Low-density structured targets are widely used to study some isolated problems of ICF. Here we compare selected laser experiments with our targets, mostly non-thermonuclear, non-standard, ...individually designed for plasma features quantitative investigations. The mutual cross-check and verification is done in past few years, because "noizy" nature is more pronounced at less density. Our targets were applied on European drivers of LULI 2000, PALS, LIL, PHELIX, also on GEKKO-XII, in Russian-Indian laser-foam interaction series.
Cd
1 –
x
Zn
x
Te crystals are required for ionizing radiation detectors, which are widely used in science, technology, medicine, and other fields. Grown-in dislocations arise and low-angle boundaries ...form during crystal growth due to strains caused by crystallization. A typical problem of Cd–Zn–Te ternary compounds grown from melt are tellurium inclusions, which worsen the efficiency of detector operation. Microgravity conditions provide unique opportunities for the growth of high-quality crystals on account of the lack of convection, more equilibrium mixing of the melt, and a decrease in internal stresses. Since the properties of such crystals greatly depend on the production conditions, a seed and a feed ingot are needed with predetermined composition and structure. Ampoules with two compositions of the material have been prepared for space experiments. The crystals have been grown from loads with the compositions Cd
0.96
Zn
0.04
Te and Cd
0.9
Zn
0.1
Te, each consisting of an oriented seed, a solvent, and a feeding ingot. The latter are single-phase single crystals, with a chosen orientation and low dislocation density, which comply with the requirements for the growth of CZT crystals under microgravity conditions. The ampoules with the materials have been sent to the International Space Station (ISS) for CZT crystal growth using equipment for growth already installed on board the “Nauka” module.
We have used data from the space telescope SOHO/EIT and the spectrometer VEIS on the Wind spacecraft to compare the solar wind (SW) speed near Earth's orbit with changes in the area of polar coronal ...holes (CHs) on the Sun during the 1996 solar activity minimum. We have found that in March 1996 the SW speed correlated with the southern CH area by a factor of 0.64. In September and October 1996, a correlation was revealed between the SW speed and the area of the northern CH (the coefficients are 0.64 and 0.85 respectively). We believe that this confirms the assumption that the solar wind from polar CHs can penetrate into the ecliptic plane at solar minimum. The SW speed was 460–500 km/s, which is lower than that from equatorial CHs (600–700 km/s).
We report a numerical analysis of the stochastic acceleration of electrons, stipulated by a random change in the phase of the force acting on the electron. The main source of randomness is the random ...spatial distribution of electromagnetic fields in the focal region of multimode laser radiation. A typical frequency of the random phase change corresponding to the maximum impact of the effect under consideration lies in the range of (0.25 - 0.5)ν (ν is the radiation frequency of a neodymium laser). A wave packet model convenient for calculations taking into account the radiative transitions of the neodymium ion is proposed. The dependence of the average energy of relativistic electrons on the flux density in the range of 1015 - 1018 W cm−2 is calculated. The time dependence of the average electron energy during the laser pulse in the form of approximating formulas is constructed. The typical time for the development of stochastic heating of electrons is determined. It is found that the stochastic acceleration process weakly depends on the laser pulse duration, when the latter exceeds several hundred periods of the electromagnetic wave.
Victor Timofeevich Markov (21.06.1948–15.07.2019) Adrianov, N. M.; Artamonov, V. A.; Balaba, I. N. ...
Journal of mathematical sciences (New York, N.Y.),
04/2022, Letnik:
262, Številka:
5
Journal Article
Low-density targets continue to yield new experimental data and to put new unsolved questions for driver-plasma experiments. The experiments with such targets are presented in the paper by ..."Low-density targets that worked in direct and indirect experiments with laser and particle beams" by L.A. Borisenko et. al. ibid. Here we concentrate on nano structured and aerogel targets' fabrication and characterization. These configurations establish certain standards for contemporary shot experiments.
Production of density gradient aerogels with predetermined density steps or gradient is challenging, particularly when the experiments would demand a prescribed gradient in density along the axis of ...cylindrical shaped aerogel. In order to achieve this, it is vital to characterize and accurately measure the density gradient in order to “design” synthetic routes to achieve the desired density gradient that can be used in plasma physics experiments using high-energy lasers. X-ray tomography was used for the characterization of these aerogels and it is demonstrated that it is the most reliable and quick method for characterization of gradient density aerogels. Divinyl benzene aerogels samples were synthesized by Lewis acid catalysis and samples were supercritically dried, characterized and their parameters measured to realize that the necessary properties were achieved. The change in density from solid density to 100 mg/cm
3
is registered and the accuracy is evaluated.
The SDO/AIA 193 Å and ACE/SWEPAM data acquired in 2019 are used to compare the effects of polar and equatorial coronal holes (CHs) on solar wind (SW) characteristics under conditions of low solar ...activity. As expected, most geomagnetic storms in this period were caused by high-speed SW streams (
km s
) originating from equatorial CHs. At the same time, it has been shown that at a deep solar activity minimum polar CHs can exert a noticeable influence on SW characteristics at the Earth’s orbit. A correlation with a correlation coefficient of 0.8 has been found for the integrated polar CH area and the SW speed in the investigated period. The southern polar CH, for which a correlation with the SW speed with a correlation coefficient of 0.82 was found in the spring of 2019 (in the period when the south solar pole was maximally tilted to the Earth), exerted a particularly significant influence on the SW speed. The northern polar CH had virtually no effect on the SW speed. An anticorrelation of the polar CH area with the SW speed at the Earth’s orbit was found in the fall of 2019, in the period when the north solar pole was tilted to the Earth. We discuss a possible mechanism for the influence of polar CHs on SW characteristics and propose an interpretation of the results obtained.
The electronic structure and ionization processes of acetylacetonate and bromoacetylacetonate of boron difluoride were modeled using the method of outer valence Green's functions (OVGF). It was shown ...for boron difluoride acetylacetonate that for ionization energies exceeding 12 eV the OVGF method data (energies and a sequence of electronic levels, the electron density localization) differ significantly from the results of DFT calculations. Theoretical values of ionization energies from molecular orbitals with predominant contributions of atomic orbitals F 2p are higher by 1.6-2.2 eV than the corresponding Kohn-Sham energies shifted by the magnitude of the correction to the orbital energy. For all the considered electronic levels of both compounds, close theoretical values of the spectral intensities and good agreement between the results of calculations and the experimental data of the ultraviolet photoelectron spectroscopy method are observed.
Blood bacterial DNA is one of the pathogen-associated molecular patterns whose signaling pathways can alter the expression of neurotrophins, such as brain-derived neurotrophic factor (BDNF) and nerve ...growth factor (NGF). The study of neurotrophins is interesting in the context of obesity, which is associated with the risk of neuropathy. At the same time, the risk of complications depends on the metabolic type of obesity: in the metabolically unhealthy type (MUHO), this risk is significantly higher than in the metabolically healthy (MHO). The aim was to study the relationship between blood microbiome taxa and serum BDNF and NGF levels in different metabolic types of obesity. Healthy non-obese donors (
n
= 114) and obese patients (
n
= 98) were examined. Obese patients were divided into subgroups depending on the obesity metabolic type: patients with MHO (
n
= 36) and patients with MUHO (
n
= 53). Serum concentrations of neurotrophins were measured, and qualitative assessment of the blood microbiome was carried out by sequencing the variable region of the 16S rRNA gene. In healthy donors, taxa translocated from the skin and respiratory tract were negatively associated with BDNF, but in obesity, especially MUHO, this relationship was positive. Taxa translocated from the stomach (
Helicobacter pylori
) and intestine (
Sutterella
spp.) were negatively associated with BDNF in obese patients. NGF in healthy donors was positively associated with
Akkermansia muciniphila
, the taxon supporting intestinal integrity and reducing intestinal permeability. Patients with MUHO had a positive relationship between NGF and
Ruminococcus bromii
. Numerous negative relationships between the taxa of the intestinal flora and NGF were found in healthy donors and patients with MUHO, but not with MHO. In general, the effect of blood bacterial DNA on the serum concentration of neurotrophins depends on the translocation sources, permeability of the outer barriers, characteristics of microbiomes (gut, skin, etc.), as well as the presence or absence of metabolic disorders in patients with different body weight.
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