Penetration of the magnetic field into the twinning plane in the type I and II superconductors

It is demonstrated that in the type I and II superconductors with low-transparent twinning planes (TP) the penetration of external parallel magnetic field into the region of the twinning plane can be energetically favorable. In the type I superconductors the twinning planes become similar to Josephson junctions and the magnetic field penetrates into the center of the TP in the form of soft Josephson-like vortices. This leads to increase in the critical magnetic field values. The corresponding phase diagram in the parameter plane "temperature - magnetic field" essentially differs from the one obtained without taking the finite value of the magnetic field near the TP into account. Comparison between obtained phase diagrams and experimental data for different type I superconductors can allow to estimate the value of the TP transparency, which is the only fitting parameter in our theory.Comment: 5 pages, 2 figure

Design features of new high-efficient steam-driven multistage ejector with external intercoolers

A range of design solutions for increasing the efficiency of multistage ejectors, applied in the steam turbine schemes, is developed. Following technical solutions are developed: vertical intercoolers with external U-tube bundles, multistage ejector elements configuration, possibility of the ejector performance optimizing by nozzle exit position changing. Suggested design solutions are successfully implemented in the ejector EPO-3-80, which is installed and is functioning at the Surgutskaya GRES-1 power plant.Для повышения эффективности работы применяемых в схемах паротурбинных установок, многоступенчатых эжекторов разработан ряд конструкторских решений. Разработаны следующие основные технические решения: вертикальные выносные промежуточные охладителей с U-образными трубками, компоновка элементов многоступенчатого эжектора, возможность оптимизации характеристики эжектора с помощью изменения расстояния между соплом и диффузором. Предложенные конструкторские решения применены и успешно апробированы в пароструйном эжекторе ЭПО-3-80, установленном и функционирующем на станции Сургутская ГРЭС-1

Location of the Energy Levels of the Rare-Earth Ion in BaF2 and CdF2

The location of the energy levels of rare-earth (RE) elements in the energy band diagram of BaF2 and CdF2 crystals is determined. The role of RE3+ and RE2+ ions in the capture of charge carriers, luminescence, and the formation of radiation defects is evaluated. It is shown that the substantial difference in the luminescence properties of BaF2:RE and CdF2:RE is associated with the location of the excited energy levels in the band diagram of the crystals

Theory and computation of covariant Lyapunov vectors

Lyapunov exponents are well-known characteristic numbers that describe growth rates of perturbations applied to a trajectory of a dynamical system in different state space directions. Covariant (or characteristic) Lyapunov vectors indicate these directions. Though the concept of these vectors has been known for a long time, they became practically computable only recently due to algorithms suggested by Ginelli et al. [Phys. Rev. Lett. 99, 2007, 130601] and by Wolfe and Samelson [Tellus 59A, 2007, 355]. In view of the great interest in covariant Lyapunov vectors and their wide range of potential applications, in this article we summarize the available information related to Lyapunov vectors and provide a detailed explanation of both the theoretical basics and numerical algorithms. We introduce the notion of adjoint covariant Lyapunov vectors. The angles between these vectors and the original covariant vectors are norm-independent and can be considered as characteristic numbers. Moreover, we present and study in detail an improved approach for computing covariant Lyapunov vectors. Also we describe, how one can test for hyperbolicity of chaotic dynamics without explicitly computing covariant vectors.Comment: 21 pages, 5 figure

Proton-induced activation cross sections in the energy range below 1 GeV

(Abridged) Modern studies and industrial applications related to the design, radiation protection, and reliability of nuclear facilities, medical applications, as well as space research and exploration are relying on extensive simulations and modeling. Computer codes realizing semi-classical and quantum molecular dynamics (QMD) approaches are often employed to make up for the lack of accelerator data on many nuclear reactions at intermediate and high energies (>10s of MeV/n) and are in high demand. This contribution focuses on the methodology of generating reliable proton-induced cross sections in the energy range below 1 GeV. We developed a problem-oriented computer framework based on MCNPX and CASCADE/INPE codes to calculate activation cross section data at intermediate and high energies. Goodness of the fits of nucleon-nucleus interaction models to the existing data is evaluated based on elaborated algorithms. The method is based on the analysis of a large set of data and calculated cross sections for different targets and residual nuclei in a wide range of proton energies using numerous criteria. In practice, this could be done by tuning the model parameters and algorithms to fit required experimental data subset, or through achieving unification and consistency of fundamental parameters for all considered reactions. The presented framework is pursuing the latter approach. We use proton-induced reactions on Si and Fe nuclei to illustrate the application of the developed multi-criteria algorithm, where we use all data below 1 GeV available from the EXFOR data library and the IAEA CRP "Benchmark of Spallation Models." We show that the analysis of the predictive power of various intermediate and high-energy models based on the multi-criteria algorithm allows more sophisticated selection of appropriate models in a given energy range and residual nuclei domain.Comment: A poster E1.16-0085-21 presented at an event E1.16 "Origin of Cosmic Rays," 43th COSPAR Scientific Assembly (hybrid), 28 Jan - 4 Feb 2021, Sydney, Australia. For a full agenda of the event E1.16, see https://www.cospar-assembly.org/admin/session_cospar.php?session=90

Test of the RF system for damping ring

RF system for VEPP-5 damping ring is described. The system consists of RF power supply, waveguide section, and 700 MHz cavity. Results of computer simulations and measurements of HOM spectrum and damping efficiency are presented together with the results of cavity testing at operating power level

RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam

The RF system is a part of the 1.6 - 2 MeV injector for the Race-Track Microtron - Recuperator (RTMR) that is under construction at BINP, Novosibirsk, for the Center of Photochemistry. RF system has three 180.4 MHz cavities. Buncher cavity operates at the accelerating voltage of 100 kV and two accelerating cavities operate at the gap voltage up to 800 kV. Cavities are driven by 3 power amplifiers. Maximum output power of amplifier which feeds the accelerating cavity is 130 kW. Low level electronics controls phase and amplitude of RF cavity gap voltages and generates signals for synchronization of the electron gun. Maximum current of injector (45 mA) is realized at 22.5 MHz repetition rate of electron bunches. The effects of beam – RF cavities interaction and the RF system operation results are presented