# Papers Published in 2017

Here below are some review publications related to analytical and numerical models of superconductors. Some of them are a concrete results of the collaborative effort of this work group.

LIST OF PAPERS

• M. D. Ainslie, D. Hu, V. M. R. Zermeno, and F. Grilli, “Numerical Simulation of the Performance of High-Temperature Superconducting Coils,” Journal of Superconductivity and Novel Magnetism, vol. 30, iss. 7, pp. 1987-1992, 2017.
[Bibtex]
@article{Ainslie:JSNM17,
Abstract = {The Bulk Superconductivity Group at the University of Cambridge is currently investigating the use of high-temperature superconducting (HTS) materials in wire and bulk form in order to increase the electrical and magnetic loadings of an axial gap, trapped flux-type superconducting electric machine. As part of this research, accurate 2D axisymmetric and 3D finite element models of superconducting coils have been developed to investigate and simulate their electromagnetic behaviour. Some of the recent advances in analysing the performance of HTS coils are highlighted, including the simulation of in-field performance and increasing the computational speed and accuracy of 3D models. Experimental and simulation results on the DC characterisation of a test circular, epoxy-impregnated HTS coil are used to interpret the effects of degradation due to epoxy impregnation from the coil's ideal performance. With this numerical modelling framework, it is possible to simulate a variety of complex devices in both 2D and 3D over a broad range of electromagnetic situations with good accuracy.},
Author = {M. D. Ainslie and D. Hu and V. M. R. Zermeno and F. Grilli},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1007/s10948-016-3842-2},
Journal = {Journal of Superconductivity and Novel Magnetism},
Number = {7},
Pages = {1987-1992},
Title = {Numerical Simulation of the Performance of High-Temperature Superconducting Coils},
Url = {http://dx.doi.org/10.1007/s10948-016-3842-2},
Volume = {30},
Year = {2017}}
• A. Azzouza, H. Allag, J. P. Yonnet, and P. Tixador, “3-D New Calculation Principle of Levitation Force Between Permanent Magnet and Hard Type-II Superconductor Using Integral Approach,” IEEE Transactions on Magnetics, vol. 53, iss. 11, p. 8109705, 2017.
[Bibtex]
@article{Azzouza:TMAG17,
Author = {A. Azzouza and H. Allag and J. P. Yonnet and P. Tixador},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1109/TMAG.2017.2708323},
Journal = {IEEE Transactions on Magnetics},
Number = {11},
Pages = {8109705},
Title = {{3-D New Calculation Principle of Levitation Force Between Permanent Magnet and Hard Type-II Superconductor Using Integral Approach}},
Url = {http://doi.org/10.1109/TMAG.2017.2708323},
Volume = {53},
Year = {2017}}
• P. Bernstein, L. Colson, L. Dupont, and J. Noudem, “Investigation of the levitation force of field-cooled YBCO and MgB2 disks as functions of temperature,” Superconductor Science and Technology, vol. 30, iss. 6, p. 065007, 2017.
[Bibtex]
@article{Bernstein:SST17,
Abstract = {We report levitation force cycles resulting from measurements carried out on a YBCO and a MgB 2 disk cooled down in the field of a permanent magnet. In both cases the amplitude of the levitation force tends toward maximum values as the temperature decreases. Otherwise, the cycles are almost closed at low temperature and strongly hysteretic in the high temperature range. The hysteresis of the force cycles is attributed to the distribution of the currents induced in the sample by the field of the magnet. The saturation of the levitation forces at low temperature is related to that of the magnetic moment of the disks. We show that this type of measurement allows for the determination of the critical current density of superconductors in a restricted domain of temperatures.},
Author = {P. Bernstein and L. Colson and L. Dupont and J. Noudem},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {https://doi.org/10.1088/1361-6668/aa69ec},
Journal = {Superconductor Science and Technology},
Number = {6},
Pages = {065007},
Title = {{Investigation of the levitation force of field-cooled YBCO and MgB2 disks as functions of temperature}},
Url = {10.1088/1361-6668/aa69ec},
Volume = {30},
Year = {2017}}
• C. -H. Bonnard, F. Sirois, C. Lacroix, and G. Didier, “Multi-scale model of resistive-type superconducting fault current limiters based on 2G HTS coated conductors,” Superconductor Science and Technology, vol. 30, iss. 1, p. 014005, 2017.
[Bibtex]
@article{Bonnard:SST17,
Abstract = {In order to plan the integration of superconducting fault current limiters (SFCLs) in power systems, accurate models of SFCLs must be made available in commercial power system transient simulators. In this context, we developed such a model for the EMTP-RV software package, a power system transient simulator widely used by power utilities. The model can be used with any resistive-type SFCL (rSFCL) made of high temperature superconductor (HTS) tapes, which are discretized in electro-thermal elements'. Those elements consist solely of electric circuit components, and are used to represent portions of tape of various sizes and dimensions (a multi-scale' approach). Both the electrical and thermal behaviors of the tape are modeled, including interfacial effects, nonlinear properties of materials and heat transfer to the surrounding environment. Such a multi-scale model can simulate accurately both the local quench dynamics of HTS tapes (microscopic scale) and the global impact of the rSFCL on the power system (macroscopic/system scale). In this paper, the model is used to compute phenomena such as propagation velocity of a hot spot and heat diffusion through the thickness of the tape. Results were verified by comparing EMTP-RV results with finite element simulations. In addition to the development of the multi-scale model itself, which is the major contribution of this paper, the use of the model allowed us to determine the conditions of validity of the commonly used homogenization' of the thermal properties across the tape thickness. Indeed, when the current flowing into the rSFCL is slightly above its critical current I c (and up to ##IMG## [http://ej.iop.org/images/0953-2048/30/1/014005/sustaa4072ieqn1.gif] {$2{I}_{{\rm{c}}}$} ), very important errors in the power waveforms arise, leading to potentially wrong decisions of protection systems. Homogenized thermal models should thus be used with great care in practice.},
Author = {C.-H. Bonnard and F. Sirois and C. Lacroix and G. Didier},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/0953-2048/30/1/014005},
Journal = {Superconductor Science and Technology},
Number = {1},
Pages = {014005},
Title = {{Multi-scale model of resistive-type superconducting fault current limiters based on 2G HTS coated conductors}},
Url = {http://dx.doi.org/10.1088/0953-2048/30/1/014005},
Volume = {30},
Year = {2017}}
• M. Breschi, L. Cavallucci, P. L. Ribani, A. V. Gavrilin, and H. W. Weijers, “Modeling of Quench in the Coupled HTS Insert/LTS Outsert Magnet System of the NHMFL,” IEEE Transactions on Applied Superconductivity, vol. 27, iss. 5, p. 4301013, 2017.
[Bibtex]
@article{Breschi:TAS17,
Author = {M. Breschi and L. Cavallucci and P. L. Ribani and A. V. Gavrilin and H. W. Weijers},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1109/TASC.2017.2698214},
Journal = {IEEE Transactions on Applied Superconductivity},
Number = {5},
Pages = {4301013},
Title = {{Modeling of Quench in the Coupled HTS Insert/LTS Outsert Magnet System of the NHMFL}},
Url = {http://dx.doi.org/10.1109/TASC.2017.2698214},
Volume = {27},
Year = {2017}}
• B. J. H. de Bruyn, J. W. Jansen, and E. A. Lomonova, “AC losses in HTS coils for high-frequency and non-sinusoidal currents,” Superconductor Science and Technology, vol. 30, iss. 9, p. 095006, 2017.
[Bibtex]
@article{deBruyn:SST17,
Abstract = {AC losses in racetrack coils that are wound of YBCO tapes are measured for sinusoidal and non-sinusoidal transport currents with fundamental frequencies up to 1 kHz. An electrical method to measure losses for non-sinusoidal currents is developed for this purpose. The measured losses are compared to the losses calculated by 2D finite element models with power-law material models. The frequency and waveform-dependency of the measured losses are shown and compared to the results of the models over a wide range of frequencies and waveforms. Finally, it is shown that the finite element models can accurately predict AC losses resulting from non-sinusoidal transport currents as are present in highly dynamic motors with AC armature coils.},
Author = {B. J. H. de Bruyn and J. W. Jansen and E. A. Lomonova},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/aa7c74},
Journal = {Superconductor Science and Technology},
Number = {9},
Pages = {095006},
Title = {{AC losses in HTS coils for high-frequency and non-sinusoidal currents}},
Url = {https://doi.org/10.1088/1361-6668/aa7c74},
Volume = {30},
Year = {2017}}
• C. E. Bruzek, A. Ballarino, G. Escamez, S. Giannelli, F. Grilli, F. Lesur, A. Marian, and M. Tropeano, “Cable Conductor Design for the High-Power $\rm MgB_2$ DC Superconducting Cable Project within BEST PATHS,” IEEE Transactions on Applied Superconductivity, vol. 27, iss. 4, p. 4801405, 2017.
[Bibtex]
@article{Bruzek:TAS17,
Author = {C. E. Bruzek and A. Ballarino and G. Escamez and S. Giannelli and F. Grilli and F. Lesur and A. Marian and M. Tropeano},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1109/TASC.2016.2641338},
Journal = {IEEE Transactions on Applied Superconductivity},
Number = {4},
Pages = {4801405},
Title = {{Cable Conductor Design for the High-Power $\rm MgB_2$ DC Superconducting Cable Project within BEST PATHS}},
Url = {http://dx.doi.org/10.1109/TASC.2016.2641338},
Volume = {27},
Year = {2017}}
• A. Campbell, M. Baghdadi, A. Patel, D. Zhou, K. Y. Huang, Y. Shi, and T. Coombs, “Demagnetisation by crossed fields in superconductors,” Superconductor Science and Technology, vol. 30, iss. 3, p. 034005, 2017.
[Bibtex]
@article{Campbell:SST17,
Abstract = {A study has been made of the decay of the trapped magnetisation in superconductors when exposed to a crossed field. Numerical results have been compared with the theory of Brandt and Mikitik (2002 Phys. Rev. Lett. 89 [http://https://doi.org/10.1103/PhysRevLett.89.027002] 027002 ) which solves the problem for a thin strip superconductor. FlexPDE with the A formulation and COMSOL with the H formulation were both used. Simulations of a strip with a cross section aspect ratio of 20 showed good agreement with theory both for the case of a transverse field larger than the transverse penetration field and for one smaller. In the latter case the magnetisation saturates as predicted, however the simulations show a slow decay after many cycles. In the case of stacked YBCO tapes the movement of flux lines is very small and the effects of the reversible motion were investigated. This can decrease the decay initially for very thin decoupled tapes, but cause a steady decay after very large numbers of cycles. Simulations on stacked strips showed that the decay constant increased approximately linearly with the number of strips. When combined with the theory for one tape this can explain the very slow decay observed in previous experiments. Experimental results were qualitatively in agreement with theory and simulations but showed some discrepancies. However there are a number of differences between the experimental situation and theory so good agreement is not expected.},
Author = {A. Campbell and M. Baghdadi and A. Patel and D. Zhou and K. Y. Huang and Y. Shi and T. Coombs},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/aa52f2},
Journal = {Superconductor Science and Technology},
Number = {3},
Pages = {034005},
Title = {{Demagnetisation by crossed fields in superconductors}},
Url = {http://dx.doi.org/10.1088/1361-6668/aa52f2},
Volume = {30},
Year = {2017}}
• D. M. Djoki’c, L. Antognazza, and M. Decroux, “Finite Element Method simulation study of heat propagation in a novel YBCO-based Coated Conductor for resistive fault current limiters,” International Journal of Thermal Sciences, vol. 111, pp. 160-167, 2017.
[Bibtex]
@article{Djorkic:IJTS17,
Author = {Dejan M. Djoki{\'c} and L. Antognazza and M. Decroux},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1016/j.ijthermalsci.2016.08.023},
Journal = {International Journal of Thermal Sciences},
Pages = {160-167},
Title = {{Finite Element Method simulation study of heat propagation in a novel YBCO-based Coated Conductor for resistive fault current limiters}},
Url = {http://dx.doi.org/10.1016/j.ijthermalsci.2016.08.023},
Volume = {111},
Year = {2017}}
• M. Erdogan, S. Tunc, S. Yildiz, and F. Inanir, “A Comparative Study of AC Transport and Eddy Current Losses for Coil Made of HTS Tapes Coated with Copper Stabilizer,” Journal of Superconductivity and Novel Magnetism, vol. 30, iss. 11, pp. 3277-3283, 2017.
[Bibtex]
@article{Erdogan:JSNM17,
Author = {M. Erdogan and S. Tunc and S. Yildiz and F. Inanir},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1007/s10948-016-3855-x},
Journal = {Journal of Superconductivity and Novel Magnetism},
Number = {11},
Pages = {3277--3283},
Title = {{A Comparative Study of AC Transport and Eddy Current Losses for Coil Made of HTS Tapes Coated with Copper Stabilizer}},
Url = {http://dx.doi.org/10.1007/s10948-016-3855-x},
Volume = {30},
Year = {2017}}
• F. Grilli and V. M. R. Zermeño, “Effect of Tape’s $I_\rm c$ Inhomogeneity and Strand Misalignment on the Transport Capacity of Roebel Cables,” IEEE Transactions on Applied Superconductivity, vol. 27, iss. 5, p. 6603605, 2017.
[Bibtex]
@article{Grilli:TAS17,
Author = {F. Grilli and V. M. R. Zerme\~no},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1109/TASC.2017.2691583},
Journal = {IEEE Transactions on Applied Superconductivity},
Number = {5},
Pages = {6603605},
Title = {{Effect of Tape's $I_{\rm c}$ Inhomogeneity and Strand Misalignment on the Transport Capacity of Roebel Cables}},
Url = {http://dx.doi.org/10.1109/TASC.2017.2691583},
Volume = {27},
Year = {2017}}
• F. Gömöry and J. Sheng, “Two methods of AC loss calculation in numerical modelling of superconducting coils,” Superconductor Science and Technology, vol. 30, iss. 6, p. 064005, 2017.
[Bibtex]
@article{Gomory:SST17,
Author = {F. {G\"om\"ory} and J. Sheng},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/aa66af},
Journal = {Superconductor Science and Technology},
Number = {6},
Pages = {064005},
Title = {{Two methods of AC loss calculation in numerical modelling of superconducting coils}},
Url = {https://doi.org/10.1088/1361-6668/aa66af},
Volume = {30},
Year = {2017}}
• G. Iannone, A. Saggese, D. G. Marzi, and U. Gambardella, “Magnetic Characterization and FEM Computation of MgB2 Bulk Spheres,” IEEE Transactions on Applied Superconductivity, vol. 27, iss. 4, p. 5900104, 2017.
[Bibtex]
@article{Iannone:TAS17,
Author = {G. Iannone and A. Saggese and G. De Marzi and U. Gambardella},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1109/TASC.2016.2637360},
Journal = {IEEE Transactions on Applied Superconductivity},
Number = {4},
Pages = {5900104},
Title = {{Magnetic Characterization and FEM Computation of MgB2 Bulk Spheres}},
Url = {https://doi.org/10.1109/TASC.2016.2637360},
Volume = {27},
Year = {2017}}
• F. Liang, S. Venuturumilli, H. Zhang, M. Zhang, J. Kvitkovic, S. Pamidi, Y. Wang, and W. Yuan, “A finite element model for simulating second generation high temperature superconducting coils/stacks with large number of turns,” Journal of Applied Physics, vol. 122, iss. 4, p. 043903, 2017.
[Bibtex]
@article{Liang:JAP17,
Author = {F. Liang and S. Venuturumilli and H. Zhang and M. Zhang and J. Kvitkovic and S. Pamidi and Y. Wang and W. Yuan},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1063/1.4995802},
Journal = {Journal of Applied Physics},
Number = {4},
Pages = {043903},
Title = {{A finite element model for simulating second generation high temperature superconducting coils/stacks with large number of turns}},
Url = {http://dx.doi.org/10.1063/1.4995802},
Volume = {122},
Year = {2017}}
• G. Liu, G. Zhang, L. Jing, and H. Yu, “Numerical study on AC loss reduction of stacked HTS tapes by optimal design of flux diverter,” Superconductor Science and Technology, vol. 30, iss. 12, p. 125014, 2017.
[Bibtex]
@article{Liu:SST17,
Abstract = {High temperature superconducting (HTS) coils are key parts of many AC applications, such as generators, superconducting magnetic energy storage and transformers. AC loss reduction in HTS coils is essential for the commercialization of these HTS devices. Magnetic material is generally used as the flux diverter in an effort to reduce the AC loss in HTS coils. To achieve the greatest reduction in the AC loss of the coils, the flux diverter should be made of a material with low loss and high saturated magnetic density, and the optimization of the geometric size and location of the flux diverter is required. In this paper, we chose Ni-alloy as the flux diverter, which can be processed into a specific shape and size. The influence of the shape and location of the flux diverter on the AC loss characteristics of stacked (RE)BCO tapes is investigated by use of a finite element method. Taking both the AC loss of the (RE)BCO coils and the ferromagnetic loss of the flux diverter into account, the optimal geometry of the flux diverter is obtained. It is found that when the applied current is at half the value of the critical current, the total loss of the HTS stack with the optimal flux diverter is only 18% of the original loss of the HTS stack without the flux diverter. Besides, the effect of the flux diverter on the critical current of the (RE)BCO stack is investigated.},
Author = {G. Liu and G. Zhang and L. Jing and H. Yu},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/aa9362},
Journal = {Superconductor Science and Technology},
Number = {12},
Pages = {125014},
Title = {{Numerical study on AC loss reduction of stacked HTS tapes by optimal design of flux diverter}},
Url = {https://doi.org/10.1088/1361-6668/aa9362},
Volume = {30},
Year = {2017}}
• E. Pardo and M. Kapolka, “3D computation of non-linear eddy currents: Variational method and superconducting cubic bulk,” Journal of Computational Physics, vol. 344, pp. 339-363, 2017.
[Bibtex]
@article{Pardo:JCP17,
Author = {E. Pardo and M. Kapolka},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1016/j.jcp.2017.05.001},
Journal = {Journal of Computational Physics},
Pages = {339-363},
Title = {{3D computation of non-linear eddy currents: Variational method and superconducting cubic bulk}},
Url = {http://dx.doi.org/10.1016/j.jcp.2017.05.001},
Volume = {344},
Year = {2017}}
• E. Pardo and M. Kapolka, “3D magnetization currents, magnetization loop, and saturation field in superconducting rectangular prisms,” Superconductor Science and Technology, vol. 30, iss. 6, p. 064007, 2017.
[Bibtex]
@article{Pardo:SST17,
Abstract = {Bulk superconductors are used in many applications and material characterization experiments, with the bulk shape of the rectangular prism being the most frequent. However, the magnetization currents are still mostly unknown for this kind of 3D shape, especially below the saturation magnetic field. Knowledge of the magnetization currents in this kind of sample is needed to interpret the measurements and the development of bulk materials for applications. This article presents a systematic analysis of the magnetization currents in square-based prisms of several thicknesses. We make this study by numerical modeling using a variational principle that enables a high number of degrees of freedom. We also compute the magnetization loops and saturation magnetic field, using a definition that is more relevant for thin prisms than previous ones. The article presents a practical analytical fit for any aspect ratio. For applied fields below the saturation field, the current paths are not rectangular, presenting 3D bending. The thickness-average results are consistent with previous modeling and measurements for thin films. The 3D bending of the current lines indicates that there could be flux-cutting effects in rectangular prisms. The component of the critical current density in the applied field direction may play a role, with the magnetization currents being different in a bulk and a stack of tapes.},
Author = {E. Pardo and M. Kapolka},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/aa69ed},
Journal = {Superconductor Science and Technology},
Number = {6},
Pages = {064007},
Title = {{3D magnetization currents, magnetization loop, and saturation field in superconducting rectangular prisms}},
Url = {https://doi.org/10.1088/1361-6668/aa69ed},
Volume = {30},
Year = {2017}}
• A. Patel, S. Hahn, J. Voccio, A. Baskys, S. C. Hopkins, and B. A. Glowacki, “Magnetic levitation using a stack of high temperature superconducting tape annuli,” Superconductor Science and Technology, vol. 30, iss. 2, p. 024007, 2017.
[Bibtex]
@article{Patel:SST17,
Abstract = {Stacks of large width superconducting tape can carry persistent currents over similar length scales to bulk superconductors, therefore giving them potential for trapped field magnets and magnetic levitation. 46 mm wide high temperature superconducting tape has previously been cut into square annuli to create a 3.5 T persistent mode magnet. The same tape pieces were used here to form a composite bulk hollow cylinder with an inner bore of 26 mm. Magnetic levitation was achieved by field cooling with a pair of rare-earth magnets. This paper reports the axial levitation force properties of the stack of annuli, showing that the same axial forces expected for a uniform bulk cylinder of infinite J c can be generated at 20 K. Levitation forces up to 550 N were measured between the rare-earth magnets and stack. Finite element modelling in COMSOL Multiphysics using the H-formulation was also performed including a full critical state model for induced currents, with temperature and field dependent properties as well as the influence of the ferromagnetic substrate which enhances the force. Spark erosion was used for the first time to machine the stack of tapes proving that large stacks can be easily machined to high geometric tolerance. The stack geometry tested is a possible candidate for a rotary superconducting bearing.},
Author = {A. Patel and S. Hahn and J. Voccio and A. Baskys and S. C. Hopkins and B. A. Glowacki},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/30/2/024007},
Journal = {Superconductor Science and Technology},
Number = {2},
Pages = {024007},
Title = {{Magnetic levitation using a stack of high temperature superconducting tape annuli}},
Url = {http://doi.org/10.1088/1361-6668/30/2/024007},
Volume = {30},
Year = {2017}}
• A. Podlivaev and I. Rudnev, “A new method of reconstructing current paths in HTS tapes with defects,” Superconductor Science and Technology, vol. 30, iss. 3, p. 035021, 2017.
[Bibtex]
@article{Podlivaev:SST17,
Abstract = {We propose a new method for calculating current paths in high-temperature superconductive (HTS) tapes with various defects including cracks, non-superconducting inclusions, and superconducting inclusions with lower local critical current density. The calculation method is based on a model of critical state which takes into account the dependence of the critical current on the magnetic field. The method allows us to calculate the spatial distribution of currents flowing through the defective HTS tape for both currents induced by the external magnetic field and transport currents from an external source. For both cases, we performed simulations of the current distributions in these tapes with different types of defects and have shown that the combination of the action of the magnetic field and transport current leads to a more detailed identification of the boundaries and shape of the defects. The proposed method is adapted for calculating modern superconductors in real superconducting devices and may be more useful as compared to the conventional magnetometric diagnostic studies, when the tape is affected by the magnetic field only.},
Author = {A. Podlivaev and I. Rudnev},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/aa55aa},
Journal = {Superconductor Science and Technology},
Number = {3},
Pages = {035021},
Title = {{A new method of reconstructing current paths in HTS tapes with defects}},
Url = {http://dx.doi.org/10.1088/1361-6668/aa55aa},
Volume = {30},
Year = {2017}}
• J. Ruuskanen, A. Stenvall, V. Lahtinen, and E. Pardo, “Electromagnetic nonlinearities in a Roebel-cable-based accelerator magnet prototype: variational approach,” Superconductor Science and Technology, vol. 30, iss. 2, p. 024008, 2017.
[Bibtex]
@article{Ruuskanen:SST17,
Abstract = {Superconducting magnets are the most expensive series of components produced in the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN). When developing such magnets beyond state-of-the-art technology, one possible option is to use high-temperature superconductors (HTS) that are capable of tolerating much higher magnetic fields than low-temperature superconductors (LTS), carrying simultaneously high current densities. Significant cost reductions due to decreased prototype construction needs can be achieved by careful modelling of the magnets. Simulations are used, e.g. for designing magnets fulfilling the field quality requirements of the beampipe, and adequate protection by studying the losses occurring during charging and discharging. We model the hysteresis losses and the magnetic field nonlinearity in the beampipe as a function of the magnet's current. These simulations rely on the minimum magnetic energy variation principle, with optimization algorithms provided by the open-source optimization library interior point optimizer. We utilize this methodology to investigate a research and development accelerator magnet prototype made of REBCO Roebel cable. The applicability of this approach, when the magnetic field dependence of the superconductor's critical current density is considered, is discussed. We also scrutinize the influence of the necessary modelling decisions one needs to make with this approach. The results show that different decisions can lead to notably different results, and experiments are required to study the electromagnetic behaviour of such magnets further.},
Author = {J. Ruuskanen and A. Stenvall and V. Lahtinen and E. Pardo},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/30/2/024008},
Journal = {Superconductor Science and Technology},
Number = {2},
Pages = {024008},
Title = {Electromagnetic nonlinearities in a Roebel-cable-based accelerator magnet prototype: variational approach},
Url = {http://dx.doi.org/10.1088/1361-6668/30/2/024008},
Volume = {30},
Year = {2017}}
• B. Shen, J. Li, J. Geng, L. Fu, X. Zhang, H. Zhang, C. Li, F. Grilli, and T. A. Coombs, “Investigation of AC losses in horizontally parallel HTS tapes,” Superconductor Science and Technology, vol. 30, iss. 7, p. 075006, 2017.
[Bibtex]
@article{Shen:SST17,
Abstract = {This paper presents an AC loss study of horizontally parallel HTS tapes. We proposed to use three parallel HTS tapes as an example. The AC losses of the middle and end tape of three parallel tapes have been measured using the electrical method and compared to those of an individual tape. The effect of the interaction between tapes on AC losses has been analysed, and compared with finite-element method (FEM) simulations using the 2D H -formulation implemented in COMSOL Multiphysics. By using FEM simulations, the cases of increasing number of parallel tapes have been considered, and the normalised ratio between the total average AC losses per tape and the AC losses of an individual single tape has been calculated for different gap distances. We proposed a new parameter, N s , a turning point for number of tapes, to divide Stage 1 and Stage 2 for the AC loss study of horizontally parallel tapes. For Stage 1, N < N s , the total average losses per tape increased with the increasing number of tapes. For Stage 2,N > N s , the total average losses per tape decrease with the increasing number of tapes. The analysis demonstrates that horizontally parallel HTS tapes could be potentially used in superconducting devices like HTS transformers, which could retain or even reduce the total average AC losses per tape with large number of parallel tapes.},
Author = {B. Shen and J. Li and J. Geng and L. Fu and X. Zhang and H. Zhang and C. Li and F. Grilli and T. A. Coombs},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/aa6fc2},
Journal = {Superconductor Science and Technology},
Number = {7},
Pages = {075006},
Title = {{Investigation of AC losses in horizontally parallel HTS tapes}},
Url = {http://dx.doi.org/10.1088/1361-6668/aa6fc2},
Volume = {30},
Year = {2017}}
• J. Sheng, V. M. ciak, T. R. glu, L. Frolek, and F. Gömöry, “Numerical Study on Magnetization Characteristics of Superconducting Conductor on Round Core Cables,” IEEE Transactions on Applied Superconductivity, vol. 27, iss. 4, p. 4800305, 2017.
[Bibtex]
@article{Sheng:TAS17,
Author = {J. Sheng and M. Vojen{\v c}iak and R. Terzio{\u g}lu and L. Frolek and F. G{\"o}m{\"o}ry},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1109/TASC.2016.2632901},
Journal = {IEEE Transactions on Applied Superconductivity},
Number = {4},
Pages = {4800305},
Title = {{Numerical Study on Magnetization Characteristics of Superconducting Conductor on Round Core Cables}},
Url = {https://doi.org/10.1109/TASC.2016.2632901},
Volume = {27},
Year = {2017}}
• Z. Wang, L. Ren, Y. Tang, S. Yan, Y. Xu, K. Gong, and X. Deng, “A Coupling Simulation and Modeling Method for High Temperature Superconducting Magnets,” IEEE Transactions on Applied Superconductivity, vol. 27, iss. 4, p. 4900405, 2017.
[Bibtex]
@article{Wang:TAS17,
Author = {Z. {Wang} and L. {Ren} and Y. {Tang} and S. {Yan} and Y. {Xu} and K. {Gong} and X. {Deng}},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1109/TASC.2017.2653807},
Journal = {IEEE Transactions on Applied Superconductivity},
Number = {4},
Pages = {4900405},
Title = {{A Coupling Simulation and Modeling Method for High Temperature Superconducting Magnets}},
Url = {https://doi.org/10.1109/TASC.2017.2653807},
Volume = {27},
Year = {2017}}
• V. M. R. Zermeño, K. Habelok, M. Stepien, and F. Grilli, “A parameter-free method to extract the superconductor’s $J_c(B,\theta)$ field-dependence from in-field current-voltage characteristics of HTS tapes,” Superconductor Science and Technology, vol. 30, iss. 3, p. 034001, 2017.
[Bibtex]
@article{Zermeno:SST17,
Author = {V. M. R. Zerme{\~n}o and K. Habelok and M. Stepien and F. Grilli},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/30/3/034001},
Journal = {Superconductor Science and Technology},
Number = {3},
Pages = {034001},
Title = {{A parameter-free method to extract the superconductor's $J_c(B,\theta)$ field-dependence from in-field current-voltage characteristics of HTS tapes}},
Url = {https://doi.org/10.1088/1361-6668/30/3/034001},
Volume = {30},
Year = {2017}}
• H. Zhang, M. Zhang, and W. Yuan, “An efficient 3D finite element method model based on the T–A formulation for superconducting coated conductors,” Superconductor Science and Technology, vol. 30, iss. 2, p. 024005, 2017.
[Bibtex]
@article{Zhang:SST17,
Abstract = {An efficient three dimensional (3D) finite element method numerical model is proposed for superconducting coated conductors. The model is based on the T--A formulation and can be used to tackle 3D computational challenges for superconductors with high aspect ratios. By assuming a sheet approximation for the conductors, the model can speed up the computational process. The model has been validated by established analytical solutions. Two examples with complex geometries, which can hardly be simulated by the 2D model, are given. The model could be used to characterise and design large-scale applications using superconducting coated conductors, such as high field magnets and other electrical devices.},
Author = {H. Zhang and M. Zhang and W. Yuan},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/1361-6668/30/2/024005},
Journal = {Superconductor Science and Technology},
Number = {2},
Pages = {024005},
Title = {{An efficient 3D finite element method model based on the T--A formulation for superconducting coated conductors}},
Url = {https://doi.org/10.1088/1361-6668/30/2/024005},
Volume = {30},
Year = {2017}}
• J. Zhao, Y. Li, and Y. Gao, “3D simulation of AC loss in a twisted multi-filamentary superconducting wire,” Cryogenics, vol. 84, pp. 60-68, 2017.
[Bibtex]
@article{Zhao:Cryo17,
Abstract = {Abstract In the \{AC\} loss simulation, it is a huge challenge to model the twisted wire at the filament level, due to the complex structure as well as long-time computation consumption. In this paper, we use 3D finite-element method based on H-formulation to study the \{AC\} loss in a twisted superconducting wire. The wire is treated as a homogenous material with the anisotropic conductivity in the filament region. We quantitatively simulate the \{AC\} loss induced by the \{AC\} transport current and magnetic field profile, and the effect of the twist pitch on the \{AC\} loss. In the case of \{AC\} transport current, larger pitch length leads to higher loss, and the pitch length effect is contrary to the case of applied magnetic field. The influences of the magnetic field direction and non-uniform current distribution subjected to the strand bending are also investigated. It is observed that, the transverse magnetic field has a more significant influence on the \{AC\} loss than the longitudinal magnetic field. The non-uniform current distribution can result in a higher \{AC\} loss, compared to a corresponding uniform current distribution. },
Author = {J. Zhao and Y. Li and Y. Gao},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1016/j.cryogenics.2017.04.004},
Journal = {Cryogenics},
Pages = {60-68},
Title = {{3D simulation of AC loss in a twisted multi-filamentary superconducting wire}},
Url = {http://dx.doi.org/10.1016/j.cryogenics.2017.04.004},
Volume = {84},
Year = {2017}}
• A. Zhao, Z. Huang, B. Zhua, X. Huang, D. Hu, Z. Hong, and Z. Jin, “Fast Algorithm for Evaluating Critical Current of High-Temperature Superconducting Pancake Coil,” Journal of Superconductivity and Novel Magnetism, 2017.
[Bibtex]
@article{Zhao:JSNM17,
Abstract = {Second-generation (2G) high-temperature superconducting (HTS) tapes are now capable of carrying very high transport current and promising for a wide range of applications. The critical current of HTS coils is important for applications, such as superconducting electric machines, superconducting magnetic energy storage, and superconducting magnets. Therefore, precisely and quickly calculating critical current of HTS coils is very important for designing HTS devices. This paper provides a fast algorithm for evaluating critical current of HTS pancake coil. The fast algorithm is realized through a stationary model, which is based on finite element method (FEM) software. The stationary model means that the model is solved by stationary study instead of time-dependent study. To validate this method, a pancake HTS coil was wound and its critical current was measured. Meanwhile, an axial symmetric stationary model was built according to the geometry of the measured HTS coil. By comparing measured and calculated results, the effectiveness of the stationary model was demonstrated. Moreover, the stationary model is compared with H formulation model. The calculated results by the two models are nearly the same. However, by using stationary calculation, the stationary model can remarkably speed up the computational process. Due to the advantage of calculating speed, the stationary model can be used to characterize and design large-scale HTS applications.},
Author = {A. Zhao and Z. Huang and B. Zhua and X. Huang and D. Hu and Z. Hong and Z. Jin},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1007/s10948-017-4194-2},
Journal = {Journal of Superconductivity and Novel Magnetism},
Title = {{Fast Algorithm for Evaluating Critical Current of High-Temperature Superconducting Pancake Coil}},
Url = {https://doi.org/10.1007/s10948-017-4194-2},
Year = {2017}}
• S. Zou, V. M. R. Zermeño, A. Baskys, A. Patel, F. Grilli, and B. A. Glowacki, “Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique,” Superconductor Science and Technology (in press), vol. 30, iss. 1, p. 014010, 2017.
[Bibtex]
@article{Zou:SST17,
Author = {Shengnan Zou and V. M R Zerme{\~n}o and A. Baskys and A. Patel and F. Grilli and B. A. Glowacki},
Date-Modified = {2019-10-15 14:45:15 +0200},
Doi = {10.1088/0953-2048/30/1/014010},
Journal = {Superconductor Science and Technology (in press)},
Number = {1},
Pages = {014010},
Title = {{Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique}},
Url = {https://doi.org/10.1088/0953-2048/30/1/014010},
Volume = {30},
Year = {2017}}`

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• 7th International Workshop on Numerical Modelling of HTS.