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

© Published under licence by IOP Publishing Ltd.The 2nd generation composite HTS tapes samples based on the GdBCO (123) compound were irradiated in a pulsed electron accelerator (Terek-2 facility, IOF RAS) through a tantalum target to determine the thermal and shock loads effect at the tantalum-HTS boundary on the HTS tapes superconducting characteristics. Scanning Hall magnetometry was used to characterize the HTS samples after the electron irradiation exposure. The thermal modes and shock load in a composite superconductor under the irradiation influence are estimated depending on the magnitude of energy contribution to the target. At a silver surface temperature equal to the melting temperature, the critical current value drops by 87% of the initial value. At lower energy, a weaker critical current decrease was observed. The temperature effects and shock waves roles under the irradiation is discussed.

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.

2019, Rudnev, I. A., Podlivaev, A. I., Osipov, M. A., Abin, D. A., Anishchenko, I. V., Pokrovskii, S. V., Руднев, Игорь Анатольевич, Подливаев, Алексей Игоревич, Осипов, Максим Андреевич, Абин, Дмитрий Александрович, Мартиросян, Ирина Валерьевна, Покровский, Сергей Владимирович

© 2019 Published under licence by IOP Publishing Ltd.Higherature superconducting tapes are very promising for application in rotary magnetic bearings owing to its excellent magnetic and transport properties as well as possibility to easy create magneto-levitation systems of various geometry. One of problem arising in the rotation superconducting bearings is the presence of the energy loss resulting from the magnetization hysteresis due to inhomogeneity of magnetic field from permanent magnets. In this report we present results theoretical studies of rotation losses in the model superconducting bearing based on commercial high temperature superconducting (HTS) tape. The bearing stator has a cylindrical shape and is made of a multilayer HTSC tape. The bearing rotor is made of permanent magnets located at the same radius relative to the axis of rotation. As a result of numerical calculations carried out in the framework of the critical state model, the rotor geometry was established, at which the value of energy losses was minimal.

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 work presents the complex results of the FEM H-formulation modeling of the thrust magnetic bearing based on 2G HTS tapes. The simulated bearing consists of the HTS stator and PMs rotor. In the model we have used the magnetic and transport characteristics of industrial GdBa2Cu3O7-x superconductors and also took into account the thermal properties of each layer of high-temperature superconducting tape and the features of the layered structure of the whole stack. The numerical simulation was performed using the finite element method. The developed model feature is a direct magnetic assembly rotation simulation. Load characteristics and losses in the system at several operating temperatures were obtained. Comparison with the experimental results was done.

2019, Pokrovskii, S, V., Mavritskii, O. B., Egorov, A. N., Mineev, N. A., Timofeev, A. A., Rudnev, I. A., Покровский, Сергей Владимирович, Маврицкий, Олег Борисович, Егоров, Андрей Николаевич, Тимофеев, Алексей Афанасьевич, Руднев, Игорь Анатольевич

We investigated the magnetic and transport characteristics of second generation high-temperature superconducting (HTS) tapes with an ordered array of antidots. We have performed modification of HTS GdBa2Cu3O7-delta industrial tape produced by SuperOx (Russia) using femtosecond laser exposure. We have created a local lattice of defects with the period 50 mu m and the size of every hole up to 1 mu m. We studied the dependence of the critical current on magnetic field and the angular dependence of the critical current. The influence of the array of artificial defects on the pinning force was shown in a wide range of magnetic fields. Transport and magnetization measurements reveal that these modifications of HTS tapes increases the trapped magnetic field and the critical current. The local increase in the critical current reaches 49%. These enhancements of the critical current have been observed in the intermediate angles. The proposed method of antidot arrays by laser drilling can be used for local modification of HTS tapes, and can improve the current-carrying characteristics of industrial tapes.

2019, Anishchenko, I. V., Pokrovskii, S. V., Rudnev, I. A., Osipov, M. A., Abin, D. A., Мартиросян, Ирина Валерьевна, Покровский, Сергей Владимирович, Руднев, Игорь Анатольевич, Осипов, Максим Андреевич, Абин, Дмитрий Александрович

© 2019 Published under licence by IOP Publishing Ltd.This paper presents a numerical layered 2G HTS tape model with the transport current flowing through it. The simulation is performed by using FEM H-formulation method implemented in the Comsol Multyphysics software. The model provides two cooling modes: cryocooler and liquid nitrogen. LN2 cooling mode provides for a complex hysteresis character of the liquid nitrogen boiling curve and the boiling regimes changing possibility between the stationary and the bubble boiling. The delay of the voltage rising with a transport current above the critical value pulse input is shown in the liquid nitrogen cooling case. The possibility of parameters calculating for current redistribution from the HTS to the stabilizing copper layer is shown, and the stabilizing coating thickness effect on the thermal transition critical current value is studied A comparison with experimental results is carried out.

2019, 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.In this work we present a computational model for a magnetic levitation system based on stacks of 12 mm x 12 mm second generation GdBa2Cu3O7-x high temperature superconducting (HTSC) tapes. In our model we have used the magnetic and transport characteristics of real industrial HTSC tapes. The thermal properties of each layer of high-temperature superconducting tape and the features of the layered structure of whole stack have also been taken into account. The numerical simulation was performed using the finite element method. Distributions of both magnetic field throughout the space and the current in every tape of the stack were calculated for two cases: (i) cryocooler cooling mode and (ii) cooling in the liquid nitrogen. The magnetization curves of the stacks in external field of a permanent NdFeB magnet and levitation force dependence on the gap between the magnet and the HTS tapes stack in these cooling modes were obtained. We have calculated heat transfer and temperature distribution in the system taking into account the effect of thermal properties of Hastelloy substrate, as well as Cu and Ag stabilization layers on the cooling process and dynamic magnetization. Simulation results were compared with the experimental data and a good agreement with numerical ones was shown.

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, 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 modelling of non-equilibrium states arising in high-temperature superconducting composites under current, magnetic, and combined control switching impacts types. The simulation and analysis of the dynamics of electrophysical and thermal processes occurring in the HTS composites layered structure taking into account the influence of local thermal processes in the composite structure, in particular, heat generation bursts during a pulse, has been performed. The HTS composite switching times from the superconducting to the normal state have been investigated for various current pulses amplitudes in homogeneous magnetic fields. An experimental verification of the numerical model has been carried out.

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.