval of [0; 1]. Images with degenerate histograms, i.e., images that include big continuous sections or a small number of quantization levels, are not considered. A histogram is a distribution of the image function, which is discrete in our case, with its sum (or area) normalized to 1. Such normalization makes operations invariant with respect to pixel size of the image and allows, with no loss of generality, changing sizes of the sampling grid (resampling) and adding uniformly distributed noise for ill-conditioned histograms.

A model of Mossbauer absorption in the nuclear level anticrossing regime with allowance for electron relaxation has been proposed. The role of quantum interference in the creation of particular transparency on Mossbauer transitions under these conditions has been determined and the dependence of this characteristic on the relaxation and mixing parameters has been obtained using the stochastic theory of Mossbauer relaxation spectra.

The measurement of the density of liquid argon at a pressure of about 1000 GPa in a cylindrical setup transforming shock compression to quasi-isentropic compression gives a value of about 9 g/cm3. The experimental data are compared with calculations. The results bring out clearly that no anomaly is observed in the behavior of isentropically compressed liquid argon at pressures up to about 1000 GPa.

A possibility of redistribution of line intensities in the spectrum of resonant Mossbauer scattering due to the RF-stimulated quantum interference of the spectroscopic amplitudes is shown. The three-level Σ scheme in the second order of the perturbation theory with respect to the interaction of γ radiation with nucleus is considered exactly taking into account the resonant RF field. The calculations suggest the use of the 57Fe isotope in magnetic materials in experiments.

The role of quantum interference (QI) in spectra of the resonant Mossbauer scattering is investigated. As a mechanism ensuring the QI conditions, the radio-frequency (RF) mixing of the spin sublevels of the excited nuclear state is considered. It is shown that QI leads to a significant intensity redistribution of the elastic and Raman scattering.

The role of quantum interference in the formation of the resonance scattering spectra of Mossbauer photons is studied. A resonant rf field mixing the spin levels of the excited state of a nucleus is considered to be the mechanism ensuring the conditions for quantum interference. A considerable intensity redistribution of the elastic and Raman scattering channels is shown to occur as a result of quantum interference.

A method is proposed for calculating the resonance fluorescence spectrum of coherent gamma radiation with a finite linewidth under conditions when the sublevels of the ground nuclear state are coupled through a strong field. The spectrum line shape is substantially affected by both the coherent effects induced in the system by a strong field and the finite gamma-radiation width. The results obtained earlier and in this work give impetus to experimental investigations into the coherence of a quantum system and quantum interference of Mossbauer gamma transitions through the excitation of coherent magnetization dynamics or an optical subsystem in solids.

A method is developed for calculating the resonance fluorescence spectrum of coherent radiation with a finite linewidth from a system whose energy levels are coupled through a strong field. In this case, the shape of the spectrum is essentially affected by quantum interference. The results obtained give impetus to investigations into quantum interference of Mossbauer gamma-radiative transitions in magnetic materials under conditions of induced coherent magnetization dynamics.

Results are presented of observations of artie cial optical effects in the atmosphere that were made mainly by means of all-sky cameras in northwest Russia and Scandinavia. There were six artie cial optical effects observed during 10 yearsof observations madesimultaneously from two or three stationsand e ve more from singlestations. Oneofthecaseswasregisteredbya televisioncameraonHeissIsland (Frantz-JosephLand ),andtheseobservations allowed assumptions to be made on the volumetrical shape of the phenomena. It was assumed to have a toruslike form rather than a spherical shape, and the luminosity was caused by Rayleigh scattering of sunlight by particles, which formed a gas and dust cloud during the launch of a rocket. Observations from distant points were used to maketriangulationmeasurements.Itwasshownthatalloftheobservedphenomenahad bothcommonand original features. The altitudes of luminosity for different cases varied from 230 to 1080 km. The clouds represented rapid horizontally expanding circular objects with the front edge propagation velocity of 3 ‐7 km¢ si 1. Diametrical sizes of luminousclouds in some casesexceeded 1600 km atlaterstages oftheirdevelopment. Fiveofthesix phenomena, the sizes of which were measured by triangulation, were most likely caused by launches from the Plesetsk rocket range in northwest Russia, whereas the remaining one apparently was launched from a place located in west of the Kazakh republic. The possibility of observations of such types of phenomena depends very much on sunlight conditions, direction of launch trajectory, and weather conditions.

The results of observations of the optical effects in the atmosphere, which were made mainly by means of all-sky cameras in northwest Russia and Scandinavia are presented in the paper. There were six of artificial optical effects observed during 10 years observations simultaneously from two or three stations. One of the cases was registered by a TV camera on Heiss Island (Franz-Joseph Land) and these observations allowed assumptions to be made on the volumetrical shape of the phenomena. It was assumed to have a torus-like form, and the luminosity was caused by Rayleigh scattering of sunlight by particles, which formed a gas and dust cloud during the launch of a rocket. Observations from distant points were used to make triangulation measurements. It was shown that the all observed phenomena had both common and original features. The altitudes of luminosity for different cases varied from 230 to 1040 km. The clouds represented rapid horizontally expanding circular objects with the front edge propagation velocity 3–7 km s−1. Diametrical sizes of luminous clouds in some cases exceeded 1600 km at later stages of their development. The possibility of observations of such type phenomena depends very much on sunlight conditions, direction of launch trajectory and weather conditions.

High-explosive driven generators of cylindrical and plane shock waves in ${\mathrm{D}}_{2}$ and ${\mathrm{H}}_{2}$ were used for the generation of warm and dense strongly nonideal matter with an intense interparticle interaction and Fermi statistics. Highly resolved flash x-ray diagnostics were used to measure the adiabatic plasma compressibility. The thermodynamic measurements demonstrated the 20% increase of density at megabar pressure, just in the density range, where the electrical measurements indicated a sharp---5 orders of magnitude---increase of electrical conductivity due to pressure ionization in strongly coupled plasmas.

In the three joint VNIIEF/LANL experiments RHSR-0,1,2 with a disk EMG and a three-layer liner system (Al-dielectric-Cu) a method of radial radiography was used to study growth of perturbations amplitude at the boundary between copper layer and polyethylene (in experiments RHSR-0,1) and water (in experiment RHSR-2); the growth occurs during the evolution of the Raleigh-Taylor instability of this boundary.

We studied the resonance fluorescence of Moessbauer radiation of Fe57 nuclei with coherently coupled nuclear sublevels. The obtained results prove that the traditional Moessbauer spectroscopy in scattering geometry is effective enough for experimental investigation of the quantum interference of gamma transitions and for studying the coherencies induced by external radiation fields.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Good longitudinal symmetry of magnetically driven metal cylindrical liners may be observed at a relatively short time of current rise, for example, in experiments at PEGASUS-2 facility. Because of interaction of the liner with current-conducting edge walls the symmetry of compression may be much worse in experiments with a longer rise time of current delivered by explosive magnetic generators (EMG). The present paper describes the results of study of near-wall effects negative influence on longitudinal symmetry of compression of liners, close in design to experiments at PEGASUS-2 facility, but at an order higher duration of current supplied by helical EMG. The work was conducted within the frames of liner technology program (LT-1 experiments).

Results of simultaneous TV observations of pulsating auroral patches and ELF-VLF-emissions in the morning sector carried out in Sodankylä (Finland) on February 15, 1991 are presented. Auroral pulsating activity was typical having pulsating patches with characteristic periods of about 7 s. Narrow-band hiss emissions and chorus elements at intervals of 0.3–0.4 s formed the main ELF-VLF activity in the frequency range 1.0–2.5 kHz at the same time. The analysis of auroral images with time resolution of 0.04 s allowed perfectly separate analysis of spatial and temporal variations in the auroral luminosity. Mutual correspondence between the behaviour of the luminous auroral patches and the appearance of ELF noise type hiss emissions and VLF chorus trains was found in two intervals chosen for analysis. While the hiss emissions were associated with the appearance of luminosity inside a limited area close to the zenith, the structured VLF emissions were accompanied by rapid motion of luminosity inside the area. The spatial dimension of the pulsating area was about 45–50 km and luminosity propagated inside it with velocity of about 10–12 kms. We discuss a new approach to explain the 5–15 s auroral pulsation based on the theory of flowing cyclotron maser and relaxation characteristics of ionosphere.Key words. Magnetospheric physics (auroral phenomena; magnetosphere-ionosphere interactions) · Space plasma physics (wave-particle interactions)

A model of Moessbauer absorption taking into account the effects of the electron relaxation and the nuclear levels anticrossing simultaneously has been proposed. The dependence of the absorption deficit (transparency) on the relaxation and mixing parameters has been obtained using the stochastic theory of Moessbauer relaxation spectra. The role of quantum interference in occurrence of a partial transparency on Moessbauer transitions has been explored under these conditions.

We analyzed long-term outcomes of the treatment of 217 patients (men - 126, women - 91), who underwent radical operations for stomach cancer in the period of 1972 till 1976. 14 patients were under 39, 52 - from 40 to 49, 50 to 59 - 52, 60 to 69 - 80, over 70 years old - 19. The youngest patient was 28 years old and the oldest - 76 years old. Most patients (185) were operated on at stage III of the disease, stage II was diagnosed in 27 patients, and stage IV - in 5 patients.