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    Comparing of the Magnetic Force Parameters of Superconducting Maglev System Using Horizontal and Vertical PMG Geometry in Multi-Surface HTS-PMG Arrangement
    (Springer, 2021) Ozturk, Kemal; Savaskan, Burcu; Abdioglu, Murat; Cansiz, Ahmet; Dilek, Durukan Burak; Karaahmet, Zekeriya
    In this study, a detailed static and dynamic experimental studies were carried out in different cooling heights (CH) by using two different multi-surface HTS-PMG arrangements with horizontal (MS-H) and vertical (MS-V) geometries to determine the optimum magnetic force, static stiffness, dynamic response, and dynamic stiffness parameters of superconducting Maglev system. The maximum levitation force values (in CH = 25 mm) were obtained as 202 N and 84 N, respectively, with horizontal and vertical geometry HTS-PMG arrangements, while the maximum guidance force values (in CH = 5 mm) were obtained as -58 N and -22 N, respectively. Also, the vertical static (in CH = 25 mm) and dynamic stiffness (in CH = 5 mm) values were determined as 33.8 N/mm and 37.8 N/mm, respectively, for MS-H and 12.3 N/mm and 25.1 N/mm, respectively, for MS-V arrangements. The bigger levitation force, guidance force, and both static and dynamic magnetic stiffness values of MS-H arrangement with horizontal geometry than that of MS-V arrangement with vertical geometry indicate that the horizontal HTS-PMG geometry is more suitable for practical Maglev applications in terms of loading capacity and movement stability.
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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.
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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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    Determination of magnetic levitation force properties of bulk MgB2 for different permanent magnetic guideways in different cooling heights
    (Elsevier Science Sa, 2020) Savaskan, Burcu; Abdioglu, Murat; Ozturk, Kemal
    In our study as different from the literature, the magnetic levitation force between a bulk MgB2 and two different permanent magnetic guideway (PMG) arrangements, which are Halbach and Conventional PMGs, were investigated in different cooling heights (CHs) and Field-Cooled (FC) condition at the temperatures of 37 K and 33 K. The cylindrical bulk MgB2 superconductor was fabricated by in-situ solid state reaction process with the diameter of 18 mm and the height of 5 mm. The XRD data indicates well developed MgB2 phase and the Jc value was obtained as 68 kA/cm(2) at 30 K in the self-field. Experimental results show that MgB2 bulk above the Halbach PMG can exhibit better load capability at all the cooling heights between the bulk MgB2 and the PMG due to a more suitable magnetic field distribution. The maximum levitation force for Halbach PMG corresponds to 16.86 N whereas the conventional PMG shows 9.02 N at 37 K in cooling height of 77 mm. Additionally, the maximum levitation force increases while the CH increases because flux exclusion is more effective for larger CHs. It is considered that the experimental results obtained in study are very useful for future Maglev applications, because there are limited number of studies on magnetic levitation force of MgB2 bulk for different MgB2-PMG arrangements. (c) 2020 Elsevier B.V. All rights reserved.
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    Experimental and Numerical Investigation of Levitation Force Parameters of Novel Multisurface Halbach HTS-PMG Arrangement for Superconducting Maglev System
    (IEEE-Inst Electrical Electronics Engineers Inc, 2021) Ozturk, Kemal; Badia-Majos, Antonio; Abdioglu, Murat; Dilek, Durukan Burak; Gedikli, Hasan
    We have designed multisurface Halbach high temperature superconductor-permanent magnetic guideway (HTS-PMG) arrangements for magnetically levitated transportation (Maglev) and investigated the static force parameters in addition to the dynamic response characteristics. Three different Halbach HTS-PMG arrangements were used with multisurface (6 HTS, 4 HTS) and single surface (2 HTS) configurations and static and dynamic measurements were carried out in three different field cooling heights (FCHs). The bigger vertical loading capacity and wider loading gap were obtained with multisurface Halbach HTS-PMG arrangements. In addition, nearly four times bigger guidance force values of multisurface arrangements than that of single surface one indicates that the side HTSs in multisurface arrangements make a significant contribution to the guidance force and thus lateral movement stability ofMaglev systems. Both the vertical and lateral dynamic stiffness values increased with decreasing FCH and it can be also said that the dynamic stiffness properties of Maglev systems can be enhanced especially in lateral direction by using the multisurface Halbach HTS-PMG arrangements. Understanding of these experimental observations is supported by dedicated theoretical modelling through a 2-D approximation of the system. We show that by using a single material parameter (the critical current density J(c)) for the whole superconducting set, one may satisfactorily predict the complete series of experiments. The static and dynamic parameters obtained from this study and the results of dedicated theoretical modeling for single-surface and multisurface HTS-PMG arrangements are thought to be helpful for the researchers working on static and dynamic performances of HTS Maglev systems.
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    Frozen image analysis of a superconducting magnetic levitation system consisting of multi-surface superconductor and Halbach array permanent magnet configuration
    (Elsevier Sci Ltd, 2021) Cansiz, Ahmet; Reisoglu, Ahmet F.; Ozturk, Kemal; Abdioglu, Murat
    Levitation strength provided by high temperature superconductors are limited for device applications. Although superconducting material properties are continuously improving, there is still strong necessity of efficient design mechanisms for the superconducting magnetic levitation systems. Studies in the last decades have shown that combining multi-surface superconductor and permanent magnet components in optimum configurations has improved the levitation forces. In this respect, Halbach arraying permanent magnets interacting with multisurface superconductors has become one of the most utilized methods. This paper investigates frozen image modeling of the levitation and guidance forces on a particular levitation system, which consists of a permanent magnet guideway and high temperature superconductor car body. The levitation enhancement is investigated for three configurations according to force interactions between the guideway and car body. These configurations are based on the use of single permanent magnet-single superconductor, Halbach array permanent magnetssingle superconductor and Halbach array permanent magnets-multi-surface superconductors. The vertical and guidance forces for the present configurations were calculated in terms of field cooling and zero field cooling conditions by using frozen image model with magnetic dipole approximation. The predicted force calculations are analyzed in terms of vertical and lateral traverses of the car body respect to guideway for particular measurement distances. The force analysis provided by frozen image model qualitatively agree with the previously obtained experimental data.
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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.