Sukru Celik
@sinop.edu.tr
Energy Systems Engineering department / Engineering and Architecture Faculty
Sinop University
RESEARCH INTERESTS
Superconductivity and its large scale applications.
Scopus Publications
Scopus Publications
Murat Abdioglu, Kemal Ozturk, Mehmet Ekici, Burcu Savaskan, Sukru Celik, and Ahmet Cansiz
Institute of Electrical and Electronics Engineers (IEEE)
Murat Abdioglu, Sait Baris Guner, Kemal Ozturk, Chiaming Yang, Ingann Chen, and Sukru Celik
Wiley
Ozge Erdem, Sait Baris Guner, Sukru Celik, and Tayfur Kucukomeroglu
Elsevier BV
Abstract This research presents the influence of pyrene (C16H10) addition (0, 2, 4, 6, 8, 10 wt%) on the superconducting properties of bulk MgB2. For C16H10 added MgB2 samples, a shrinkage in a-lattice parameters was determined, whereas c-lattice parameters remained practically unchanged. The (1 1 0) peak observed at 2θ ≈ 59.9◦ slightly shifted to higher angles, the lattice strain increased and the crystallite size reduced after C16H10 addition. By virtue of induced stronger pinning force, the in-field critical current density (Jc) increased after C16H10 addition. The Jc value at 20 K and 4 T was obtained about two times higher (8.54 × 103 A/cm2) for 4 wt% C16H10 added MgB2 sample than that of the pure one. In addition, the variation of levitation force characteristic of MgB2 with increasing C16H10 content was determined at 20, 25 and 30 K. The best vertical levitation force performance in zero-field-cooled regime was obtained as 7.09 N/g at 20 K for 4 wt% C16H10 added MgB2 sample with 13 mm in diameter.
Sait Barış Güner, Murat Abdioğlu, Kemal Öztürk, and Şükrü Çelik
Elsevier BV
Abstract 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.
K. Ozturk, C. Aksoy, L.A. Angurel, B. Savaskan, E. Martínez, A. Badía-Majós, G.F. de la Fuente, B. Guner, C.E.J. Dancer, and S. Celik
Elsevier BV
Abstract Infrared (IR) laser-line scanning has been widely used to induce different surface microstructures in a broad range of materials. In this work, this laser configuration was applied on the surface of MgTi0.06B2 bulk samples in order to ascertain its effects on their superconducting properties, particularly on the magnetic levitation forces. The microstructural changes produced by this type of laser treatment were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). It was observed that the thermal treatment induced by the laser improves grain connectivity in a layer of material just below the irradiated surface, in agreement with the observed improvement in critical current density values, Jc, which were estimated from isothermal magnetic hysteresis loops. A significant increment of both vertical (Fz) and lateral (Fx) magnetic levitation forces was achieved. Numerical calculations were performed to understand the experimental behaviour and to clarify how an improvement of Jc near the surface can improve the magnetic levitation force of these materials. In addition, the same studies were carried out in similar bulk samples but with nano-sized silver particle additions of 3 and 6 wt %, in the outer ring of the bulk, observing also an improvement of the levitation forces, albeit less than in samples without Ag because of the better performance of the original samples after laser treatment. These results are relevant to those studying superconductor fabrication and material fabrication modelling, essential for the development of technological applications of superconductors, and are based on microstructure control via application of a recently developed laser-line scan method.
M. Abdioglu, K. Ozturk, S.B. Guner, S. Celik, and T. Kucukomeroglu
Elsevier BV
Abstract 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.
K. Ozturk, S.B. Guner, M. Abdioglu, M. Demirci, S. Celik, and A. Cansiz
Elsevier BV
Abstract 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.
Sait Barış Güner, Burcu Savaşkan, Kemal Öztürk, Şükrü Çelik, Canan Aksoy, Fırat Karaboğa, Ezgi Taylan Koparan, and Ekrem Yanmaz
Elsevier BV
Abstract 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 (Fz) force and lateral force (Fx) 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 (Jc). 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.
Burcu Savaşkan, Ezgi Taylan Koparan, Sait Barış Güner, Kemal Öztürk, and Şükrü Çelik
Springer Science and Business Media LLC
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 (Jc), vertical levitation force (Fz) and guidance force (Fx) 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$F_{z}$ 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$J_{c}$ value of 5.3×104$5.3\\times 10^{4}$ 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.
B. Çakır, K. Öztürk, S.B. Güner, Ş. Çelik, and A. Aydıner
Elsevier BV
Abstract Although the welding techniques have been used to join for bulk YBCO superconductors with a sintered superconductor, similar technique as a Ag2O added bulk YBCO superconductor fabricated by melt-powder-melt-growth process (MPMG) for using as a solder material has not been used, until now. Also, physical and the bulk superconducting properties of the welded samples have not been investigated. In this study, two 20 wt% Y211 and two 30 wt% Y211 added YBCO main samples were fabricated by cold top seeding-melt-growth (TSMG) method by using an Nd123 seed. Two main samples having the same Y211 addition and welding sample positioned between the main samples stacked and welded thermally with a pressure source simultaneously. It can be seen from the levitation force measurement, making before the welding process, that the 30 wt% Y211 added samples have the larger the maximum repulsive forces values than the 20 wt% Y211 added and Ag2O added welding samples but at the same order. After the welding process the welded samples cut into the specimens, to investigate micro structure and electromagnetic properties, positioned above, on and below of the welding region of the each welded Y123 samples. From the SEM analysis a continuous structural phase was obtained between the solder material and the main samples with a good integration without any boundary gap or defects. The welding process had no negative noticeable effect on Tc of the samples under zero magnetic field, while superconducting transition width (∆Tc) of the specimen cutting from the 30 wt% Y211 added sample (Y30-ab) is smaller the specimen cutting from the 20 wt% Y211 added sample (Y20-ab) under applied magnetic field points out that Y30-ab is more resistant to the applied field than the Y20-ab because of the 211 addition. In addition, 30 wt% 211 addition ratio is more efficient for welding region and whole welded sample in terms of the supplying uniform superconducting properties as Jc. The obtained results on welded joined bulk superconductor can be beneficial to increase application potential of these superconducting materials in real scale magnetic systems.
O. Ozturk, R. A. M. Arebat, A. R. A. Nefrow, F. Bulut, G. Guducu, E. Asikuzun, and S. Celik
Springer Science and Business Media LLC
In this study, we have examined the structural, superconducting and mechanical properties of Y3Ba5Cu8−xCoxO18 − δ system (x = 0, 0.05, 0.1, 0.15, 0.2 and 0.5), which is produced by conventional solid-state reaction method. Produced samples have been examined using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Vicker’s hardness (Hv) and electrical resistance measurement (R–T). According to the XRD patterns, we have obtained that the Co nanopowder doping has been caused some changes on the average grain size, characteristic peak intensities and lattice parameters of the Y3Ba5Cu8O18 − δ crystal system. Furthermore, according to the electrical resistance measurements, the critical temperature (Tc) values of all the samples have tended to decrease constantly with the increment in the doping ratio in the Y358 crystal structure. As for the variation in the microhardness parameters of superconducting materials, the Hv parameters and other related computations (Young’s modulus and yield strengths) have been found to increase regularly with the Co/Cu substitution level. Besides, the characteristic Hv curves have confirmed that the whole bulk of Bi-2212 samples showed untypical reverse indentation size effect (RISE) behavior.
O. Erdem, M. Abdioglu, S.B. Guner, S. Celik, and T. Kucukomeroglu
Elsevier BV
Abstract The effect of coronene (C 24 H 12 ) addition on the levitation force properties of MgB 2 superconductor has been investigated for the first time in this study. The polycrystalline disk-shaped MgB 2 + y wt % C 24 H 12 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 MgB 2 . The J c values were obtained as 4.6 × 10 3 Acm −2 and 1.3 × 10 4 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 C 24 H 12 is an effective carbon-containing additive for MgB 2 and can be useful for optimizing the levitation performance of MgB 2 superconductors for potential applications.
M. Abdioglu, M. Kabaer, K. Ozturk, O. Erdem, and S. Celik
Springer Science and Business Media LLC
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.
Sait Baris Guner, Sukru Celik, Ahmet Cansız, and Kemal Ozturk
Springer Science and Business Media LLC
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.
K. Ozturk, C.E.J. Dancer, B. Savaskan, C. Aksoy, B. Guner, P. Badica, G. Aldica, and S. Celik
Elsevier BV
Abstract Fabrication methods are important way to improve structural and superconducting properties of MgB 2 such as critical current, magnetic levitation force (MLF) and magnetic field trapping capability. Although the graded fabrication technique has been used for single-grain bulk YBCO superconductor to improve critical current and bulk superconducting properties, similar technique as regional doping has not been used for bulk MgB 2 , until now. In this study, nanoparticle silver doping was carried out in to the bulk MgTi 0.06 B 2 superconductor by using in-situ solid state reaction and partial graded (regional) doping method together, to improve the radius independent uniform bulk current density and the magnetic levitation force as well as the structural properties of the MgB 2 bulk superconductors. Both the J c (0) self-field critical current and F p ( μ 0 H ) pinning force density values enhanced in comparison with the inner region values, when the nanoparticle Ag doping is carried out in to the outer section of the sample. Addition to the enhancement of the structural and the micro electromagnetic properties as J c (0) and F p ( μ 0 H ), our study also focused on the improved of the bulk J c and the radius of shielding current loop r, to improve bulk electromagnetic properties as the levitation force. It is seen that the structural properties enhanced and both the vertical levitation force and the lateral guidance force value increased with Ag doping to the outer section of MgTi 0.06 B 2 sample. On the other hand, the increasing ratio of the lateral guidance force of 19.7% and the vertical levitation force of 10.8% of the sample with 3 wt% Ag-doped than the undoped one points out that the regional doping method to the outer section is very suitable for guidance force applications, which is important in the magnetic bearing application such as Maglev and magnetic energy storage systems.
Sait Baris Guner, Sukru Celik, and Murat Tomakin
Elsevier BV
Abstract The temperature dependence of the magnetic levitation force has been investigated for single-grain YBCO bulk sample, 20 mm in diameter with a thickness of 8 mm, fabricated by top-seeded melt growth (TSMG) method using Nd123 seeded. The superconducting properties of the single grain YBCO bulk are studied by VSM (Vibrating Sample Magnetometer), the microstructures and the phase constituents of those that are seen by SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction). The measurements of superconducting properties indicated that magnetic levitation forces of the sample were found 11.23, 10.81, 10.34, 9.23 and 7.02 N at the temperatures of 37, 47, 57, 67 and 77, respectively, and the values of the onset critical temperature (Tc) and the zero-field critical current density (Jc) are 89.3 K and 5.6 × 10 4 A/cm 2 at 77 K, respectively. This research is intended to help for the large scale superconductor levitation performances at different temperatures.
B. Savaskan, E.T. Koparan, S.B. Güner, S. Celik, and E. Yanmaz
Elsevier BV
Abstract In this study, the size effect on the magnetic levitation performance of disk-shaped MgB 2 bulk superconductors and permanent magnets was investigated. MgB 2 samples with varying diameters of 13 mm, 15 mm and 18 mm, each of which were 2 g in mass, were prepared by two-step solid state reaction method. Vertical levitation force measurements under both zero-field-cooled (ZFC) and field-cooled (FC) regimes were carried out at different temperatures of 20, 24 and 28 K. It was determined that the levitation force of the MgB 2 strongly depends on both the diameters of the sample and the permanent magnet. In ZFC regime, the maximum levitation force value for the permanent magnet and the sample 18 mm in diameters reached to the 8.41 N at 20 K. In addition, in FC regime, attractive and repulsive force increased with increasing diameters of the sample and the permanent magnet. In that, the sample with 18 mm in diameter showed the highest attractive force value −3.46 N at 20 K and FC regime. The results obtained in this study are very useful in magnetic levitation devices as there is no detailed study on the size of superconductors and permanent magnets.
Sukru Celik
Elsevier BV
Abstract Most of the magnetic levitation force measurements in previous studies were performed at liquid nitrogen temperatures. Magnetic levitation force measurement system is needed for the levitation force of MgB2 and iron based superconducting samples. Magnetic levitation force measurement system was designed in this study. In this system, beside vertical force versus vertical motion, lateral and vertical force versus lateral motion measurements, the vertical force versus temperature at the fixed distance between permanent magnet PM and superconducting sample SC, and the vertical force versus time measurements were performed at any temperatures from 20 K to 300 K. Thanks to these measurements, the temperature dependence, time dependence, and the distance (magnetic field) and temperature dependences of SC can be investigated. On the other hand, the magnetic stiffness (MS) measurements can be performed in this system. MS dependence on temperature can be investigated by using the measurement of MS at different temperature in the range. These measurements at any temperatures in the range help the superconductivity properties of the superconductors, whose transition temperature is below the liquid nitrogen temperature, be characterized.
E. Taylan Koparan, B. Savaskan, S. B. Guner, and S. Celik
Springer Science and Business Media LLC
We present a detailed investigation of the effects of Bi2Sr2Ca1Cu2O8+κ (Bi-2212) adding on the levitation force and magnetic properties of bulk MgB2 obtained by hot press method. The amount of Bi-2212 was varied between 0 and 10 wt% (0, 2, 4, 6, 10 wt%) of the total MgB2. Moreover, we present MgB2 bulk samples fabricated by using different production methods including hot pressing method to our knowledge. All samples were prepared by using elemental magnesium (Mg) powder, amorphous nano-boron (B) powder and Bi-2212 powder which are produced by hot press method. As a result of hot press process, compact pellet samples were manufactured. The vertical and lateral levitation force measurements were executed at the temperatures of 20, 24 and 28 K under zero-field-cooled (ZFC) and field-cooled (FC) regimes for samples with various adding levels. At 24 K and 28 K under ZFC regime, the 2 wt% Bi-2212 added sample exhibits a higher vertical levitation force than the pure sample. Bi-2212 added MgB2 samples compared to the pure sample have lower attractive force values in FC regime. The magnetic field dependence of the critical current density Jc was calculated from the M-H loops for Bi-2212 added MgB2 samples. The 2 wt% Bi-2212 added sample has the best levitation and critical current density performance compared to other samples. The critical temperature (Tc) has slightly dropped from 37.8 K for the pure MgB2 sample to 36.7 K for the 10 wt% of Bi-2212 added sample. The transition temperature slightly decreases when Bi-2212 adding level is increased.
B. Savaşkan, E. Taylan Koparan, S. B. Güner, Ş. Çelik, K. Öztürk, and E. Yanmaz
Springer Science and Business Media LLC
We fabricated malic acid $$(\\hbox {C}_{4}\\hbox {H}_{6}\\hbox {O}_{5})$$(C4H6O5)-added $$\\hbox {MgB}_{2}$$MgB2 bulks by wet mixing and “Two-step solid state reaction method”. The effects of adding malic acid on $${ T}_{\\mathrm{c}}$$Tc, $${ J}_{\\mathrm{c}}-{ H}$$Jc-H behaviour and lateral levitation force $$({ F}_{\\mathrm{x}})$$(Fx) features of bulk $$\\hbox {MgB}_{2}$$MgB2 have been investigated. A systematic decrease in the critical temperature $${ T}_{\\mathrm{c}}$$Tc with increasing adding level confirms the substitution of C at the B site of $$\\hbox {MgB}_{2}$$MgB2. While the 4 wt% sample showed the best $${ J}_{\\mathrm{c}}$$Jc of $$3.7\\times 10^{4}$$3.7×104$$\\hbox {A/cm}^{2}$$A/cm2 at 4 T and 5 K, 15 wt% sample showed uncompetitive lower critical current density $$({ J}_{\\mathrm{c}})$$(Jc), which ascribes the poor connectivity due to the excessive unsubstituted C distribution at grain boundaries and the presence of high MgO amount. At 24 and 28 K, the 4 and 6 wt% malic-acid-added samples exhibit a higher lateral force than pure sample. Based on the observed values of M–H, $${ J}_{\\mathrm{c}}$$Jc (H) and lateral levitation force $$({ F}_{\\mathrm{x}})$$(Fx), it can be concluded that the 4 wt% malic-acid-added sample is the best of the studied samples.
K. Ozturk, E. Sahin, M. Abdioglu, M. Kabaer, S. Celik, E. Yanmaz, and T. Kucukomeroglu
Elsevier BV
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.
Kemal Ozturk, Murat Abdioglu, Ercin Sahin, Sukru Celik, Hasan Gedikli, and Burcu Savaskan
Institute of Electrical and Electronics Engineers (IEEE)
In this paper, the levitation force measurements have been carried out by the magnetic force measurement system under both field-cooling and zero-field-cooling regimes, whereas the magnetic field distribution over the permanent-magnet guideway (PMG) was calculated by numerical analysis based on the finite-element method. It was shown in this study that the vertical levitation capability and stability of Maglev systems can be improved depending on the cooling regime, pole number, and suitable arrangement of the PMG. In this paper, it was shown that when the pole number increases, the levitation force density increases. It also appeared that the reasonable position of the supplementary permanent magnet and appropriate cooling heights are key parameters for both levitation performance and stabilization of the high-temperature superconductor (HTS) Maglev. It is believed that the numerical and experimental data in this paper are useful for relative design and practical application of HTS Maglev systems.
B. Savaskan, E. Taylan Koparan, S. Celik, K. Ozturk, and E. Yanmaz
Elsevier BV
Abstract The effects of malic acid addition (from 0 to 15 wt% of the total MgB 2 ) on the levitation force properties of bulk MgB 2 have been investigated. All samples were prepared from magnesium powder, amorphous boron powder, malic acid (C 4 H 6 O 5 ) and toluene (C 7 H 8 ) by using two-step solid state reaction method. Vertical and lateral levitation force measurements that are under both zero-field-cooled (ZFC) and field-cooled (FC) regimes were carried out at different temperatures of 24, 28 and 32 K for samples with various adding level. It was found that the reasonable malic acid adding has a positive impact on the levitation properties. At 24 K and 28 K, the 4 wt% and 6 wt% malic acid added samples exhibits a higher levitation force than pure sample. In the case of the optimally additive 4 wt% sample, the maximum levitation force corresponds to 18.60 N, whereas the pure sample shows 16.95 N at 24 K for ZFC regime. In this study the enhancing effect of malic acid adding on the levitation force properties of MgB 2 has been first time investigated and reported.
I. Duz, S. B. Guner, O. Erdem, I. Demir, V. Kapucu, Ş. Çelik, K. Ozturk, S. Hossain, A. Gencer, and E. Yanmaz
Springer Science and Business Media LLC
MgB2 bulk superconductors were prepared by hot press plus furnace heating method. Two types of boron powders were used, one is amorphous nano boron and the other is C-doped boron. Characteristics of superconductors were determined by XRD and resistance measurements. Systematic levitation force measurements were performed by using a modular system at low temperatures. These bulk superconductors showed around 9 N repulsive and 4 N attractive forces in the z-axis at 20 K at closest point to the cryostat lid which contains the MgB2 superconductor. These values slightly decreased by increasing temperature to 24 and 28 K for both samples. Comparing two samples, nano boron MgB2 showed slightly higher levitation force than C-doped MgB2 although C-doped MgB2 has higher attractive force value at the closest point. This situation points out that C-doped MgB2 is much proper for attractive force applications (as guidance force) while the nanoboron MgB2 sample is much appropriate for repulsive force (as levitation).
O. Erdem, K. Ozturk, S. B. Guner, S. Celik, and E. Yanmaz
Springer Science and Business Media LLC
The levitation properties of MgB$$_{2}$$2 prepared by hot press at 200 $$^{\\circ }$$∘C and then pellet/closed tube method has been investigated. The vertical and lateral levitation forces ($$F_{z}$$Fz and $$F_{x})$$Fx) on a cylindrical NdFeB permanent magnet (PM) below a disk-shaped bulk MgB$$_{2}$$2 were measured during the vertical and lateral traverses of the PM in different cooling heights (CHs) and measurement heights (MHs) at temperatures of 20, 25 and 30 K to investigate the effect of the initial CH and MH on the levitation performance of MgB$$_{2}$$2. For temperatures below 30 K, it was observed that $$F_{z}$$Fz increases with increasing CH. However, a minute variation in $$F_{z}$$Fz and a big hysteresis loop are observed at 30 K. From the lateral traverses, it was obtained that the $$F_{z}$$Fz with attractive character increases with decreasing MH and the hysteresis effect increases for small MHs due to the increment of the magnetic field intensity which the sample feels with decreasing MH. In addition, it was seen that the character of $$F_{x}$$Fx varies depending on both MH and measurement temperature. The higher hysteresis obtained in $$F_{x}$$Fx than in $$F_{z}$$Fz during lateral traverses implies that the motion of the flux lines in MgB$$_{2}$$2 is especially in lateral rather than vertical direction. Finally in this study, it was shown that the levitation performance of MgB$$_{2}$$2 depends not only on the measurement temperature but also on the CH and MH conditions. These results can be useful for optimizing the levitation performance of MgB$$_{2}$$2 superconductors for potential applications.