2019, Irina, Anischenko, Sergei, Pokrovskii, Igor, Rudnev, Osipov, Maxim, Мартиросян, Ирина Валерьевна, Покровский, Сергей Владимирович, Руднев, Игорь Анатольевич, Осипов, Максим Андреевич

In many levitation systems superconductors are used in combination with permanent magnets. In this paper we considered three types of magnetic assemblies that are most often used: with magnets oriented in one direction, oppositely oriented magnets and the Halbach array. Based on the H-formalism, we performed modeling of a magnetic field and levitation force in a system consisting of the high temperature superconductor (HTS) tape stack and the assembly of permanent magnets. It was shown that if a spatial distribution of a gradient magnetic field changes in height it is necessary to take into account the magnetic history of the superconductor. The proposed computational model includes a combination of scalar and vector potentials, as well as modeling the real movement of an HTS tape stack in a levitation system. The simulation results were verified by corresponding experiments. The proposed approach is universal for modeling levitation systems of complex configurations.

2019, Pokrovskii, S. V., Bura, A. A., Anishchenko, I. V., Rudnev, I. A., Покровский, Сергей Владимирович, Мартиросян, Ирина Валерьевна, Руднев, Игорь Анатольевич

© 2019, Pleiades Publishing, Ltd.This paper presents the results of studying the nonequilibrium processes in second generation HTS tapes under the action of pulsed current loads. In the study, we used short current pulses of various amplitudes from 0.9 to 5 values of the superconductor critical current. The minimum rise time of the current was 8 µs, and the pulse duration was from 1 to 250 µs. Comparisons in the behavior of samples under long current pulses with current rise time more than 3 ms were carried out. A qualitative difference in the formation of an nonequilibrium state during short and long current pulses was found. A stable current flow with amplitudes up to 4 times larger than the critical current was obtained without degradation of the superconductor. Experimental results were analyzed on the basis of the dynamic resistance model in the flux flow regime.

2020, Anishchenko, I. V., Pokrovskii, S. V., Rudnev, I. A., Мартиросян, Ирина Валерьевна, Покровский, Сергей Владимирович, Руднев, Игорь Анатольевич

© Published under licence by IOP Publishing Ltd.This paper presents the results of complex multiphysical modeling of nonequilibrium states arising in high-temperature superconducting composites under the pulsed current impact. The time dependences of the voltage on the superconducting tape under the influence of current pulses for the pulse amplitudes from 0.6 to 2 values of the critical current of the tape are obtained. Two linear modes of the sample voltage behavior during the electric current load are distinguished. A stable HTS sample switching at the current pulse amplitudes less than 1.7 Jc and the development of irreversible dynamic thermal instability for the higher currents are shown. The simulation was performed by the finite element method in the Comsol Multiphysics software package.

2019, Podlivaev, A. I., Pokrovskii, S. V., Anishchenko, I. V., Rudnev, I. A., Подливаев, Алексей Игоревич, Покровский, Сергей Владимирович, Мартиросян, Ирина Валерьевна, Руднев, Игорь Анатольевич

© 2019, Pleiades Publishing, Ltd. Abstract: A new technique for contactless magnetometric determination of the local critical current in high-temperature superconducting tapes is proposed. In contrast to conventional approaches, where currents in a superconductor are induced by a uniform magnetic field of an external source, in our variant the tape is magnetized by a series of bipolar permanent magnets. It is shown that, for solving a number of technical problems of defect diagnostics, the proposed approach is more effective than those used earlier. Two variants of diagnostics are discussed. The first variant is intended for express diagnostics of local defects (first of all, transverse cracks) in a separate tape and in a tape stack and the second variant is developed for the case of a smooth critical current variation in a separate tape. The proposed method can significantly improve the accuracy of determining the local critical current density.

2019, Podlivaev, A. I., Rudnev, I. A., Anishchenko, I. V., Подливаев, Алексей Игоревич, Руднев, Игорь Анатольевич, Мартиросян, Ирина Валерьевна

© 2019, Pleiades Publishing, Ltd.In the paper, the problem of magnetic drag and origination of energy losses in noncontact bearings based on high-temperature superconducting tapes is considered. The model configurations of bearings in which a superconducting tape is a stator and a set of permanent magnets is a rotor are investigated. It is shown that the magnetic friction can be neglected in the case where more than eight permanent magnets compose the rotor. This result indicates the possibility to create scaled magnetic bearings for the systems of long-term energy storage, for example, flywheel energy storage systems.

2019, Osipov, M., Starikovskii, A., Abin, D., Pokrovskii, S., Anischenko, I., Rudnev, I., Осипов, Максим Андреевич, Стариковский, Александр Сергеевич, Абин, Дмитрий Александрович, Покровский, Сергей Владимирович, Мартиросян, Ирина Валерьевна, Руднев, Игорь Анатольевич

© 2019 International Institute of Refrigeration. All rights reserved. In our report, we present new results on investigation of the influence of temperature on the levitation force between the stacks of high temperature superconducting tapes (or coated conductor - CC tapes) and a permanent magnets. We studied the changing in value of levitation force at decreasing of temperature down to 30 K for field cooled (FC) and zero field cooled (ZFC) modes for various number of tape in the stack. In the measurements we used 12 mm wide commercially available CC-tape manufactured by SuperOx. The tapes were cut into pieces 12 mm x 12 mm. The number of layers in the stack ranged from 5 to 100. Cooling of the CC-tapes stack was carried out in cryo-free cryostat. Temperature range was from 30 to 80 K. Results showed that temperature has much influence on levitation force in ZFC mode whereas for FC mode the influence of temperature on levitation force is insignificant. The experimental data were compared with the results of calculations performed by using COMSOL Multiphysics. The obtained results are very useful for the practical application in magnetic levitation based systems.

2019, Minaev, I. M., Troitskii, A. V., Ponomarev, A. V., Mikhailova, G. N., Anishchenko, I. V., Pokrovskii, S. V., Rudnev, I. A., Мартиросян, Ирина Валерьевна, Покровский, Сергей Владимирович, Руднев, Игорь Анатольевич

© 2019, Allerton Press, Inc.Samples of composite second-generation high-temperature superconducting (HTS) tapes based on the GdBCO (123) compound have been irradiated in a pulsed electron accelerator (system Terek-2, GPI RAS) through a tantalum target in order to determine how the thermal and shock loads arising on the tantalum-HTS interface affect the superconducting parameters of HTS tapes. Scanning Hall magnetometry was applied to characterize HTS samples subjected to electron irradiation. The thermal modes and shock load in a composite superconductor under irradiation are estimated as functions of the energy absorbed by the target. At a silver surface temperature equal to the melting point, the critical current decreases by 87% from the initial value. At lower irradiation energies, the decrease in the critical current is smaller. The role of the temperature effects and shock waves under this irradiation is discussed.