Savaskan, B.; Ozturk, U. K.; Guner, S. B.; Abdioglu, M.; Bahadir, M. V.; Acar, S.; Somer, M.; Ionescu, A. M.; Locovei, C.; Enculescu, M.

Bulk MgB2 discs were prepared by an in situ route from mixtures of magnesium and boron powders. The boron powders were produced by two methods. The first one consisted of a self-propagating high tem-perature magnesiothermic synthesis (SHS) process followed by acid and fluorine cleaning and a heat treatment in inert atmosphere. This approach produced boron with purities between 86 % and 97 %, where the main impurity was Mg. Depending on the final heat treatment, these boron powders were amorphous or crystalline. In the second route, high purity nano powders (99 %) of boron were obtained by a diborane pyrolysis process. Bulks of MgB2 were characterized by structural, microstructural, and magnetic mea-surements. Critical current density, pinning force aspects and levitation force (including guiding force) details were assessed. Amorphous lower purity boron (86-97 %) obtained by the first processing route was found to promote the largest levitation forces of the MgB2 bulks and, among these samples, the best le-vitation results were recorded when using boron with a purity of 95-97 %. Use of a lower purity boron that decreases the cost of MgB2 promotes large scale production at industrial level of bulk MgB2 super-conducting magnets for levitation applications and enhances the applicability potential of MgB2 super-conductor. The relationship between levitation force and specific features of the samples such as pinning force details are discussed.& COPY; 2023 Elsevier B.V. All rights reserved.

AtıfScopus10·WoS10·OpenAlex12

İncele

Ozturk, K.; Abdioglu, M.; Karaahmet, Z.

We have designed a multi–surface HTS (high temperature superconductor with three seeded bulk YBaCuO) Maglev system by increasing the YBaCuO number while decreasing the PM number in HTS–PMG system to enhance the loading capacity and stability of the superconducting Maglev system while reducing the fabrication cost. By this study, a detailed investigation on the magnetic levitation force, guidance force, magnetic stiffness and cost analysis of the multi–surface HTS Maglev system has been carried out for the first time. In this study, it is determined that the multi–surface YBaCuO–PMG arrangements are superior to the single–surface arrangements with respect to the loading capacity and especially the movement stability of Maglev systems together. Additionally, it is seen that the using of the multi–surface YBaCuO–PMG arrangement reduces the fabrication cost of the Maglev systems as 42.0% for 1000 km magnetic rail while increasing of the levitation force efficiency as 43.4% and this emphasizes the advantage of multi–surface arrangements to the classical single–surface ones. The obtained results can contribute to the researchers working on Maglev and have a capability to increase the usage potential of Maglev systems in commercial applications because of both the loading capacity and stability of Maglev systems can be enhanced together with reducing the fabrication cost without any loss in levitation performance.

AtıfScopus19·WoS18·OpenAlex21

İncele

Ozturk, K.; Guner, S.B.; Abdioglu, M.; Demirci, M.; Celik, S.; Cansiz, A.

The higher magnetic levitation force and related stiffness values are very important for Maglev and magnetic bearing applications. Also, larger superconducting surface area is needed for continuous and larger magnetic mediums with different geometries and dimensions in real scale industrial applications of superconducting systems. In this study, the cylindrical YBCO superconductors were fabricated by top−seeded melt growth (TSMG) method in single and two−seeded forms with different seed distances and then the magnetic force and stiffness measurements were carried out by three axes magnetic force measurement system in different cooling heights (CH) of 20 mm and 75 mm. Additionally, a new analytical method, based on the magnetic dipole approximation, is proposed to calculate the levitation force in this study, named as Modified Advanced Frozen Image Method (MAFI), since although the Advanced Frozen Image Method in literature can calculate the levitation force with hysteresis, this method does not include the size effect of the superconductor. In the experimental studies, it is seen that the maximum levitation force values obtained by PMG with three PMs (named PMG−1) are more than two times higher than that of obtained with single PM for all samples with different distance of seeds, because of the higher magnetic flux distribution of related PMG arrangement than the single PM. In addition, the maximum magnetic levitation force value firstly increased and then decreased due to current coupling effect weakness by increasing distance of seeds. The calculated analytical levitation force results are not compatible with the experimental results without current coupling effect, but a well agreement is observed when the current coupling effect is taken into account in calculations. Also the MAFI method was tested with different dimensions of superconductors and the obtained results indicated the success of the proposed method. The maximum levitation force values obtained with MAFI method increased with increasing dimensions of HTS and PMs. Thus, one can say that the MAFI method is useful for the levitation force calculations between multi−seeded superconductors and PMGs with different dimensions and for different CHs. As a result, the analytical levitation force values obtained with the MAFI method are agree with the experimental levitation force sufficiently and this method can give fast calculation results without any divergence problem. This method can be thought as an alternative to the numerical calculation methods, having serious divergence problems for much amount and bigger size superconducting samples, therefore it will be useful to clarify bulk superconducting properties as supporter to the experimental studies.

AtıfScopus19·WoS18·OpenAlex22

İncele

Abdioglu, M.; Ozturk, K.; Guner, S.B.; Celik, S.; Kucukomeroglu, T.

The magnetic levitation force in vertical direction and guidance force in lateral direction should be increased for enhancing the loading capacity and stability of Maglev systems, respectively. In this study, we have produced multi‒seeded YBCO (YBa2Cu3O7) superconductors with two seeds and investigated the effect of seed distance on the vertical levitation force and lateral guidance force properties by using different permanent magnetic guideway (PMG) arrangements. Although there are studies in literature related to different distance, orientation and angle of seeds; there is no detailed study investigating the effect of seed distance on the vertical and lateral magnetic force properties of Maglev systems depending on different types of PMGs. In this study, after the sample fabrication, the optimum PMG arrangement were determined by using numerical simulation to obtain magnetic flux density distribution. It is determined that both maximum levitation and guidance force values firstly increased with increasing the seed distance from 0 to 4 mm and then related forces decreased with increasing the seed distance from 4 to 16 mm but still keep the higher force values than the sample with the seed distances of 0 mm. This situation is clarified as the increasing of the seed distance to an optimum value enhances both the levitation and guidance forces simultaneously and this is very important for levitation force applications because it causes to easy control of the Maglev system in vertical and lateral directions.

AtıfScopus4·WoS4·OpenAlex5

İncele

Abdioglu, M.; Ozturk, K.; Kabaer, M.; Ekici, M.

The stable levitation and guidance forces at higher force levels are important parameters for technological applicability of high temperature superconductors (HTSs) in Maglev and Flywheel energy storage systems. In this study, we have investigated the levitation and guidance force relaxation of both the single-seeded and multi-seeded YBCOs for different (HTS)−permanent magnetic guideway (PMG) arrangements in different cooling heights (CH). The measured saturated force values of Halbach PMG arrangements are bigger than the maximum force values of other PMGs. It is determined that the normalized magnetic levitation force (MLF) and normalized guidance force (GF) relaxation rate values decrease while the relaxation rates increase with increasing magnetic pole number and the effective external magnetic field area for both the single−seeded and multi−seeded YBCO. Also it can be said that the force stability at the higher force value of Halbach PMG arrangement indicates that the relaxation quality of Halbach PMG is better than that of the others. Additionally, it can be said that both the MLF and GF relaxation qualities of the multi−seeded YBCOs are better than that of the single−seeded ones. This magnetic force and relaxation results of the single−seeded and multi−seeded YBCOs are useful to optimize the loading capacity and lateral reliability of HTS Maglev and similar magnetic bearing systems.

AtıfScopus5·WoS5·OpenAlex6

İncele

Abdioglu, M.; Kabaer, M.; Ozturk, K.; Erdem, O.; Celik, S.

The magnetic levitation force (MLF) and the guidance force (GF) should be improved for loading capacity and stability of Maglev systems, respectively. Although there are some ways to increase these properties, using of auxiliary onboard permanent magnets (PMs) can be considered as the most efficient one. The auxiliary PMs increase the MLF significantly but, at the same time, decrease the GF. We have searched a solution to overcome this problem in this study. Firstly, we have determined the optimum vertical positions of the auxiliary PMs and then we have investigated the vertical levitation force and lateral guidance force of hybrid Maglev system depending on lateral position of auxiliary PMs in different cooling heights (CHs). A cylindrical YBCO superconductor, fabricated by a top seeding method with the diameter of 45 mm and the height of 15 mm, was used as a high-temperature superconductor (HTS). The maximum increment rate in MLF and the minimum decrement rate in GF were observed as 277 and 54 %, respectively. The increment in MLF was obtained five times more than the decrement in GF, and this reality points out that the results of this study can be useful for improving the loading capacity and thus enhancing the practical applicability of Maglev systems.

AtıfScopus16·WoS14·OpenAlex14

İncele

Erdem, O.; Abdioglu, M.; Guner, S.B.; Celik, S.; Kucukomeroglu, T.

The effect of coronene (C24H12) addition on the levitation force properties of MgB2 superconductor has been investigated for the first time in this study. The polycrystalline disk-shaped MgB2 + y wt % C24H12 samples (y = 0, 2, 4, 6, 8, 10), were synthesized by a pellet/closed tube method at 850 °C under Ar atmosphere, after hot pressing at 200 °C. XRD analysis indicates a decrease in lattice parameters of coronene added samples and confirms substitution of carbon in boron sites. An increase in lattice strain and a decrease in grain size are observed due to the carbon substitution effect. Vertical and lateral levitation force measurements under zero-field-cooled and field-cooled regimes were carried out at different temperatures of 20, 25 and 30 K. It was found that the coronene addition significantly increases the high-field critical current density of MgB2. The Jc values were obtained as 4.6 × 103 Acm−2 and 1.3 × 104 Acm−2 for pure and 4 wt % coronene added samples at 20 K and 4 T. In addition, the levitation force measurements show that 4 wt % coronene adding is very effective in increasing both the vertical and lateral levitation force performances at 20 K. The maximum levitation force for 4 wt % coronene added sample corresponds to 7.58 N/g whereas the reference sample shows 6.73 N/g at 20 K in ZFC regime. The results point out that the hydrocarbon of C24H12 is an effective carbon-containing additive for MgB2 and can be useful for optimizing the levitation performance of MgB2 superconductors for potential applications.

AtıfScopus25·WoS21·OpenAlex27

İncele

Ozturk, K.; Kabaer, M.; Abdioglu, M.; Patel, A.; Cansiz, A.

In our study as different from the literature, which are mostly related to superconductor fabrication, application and optimization, especially physical origins of bulk supercurrent generation, magnetic levitation and stability properties of the multi-seeded YBCO superconductor are investigated in point of supercurrent coupling effect. Besides the experimental measurements, a simplified simulation of the supercurrent coupling in the multi-seeded bulk YBCO is carried out based on the experimental J(c)(B) data taken from literature and using the critical state method and H-formulation together in COMSOL Multiphysics package, to further elucidate the mechanism of supercurrent generation and guidance force. The bigger guidance force and lateral magnetic stiffness values of PMG-B arrangement with three B-z peaks than the other arrangements with one Bz peak in small cooling height of 5 mm are attributed to the more robust individual intragrain supercurrents, rather than intergrain supercurrent, due to the position coincidence in the z-direction between grains and permanent magnet poles. Additionally, it can be said that PMG-C arrangement with one Bz peak getting to the maximum guidance force value when the cooling height increase from 5 mm to 15 mm, points out for large cooling height the intergrain supercurrents dominate, whereas for the small cooling height the intragrain supercurrents have most effect on the guidance force. Also, performed the supercurrent simulations, using different current flow constraint ratio f (or supercurrent coupling parameter), clearly reproduced the qualitative change in the trapped field profile when the allowed intergrain current compared to no intergrain current (f = 0). It is thought that the presented results, related to the supercurrent generation, coupling mechanism and their effect on levitation and lateral force properties, have utilization potential for researches not only they study on new multiseed superconductor fabrication method, but also they study on superconductor applications. (C) 2016 Elsevier B. V. All rights reserved.

AtıfScopus29·WoS30·OpenAlex30

İncele

Ozturk, K.; Sahin, E.; Abdioglu, M.; Kabaer, M.; Celik, S.; Yanmaz, E.; Kucukomeroglu, T.

Abstract It is crucial to improve the magnetic levitation, guidance and stiffness performances of the HTS Maglev systems for real-scale applications. In this study, the magnetic levitation force, guidance force and magnetic stiffness values were determined for single and multi-seeded YBCOs on different PMGs in ZFC regime and different cooling heights (CHs) after the magnetic flux distributions simulation of the using PMGs. Implemented study showed that the additional downward PMs make an enhancing contribution on the magnetic levitation force, guidance force and magnetic stiffness of both single and multi-seeded YBCOs. It was also determined that both the force and stiffness ratios of multi-seeded YBCO to single-seeded YBCO increase with increasing CH, indicating that the multi-seeded YBCO has much more interaction domain than single-seeded at higher gaps. It is considered that the results obtained in this study are very useful in technological applications of Maglev and bearing systems, because there is no detailed study on the magnetic stiffness, levitation and guidance force comparison to clarify electromagnetic behavior of single and multi-seeded YBCOs for different HTS-PMG arrangements.

AtıfScopus42·WoS39·OpenAlex40

İncele

Abdioglu, M.; Ozturk, K.; Gedikli, H.; Ekici, M.; Cansiz, A.

The development of superconductor Maglev systems depends on various disciplinary studies due to the inherent composition of available technologies. Because the fabrication cost is very effective on the Maglev, the requirement of the efficiency improvement focuses the researchers on the design considerations. In this study, the guidance force, the magnetic levitation force (MLF) and magnetic stiffness of different permanent magnetic guideway (PMG) arrangements were investigated in different cooling heights (CH) to enhance the efficiency of Maglev system. The single domain cylindrical bulk YBCO superconductors fabricated by top seeding method with the diameter of 45 mm and the height of 15 mm were used as HTS. Magnetic field distributions of the PMGs were calculated by finite element method to determine optimum HTS-PMG arrangements. We have used auxiliary onboard permanent magnets with YBCOs to improve the MLF of three pole Halbach PMG arrangements. It is seen that the efficiency of Maglev systems can be improved by using suitable HTS-PMG arrangements. In this study cost efficiency of the integrated levitation and guidance force ((Fz)max(Fx)max/(SPMG ∗ Cost)) was also determined. It is inferred from this study that the cooling height and PMG-HTS arrangement are key parameters for guidance force, levitation force, magnetic stiffness and efficiency of Maglev systems. It is believed that this study will supply useful references for practical application of HTS Maglev systems.

AtıfScopus60·WoS59·OpenAlex61

İncele

Ozturk, K.; Kabaer, M.; Abdioglu, M.

Abstract In implemented studies before, although some advancements have been achieved in improving on the levitation or guidance force efficiency of YBCOs separately, both of these forces could not been enhanced simultaneously. In our study, we investigated levitation, guidance force and magnetic stiffness properties of multi-seeded YBCO bulk depending on different position of onboard PM in different CHs above a Halbach PMG to obtain larger vertical load capability, stability and relating stiffness values at the same time. The levitation, guidance force and relating stiffness measurements were carried out between multi-seeded YBCO and Halbach PMG depending on the onboard PM positions and cooling heights after the magnetic flux distributions modelling of Halbach PMG with onboard PMs. In this paper, it has clearly seen that the levitation force and the vertical magnetic stiffness values increase in optimal onboard PM position, with negligible lose in guidance force and lateral magnetic stiffness values. It is inferred from this study that reasonable position of the onboard PM according to PMG, the cooling conditions and compatibility of YBCO-PMG arrangement in point of magnetic flux distribution are key parameters for efficiency of the load, guidance force and relating magnetic stiffness of Maglev systems. The results obtained in this study have a potential on improvement of HTS Maglev system electromagnetic force capability.

AtıfScopus19·WoS18·OpenAlex19

İncele

Abdioglu, M.; Ozturk, K.; Kutuk, S.; Bolat, S.; Yanmaz, E.

Sm123 and Sm211 were prepared by melt-powder-melt-growth and solid-state-reaction techniques, respectively, to have the nominal composition of (Sm123) 0.75 (Sm211) 0.25. After the preparation of this composition, the Fe-B magnetic powder (MP) was added to the composition for 0.000, 0.010, 0.015, 0.025, 0.050 wt.% to investigate the effect of MP addition on the levitation force density (LFD). Additionally, different permanent magnets (PM) were used as magnetic-field source to investigate the effect of magnetic-field gradient on the LFD of MP added superconductors. Our findings indicate that the MP addition acts as a flux pinning centre in the sample and enhances the LFD up to 0.025 wt.% adding amount, and the optimum flux gradient which produces a screening current in the sample occurs when the B/d (magnetic-field intensity/ diameter of PM) ratio is equal to 0.060. These results imply that the experimental data can be useful for fabricating process of superconducting samples with larger MLF values, and designing of superconducting magnets, flywheel energy storage and maglev systems.

AtıfScopus10·WoS10·OpenAlex10

İncele