The fusion power density produced in a tokamak is proportional to its magnetic field strength to the fourth power. Second-generation high temperature superconductor (2G HTS) wires demonstrate ...remarkable engineering current density (averaged over the full wire), JE, at very high magnetic fields, driving progress in fusion and other applications. The key challenge for HTS wires has been to offer an acceptable combination of high and consistent superconducting performance in high magnetic fields, high volume supply, and low price. Here we report a very high and reproducible JE in practical HTS wires based on a simple YBa2Cu3O7 (YBCO) superconductor formulation with Y2O3 nanoparticles, which have been delivered in just nine months to a commercial fusion customer in the largest-volume order the HTS industry has seen to date. We demonstrate a novel YBCO superconductor formulation without the c-axis correlated nano-columnar defects that are widely believed to be prerequisite for high in-field performance. The simplicity of this new formulation allows robust and scalable manufacturing, providing, for the first time, large volumes of consistently high performance wire, and the economies of scale necessary to lower HTS wire prices to a level acceptable for fusion and ultimately for the widespread commercial adoption of HTS.
We have obtained a solution of the Ogorodnikov–Milne stellar-kinematics equations based on the material of the entire Gaia EDR3 star catalogue containing 1.8 billion objects. In view of the ...insufficient accuracy of individual trigonometric parallaxes, we have also obtained an analogous solution based on a sub-catalogue of selected 98 million stars for which the parallaxes are known with an accuracy better than 1
. We have performed a detailed analysis of these solutions as a function of stellar magnitude and distance.
This study is devoted to intrinsic nonlinear distortions of induction sensors. The case where these distortions are of magnetoresistive nature is considered. It is revealed that such distortions ...prevail in the temperature range below 20–30 K. It is shown that such a mechanism can lead to the appearance of both even and odd harmonics. In this case, the presence of any spectral components will be controlled by the external dc magnetic field and excitation current amplitude.
Keywords:
induction sensor
contactless technique
nonlinear response
In a recent issue of the journal Herald of the RAS (No. 1, 2021), the article “Achievements of Space Astrometry” discussed the development of astrometry from ancient times to the Gaia space project. ...In this work, continuing this topic, the properties of the latest release of the Gaia EDR3 stellar catalog, containing 1.8 billion objects, are analyzed in detail. Methods of processing its data on personal computers accessible to most users are discussed. A detailed statistical study of the catalog was carried out, and the distribution of stars in the celestial sphere was obtained, making it possible to assess the volume and quality of the material. The analysis of the three-band photometry of the catalog is made, and the distributions of color indices and the Hertzsprung–Russell diagram are plotted.
This paper is devoted to the study of one of the causes of the appearance of intrinsic nonlinear distortions of induction sensors. It is revealed that the induction sensor coil sometimes is itself a ...source of nonlinear excitation signal distortions, preferentially at the 3rd harmonic frequency. It is shown that the appearance of intrinsic nonlinear distortions of the induction sensor can be associated with the temperature oscillation caused by current flows and dominates at liquid-nitrogen temperatures.
Abstract
The results of numerical modeling of the stress-strain state of the geomassif under the influence of natural technogenic forces are presented. To carry out computational experiments, a ...mathematical model was developed, in the constitutive relations of which the nonlinear relationship between stresses and deformations of rocks and their different resistance to tension or compression are taken into account. A computer program was developed, and an example is given in which the results of a nonlinear solution and a boundary value problem of the theory of elasticity are compared.
A 250 GHz continuous-wave (CW) gyrotron has been developed at the IAP RAS jointly with GYCOM Ltd., as a prototype of the microwave source for the envisaged prospective nuclear fusion power plants ...(DEMO). The main applications of such a tube are electron cyclotron resonance heating and electron cyclotron resonance current drive of magnetically confined plasma as well as its diagnostics based on collective Thomson scattering in various reactors for controlled thermonuclear fusion (e.g., tokamaks and stellarators). The results of the preliminary experimental tests in a pulsed mode of operation are presented. The microwave power of up to 330 kW with an efficiency of 30% without collector depression was obtained. At an accelerating voltage of 55 kV and an electron beam current of 12.5 A (which corresponds to the design parameters for CW operation), the measured output power was about 200 kW. The TEM
mode content evaluated at the tube output is not less than 98.6%.
Achievements of Space Astrometry Tsvetkov, A. S.
Herald of the Russian Academy of Sciences,
2021/1, Volume:
91, Issue:
1
Journal Article
Astrometry is the basis for astronomical observations and measurements of coordinates and time. Its main task is to implement a reference frame—the one mentioned in Newton’s first law. Since ancient ...times, astronomers have created star catalogs for this purpose. Work on them led to the discovery of the precession and nutation of the Earth’s axis, proper motions and parallaxes of stars, and the orbital motion of binary stars. The modern International Celestial Reference Frame (ICRF) is based on observations in the radio and optical range of very distant objects—quasars. It is to them that the GPS or GLONASS system is tied in the navigation device. The 21st century, with its computational capabilities, has led to the creation of star catalogs of unprecedented power, containing over a billion objects. However, the main breakthrough, even a revolution in astrometry, has happened in space observations. Two spacecraft have already created star catalogs of fantastic accuracy, which makes it possible to approach the solution of problems even the setting of which was unthinkable a few years ago. This article is dedicated to an overview of the achievements of astrometry over the past two millennia, massive star catalogs, and space astrometric projects.
We have solved the Ogorodnikov–Milne stellar-kinematics equations in the Galactic rectangular coordinate system based on the total velocities for a special sample of stars with radial velocities from ...the final Gaia Data Release 3 catalogue. We have found the region of applicability of the linear model and the regions that it describes poorly. We have constructed a second-order model that takes into account the peculiarities of stellar kinematics more accurately and showed its applicability for stars at distances up to 5 kpc.
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