A numerical model to introduce students to AC loss calculation in superconductors

Grilli, Francesco; Rizzo, Enrico

doi:10.1088/1361-6404/ab90dc

Cited by 6 publications

(5 citation statements)

References 18 publications

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“…Apart from the aforementioned numerical methods, FEM is currently the most popular tool for HTS modelling. Such models generally utilize commercial software to implement Maxwell's equations and the E-J power law or other constitutive laws for HTS modelling [53][54][55][56]. The general forms of the implemented Maxwell's equations can be classified as the A-V formulation [57][58][59][60][61], the T-Ω formulation [59,[62][63][64][65], the H-formulation [66][67][68][69][70][71], the mixed T-A formulation [72][73][74], the mixed H-A formulation [75][76][77], and the mixed H-φ formulation [78][79][80].…”

Section: Introductionmentioning

confidence: 99%

“…The key concept was to define a flux flow resistivity such that the relevant power law is 1/n rather than n to speed up the computation and obtain stable solutions. Other similar approaches were later employed by Gömöry et al in 2012 and Grilli et al in 2020 [54] [55].…”

Section: Introductionmentioning

confidence: 99%

“…[53][54][55]. The general forms of the implemented Maxwell"s equations can be classified as theA-V formulation [56][57][58][59][60], the T-Ω formulation [58][61][62][63][64], the H-formulation[65][66][67][68][69][70], the mixed T-A formulation [71][72][73], the mixed H-A formulation [74][75][76], and the mixed H-φ formulation [77][78][79].…”

mentioning

confidence: 99%

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Fully-staggered-array bulk Re-Ba-Cu-O short-period undulator: large-scale 3D electromagnetic modelling and design optimization using A-V and H-formulation methods

Zhang

Ainslie

Calvi

et al. 2021

Supercond. Sci. Technol.

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The development of a new hard x-ray beamline I-TOMCAT equipped with a 1 m long short-period bulk high-temperature superconductor undulator (BHTSU) has been scheduled for the upgrade of the Swiss Light Source at the Paul Scherrer Institute. The very hard x-ray source generated by the BHTSU will increase the brilliance at the beamline by over one order of magnitude in comparison to other state-of-the-art undulator technologies and allow experiments to be carried out with photon energies in excess of 60 keV. One of the key challenges for designing a 1 m long (100 periods) BHTSU is the large-scale simulation of the magnetization currents inside 200 staggered-array bulk superconductors. A feasible approach to simplify the electromagnetic model is to retain five periods from both ends of the 1 m long BHTSU, reducing the number of degrees of freedom to the scale of millions. In this paper, the theory of the recently-proposed 2D A-V formulation-based backward computation method is extended to calculate the critical state magnetization currents in the ten-period staggered-array BHTSU in 3D. The simulation results of the magnetization currents and the associated undulator field along the electron beam axis are compared with the well-known 3D H-formulation and the highly efficient 3D H-φ formulation method, all methods showing excellent agreement with each other as well as with experimental results. The mixed H-φ formulation avoids computing the eddy currents in the air subdomain and is significantly faster than the full H-formulation method, but is slower in comparison to the A-V formulation-based backward computation. Finally, the fastest and the most efficient A-V formulation, implemented in ANSYS 2020R1 Academic, is

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fully-staggered-array bulk Re-Ba-Cu-O short-period undulator: large-scale 3D electromagnetic modelling and design optimization using A-V and H-formulation methods

Zhang

Ainslie

Calvi

et al. 2021

Supercond. Sci. Technol.

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“…the superconducting state, flux creep, flux flow and the ohmic resistive state. Therefore, understanding the wide range E-J characteristic extended to the overcritical current region is of particular interest for HTS modellers even though the original E-J power law, the critical state model or its approximations, for example the Campbell model or other models based on artificial E-J constitutive laws, often give reasonable AC losses or other magnetization results [13][14][15][16][17]. Recently, Riva et al characterized the ReBCO CCs in the overcritical current regime by combining fast pulsed current measurements and finite element analysis (FEA) and introduced an eta-beta ρ ηβ (I, T) constitutive law at 77-90 K in self-field conditions [18,19].…”

mentioning

confidence: 99%

Understanding the current–voltage characteristic in high-temperature superconducting wires and bulks is of continuing interest to the modelling community

Zhang¹

2022

Supercond. Sci. Technol.

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“…In this article we consider only resistive SFCL 5. An introduction to the topic of AC losses in superconductor, which includes a numerical model implemented in an open-source finite-element program, can be found in[7].…”

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confidence: 99%

Superconductors for power applications: an executable and web application to learn about resistive fault current limiters

2021

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High-temperature superconductors (HTS) can be superconducting in liquid nitrogen (77 K) at atmospheric pressure, which holds immense promises for our future such as nuclear fusion, compact medical devices and efficient power applications. In a power system, high short-circuit currents can exceed the operational current by more than ten times, putting many parts of the system at risk. Superconducting fault current limiters (SFCLs) can limit the prospective fault current without disconnecting the power system, and are thus becoming increasingly attractive for future grids. With a growing interest in modeling and commercializing SFCL, the question of how to teach and to explain their operation to students has arisen. In order to help students visualize the potential use and benefits of an SFCL, we created an executable and a web application using COMSOL Multiphysics. This executable allows students to investigate the electro-thermal response of a resistive SFCL. The executable solves a 1D electro-thermal model of the SFCL under AC fault conditions, evaluating important figures of merit such as the limited current, the prospective current and the maximum temperature reached within the tape. Finally, the geometrical parameters as well as the superconducting properties of the device can be modified. The importance of the amount of silver stabilizer necessary to protect the device from over-heating occurring during a fault current can be investigated. In addition, the effects of having a sharp nonlinear transition from the superconducting to the normal state (intrinsic property of the superconductor) to obtain a current limitation can be explored. The executable allows the users to learn about the benefits of superconductors in real-life applications, without the prerequisite of extensive modeling or experimental setup. The executable can be downloaded from the HTS modeling website and run on the most commonly used operating systems.

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A numerical model to introduce students to AC loss calculation in superconductors

Cited by 6 publications

References 18 publications

Fully-staggered-array bulk Re-Ba-Cu-O short-period undulator: large-scale 3D electromagnetic modelling and design optimization using A-V and H-formulation methods

Fully-staggered-array bulk Re-Ba-Cu-O short-period undulator: large-scale 3D electromagnetic modelling and design optimization using A-V and H-formulation methods

Understanding the current–voltage characteristic in high-temperature superconducting wires and bulks is of continuing interest to the modelling community

Superconductors for power applications: an executable and web application to learn about resistive fault current limiters

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