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    Design and Experimental Studies on Superconducting Maglev Systems With Multisurface HTS-PMG Arrangements
    (Ieee-Inst Electrical Electronics Engineers Inc, 2021) Abdioglu, Murat; Ozturk, Kemal; Ekici, Mehmet; Savaskan, Burcu; Celik, Sukru; Cansiz, Ahmet
    In this article, we have designed and constructed a new multisurface (MS) high temperature superconductor (HTS) Maglev measurement system to investigate the enhancement of magnetic force properties of Maglev systems via MS HTS configurations above conventional permanent magnetic guideway (PMG). We have investigated both the static force and stiffness behavior and dynamic response characteristics of these MS HTS-PMG arrangements in different field cooling heights (FCHs). Optimum cooling height is determined as FCH 20-30 for both six- and four-HTS configurations. The maximum levitation force values of HTS-PMG arrangement with six-HTS were obtained bigger than that of four-HTS in the unit cryostat volume of MS arrangement, indicating that the HTSs at the bottom side of the cryostat make contribution to the loading capacity of Maglev systems. In the present article, it is observed that the magnetic flux density of bottom surface in addition to upper surface of the PMG can make a contribution to loading performance, vertical and lateral stability of Maglev systems. It is thought that the designed measurement facility and results of this study will be beneficial to increase the magnetic flux density in the unit volume via MS HTS-PMG arrangements for future design and construction of the HTS Maglev systems.
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    Enhanced Magnetic Levitation and Guidance Force in MgB2 Bulks by Synthetic Engine Oil Immersion
    (Springer, 2019) Savaskan, Burcu; Koparan, Ezgi Taylan; Guner, Sait Baris; Ozturk, Kemal; Celik, Sukru
    We have used Synthetic engine oil' as a rich easily accessible carbon source and investigated the effect of engine oil on the microstructure, critical current density (J(c)), vertical levitation force (F-z) and guidance force (F-x) properties of MgB2 superconductor. The polycrystalline disk-shaped MgB2 bulk samples have been prepared using two-step solid-state reaction process. After the first heating process, MgB2 bulk samples immersed in the engine oil for different durations (30, 120, 300 and 1440 min). XRD analysis indicated the decreasing of lattice parameters of samples and confirmed C substitution in boron sites. Vertical levitation and guidance force measurements were carried out with both Field-cooling (FC) and zero-field-cooling (ZFC) regimes at different temperatures of 20, 24 and 28 K. It was found that engine oil addition slightly increases the levitation and guidance force properties. The Fz values were obtained as 11.17 and 11.58 N for pure and MgB2 sample immersed for 30 min at 20 K in ZFC regime. In addition, the MgB2 sample immersed for 300 min in engine oil showed the highest Jc value of 5.3x104 A cm(-2) at 15 K and self-field and showed the highest guidance force value of 4.14 N at 20 K. These finding suggest that synthetic engine oil is a cost-effective and promising method to improve the levitation and guidance force performance as well as the critical current density of MgB2 bulk superconductor.
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    Investigation on superconducting and magnetic levitation force behaviour of excess Mg doped-bulk MgB2 superconductors
    (Elsevier Sci Ltd, 2019) Guner, Sait Barb; Savaskan, Burcu; Ozturk, Kemal; Celik, Sukru; Aksoy, Canan; Karaboga, Firat; Koparan, Ezgi Taylan
    A series bulk samples of MgB2 + x wt% of Mg (x = 0, 5, 10, 15, 20 and 30) were fabricated by solid state reaction method. The structural and electromagnetic properties of MgB2 samples were studied using X-ray diffraction (XRD), scanning electronic microscope (SEM), electrical resistivity (R-T), magnetic hysteresis (M-H), magnetic levitation (F-z) force and lateral force (F-x) measurements. The maximum repulsive and attractive force values of 15 wt% of excess magnesium MgB2 sample compared to the other samples imply that the intergranular connection between grains enhanced while pore and microcrack density decreased which brings an increase in the values of the radius of a shielding current loop (r) and the critical current density (J(c)). It was determined that to obtain the enhancement of the micro and macro structure properties, causing to the higher critical current density, and the maximum levitation and lateral force values, the optimum excess magnesium content was 15 wt % into sample. It is thought that an addition of 10-15% excess magnesium can be tried for spark plasma or other methods -as a further research- and the results showed a potential to guide the researchers to study on the material-fabrication and the magnetic bearing system.
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    Lateral Force Measurements for (Gd123)1-x :(Gd211) x Superconductors at Different Temperatures
    (Springer, 2017) Guner, Sait Baris; Celik, Sukru; Cansiz, Ahmet; Ozturk, Kemal
    The lateral levitation force between melt-textured (Gd123)(1-x) :(Gd211) (x) bulk superconductors for x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5 and a permanent magnet is measured at 30, 40, 50, 60, and 77 K under zero-field-cooling and field-cooling conditions. The variations on the observed levitation force are correlated to the varied content of Gd211 in these melt-textured samples.
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    Magnetic levitation force and trapped field properties of multiseeded YBCO with triangular arrangement of seeds
    (Wiley, 2022) Abdioglu, Murat; Guner, Sait Baris; Ozturk, Kemal; Yang, Chiaming; Chen, Ingann; Celik, Sukru
    Although there are studies in literature using different number of seeds with different arrangements, especially line and rectangular, it is seen that there is no detailed study handling the levitation force together with trapped field properties of triangular arrangement of seed in YBCO. Therefore, to further investigate the magnetic properties of seeded YBCO superconductors, we have fabricated cylindrical YBCO (YBa2Cu3O7) superconductors with triangular arrangement of the seeds with different seed distances. Maximum levitation force values were obtained as 39.4 N and 57.1 N, while the maximum guidance force values were obtained as -4.6 N, and -8.7 N, respectively, with single-seeded and triangular-seeded samples with seed distance of 14 mm. It was determined that the trapped field, levitation force, and guidance force firstly decreased from the single-seeded sample to the triangular-seeded sample with small seed distance and then increased with increasing seed distance. Increased field trapping and levitation force performances in the triangular-seeded samples with suitable seed distance indicate that the triangular arrangement of seeds is an eligible method to produce larger dimension YBCO samples with bigger shielding current radius and bigger averaged trapped field values.
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    The comparison of levitation and lateral force of bulk and cut-pasted bulk GdBCO samples at different temperatures
    (Elsevier Science Sa, 2020) Guner, Sait Baris; Abdioglu, Murat; Ozturk, Kemal; Celik, Sukru
    In this work, in the first time, we have investigated the levitation and lateral force properties of bulk and cut-pasted bulk GdBCO samples at different temperatures and different cooling heights (CH) to determine the effect of cut-pasted process on the magnetic levitation force behaviour. The measurements of superconducting characteristics indicated that the attractive and repulsive force values of cut-pasted GdBCO sample are slightly lesser than those of GdBCO bulk sample. The maximum repulsive and attractive force values obtained as 15.45 N and -4.56 N for GdBCO bulk and as 14.78 N and -3.92 N for cut-pasted GdBCO samples at 37 K. Although there are many fabrication methods as melt-textured growth (MTG), top seeded infiltration growth (TSIG) and TSMG to produce large HTS samples, the desired large sample size and the sample shape compatible with the superconducting magnetic bearing systems are not still sufficient for the technological applications. In this study, the performed cut-pasted process and obtained magnetic levitation force data can be using for the increment sample size and the desired sample shape in the needed different geometry and size for superconducting magnetic bearing systems. (C) 2020 Elsevier B.V. All rights reserved.