Pulsed Laser Deposition of Large‐Area Thin Films and Coatings

Simple and inexpensive methods of obtaining large‐area uniform in thickness and composition thin films on rotating substrates and moving ribbons through pulsed laser deposition have been proposed. Thin films of different compositions were prepared using these methods. The thickness uniformity of obtained films was preserved within the limits of ±3% on up to 300 mm diameter substrates. Also, a method of creating a laser spot with a certain configuration on the target is proposed allowing almost full utilization of the target material

Environmental aspects of post-operational bioremediation of the typical municipal solid waste landfill of the administrative district

The article deals with the environmental consequences o f testing the method o f biological remediation o f the closed typical municipal solid waste landfill of the administrative district. The essence o f the method consists in the introduction of adapted composites from aboriginal, adapted or modified biological systems, primarily microorganisms for catalysis o f the decomposition process o f the organic component of waste landfills and subsequent separation o f valuable recyclable materials. The article presents the results o f the impact assessment o f a typical solid municipal waste landfil

Thermoelectric Cooling at Cryogenic Temperatures

Experimental results demonstrating Peltier cooling below 10 K are reported, using crystals of the thermoelectric cerium hexaboride (CeB6). Direct measurements of the Peltier cooling showed δT up to ∼0.2 K in magnitude at T∼4–5 K. All three kinetic parameters: resistivity (ρ), heat conductivity (k), and Seebeck coefficient (S), characterizing the thermoelectric figure of merit ZT=S2T/ρk, were measured, giving high-confidence results

Laser-Powered Thermoelectric Generators Operating at Cryogenic Temperatures

A thermoelectric generator, operating in a cryostat at liquid helium temperatures, is described. Energy to the generator is supplied via an external laser beam. For this prototype device the associated heat load at permanent operation is comparable with the heat load associated with power delivery via metallic wires. Estimates indicate that still better performance can be enabled with existing thermoelectric materials, thereby far exceeding efficiency of traditional cryostat wiring. We used a prototype generator to produce electric power for measuring critical currents in Nb3Sn-films at 4K

Kinematic dynamo wave in the vicinity of the solar poles

We consider a dynamo wave in the solar convective shell for the kinematic $\alpha\omega$-dynamo model. The spectrum and eigenfunctions of the corresponding equations are derived analytically with the aid of the WKB method. Our main aim here is to investigate the dynamo wave behavior in the vicinity of the solar poles. Explicit expressions for the incident and reflected waves are obtained. The reflected wave is shown to be relatively weak in comparison to the incident wave. The phase shifts and the ratio of amplitudes of the two waves are found.Comment: 20 pages, 2 EPS figure

The mean tilt of sunspot bipolar regions: Theory, simulations and comparison with observations

A theory of the mean tilt of sunspot bipolar regions (the angle between a line connecting the leading and following sunspots and the solar equator) is developed. A mechanism of formation of the mean tilt is related to the effect of the Coriolis force on meso-scale motions of super-granular convection and large-scale meridional circulation. The balance between the Coriolis force and the Lorentz force (the magnetic tension) determines an additional contribution caused by the large-scale magnetic field to the mean tilt of the sunspot bipolar regions at low latitudes. The latitudinal dependence of the solar differential rotation affects the mean tilt, which can explain deviations from Joy’s law for the sunspot bipolar regions at high latitudes. The theoretical results obtained and the results from numerical simulations based on the nonlinear mean-field dynamo theory, which takes into account conservation of the total magnetic helicity and the budget equation for the evolution of the Wolf number density, are in agreement with observational data of the mean tilt of sunspot bipolar regions over individual solar cycles 15–24. © 2020 The Author(s).The work of KK and NS was supported in part by a grant from the Russian Science Foundation (grant RNF 18-12-00131) at the Crimean Astrophysical Observatory. AT would like to acknowledge support from RFBR grant 18-02-00098 for the observational data analysis. NK, KK, IR acknowledge the hospitality of NORDITA

Cross helicity and turbulent magnetic diffusivity in the solar convection zone

In a density-stratified turbulent medium the cross helicity is considered as a result of the interaction of the velocity fluctuations and a large-scale magnetic field. By means of a quasilinear theory and by numerical simulations we find the cross helicity and the mean vertical magnetic field anti-correlated. In the high-conductivity limit the ratio of the helicity and the mean magnetic field equals the ratio of the magnetic eddy diffusivity and the (known) density scale height. The result can be used to predict that the cross helicity at the solar surface exceeds the value of 1 Gauss km/s. Its sign is anti-correlated with that of the radial mean magnetic field. Alternatively, we can use our result to determine the value of the turbulent magnetic diffusivity from observations of the cross helicity.Comment: 9 pages, 2 figures, submitted to Solar Physic

Sensor Development for Single-Photon Thermoelectric Detectors

As we reported earlier [1], thermoelectric detectors can be competitive as nondispersive energy resolving focal-plane instruments in X-ray/UV spectrum. The first generations of prototype devices demonstrated the viability of detector design and provided good agreement between theoretical expectations and experimental data. These devices exploited sensors made of gold with a small fraction of iron impurity. To get the projected high resolution one needs another type of material, namely, lanthanum-cerium hexaborides. We report on the first experimental tests of the feasibility of lanthanum-cerium films as sensor materials. Progress with thin films of these materials argues for the success of these thermoelectric detectors