Quench Transient Simulation in a Self-Protected Magnet with a 3D Finite-Difference Scheme

Ravaioli, Emmanuele; Arnegaard, Ola Tranum; Verweij, Arjan; Woźniak, Mariusz

doi:10.1109/tasc.2022.3162798

Cited by 6 publications

(3 citation statements)

References 28 publications

(11 reference statements)

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“…In this case, LEDET linearly scales the winding magnetic field with the magnet current to calculate the field-change-dependent IFCL. The effect of the IFCL on magnet inductance is not accounted for in LEDET in 3D [27]. In this case, the discharge I(t) is exponential, with time constant τ=L/R proportional to total circuit inductance L and inversely proportional to the total circuit resistance R. Figure 4 also shows the first 4 iterations of the cosimulation, after which the results meet the convergence criterion.…”

Section: Resultsmentioning

confidence: 99%

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Quench Co-Simulation of Canted Cos-Theta Magnets

Wozniak,

Schnaubelt,

Dular

et al. 2024

IEEE Trans. Appl. Supercond.

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Canted Cos-Theta (CCT) magnets can use conducting formers in which eddy currents are induced during current change. This is relevant during magnet ramping or discharging after a quench, particularly when using energy extraction. CCT magnets provide substantial flexibility in terms of generating the required field shape, including the combined function field in a curved bore. However, this flexibility results in magnet geometry that often requires three-dimensional (3D) quench simulations. We propose a cooperative simulation (cosimulation) developed at CERN as part of the STEAM framework with finite element (FiQuS) and finite difference (LEDET) tools. It allows for a 3D quench simulation of a CCT magnet with great geometrical detail while maintaining reasonable computational cost. FiQuS simulates the transient electromagnetics of the entire magnet and the transient thermal behavior of the formers. The thin 3D insulation layers between the coil windings and formers are collapsed into two-dimensional surfaces, thus considerably reducing the meshing complexity and solution time. LEDET is used for 3D simulation of a quench transient, including heat diffusion in the windings, ohmic loss, and inter-filament coupling loss. Using the finite difference tool for resolving temperatures in coil windings with many turns greatly improves the simulation efficiency. In the co-simulation communication, data exchange, and convergence is controlled and achieved programmatically. A complete numerical approach is proposed, and the CCT magnet simulation results are presented and discussed.

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Section: Resultsmentioning

confidence: 99%

“…LEDET is coded in MATLAB [26] with a semi-implicit transient thermal solver that accounts for 3D heat diffusion along and between the windings as well as Joule and IFCL losses [27]. LEDET has been used for quench simulations of CCT magnets without formers [14].…”

Section: B Finite Difference Toolmentioning

confidence: 99%

Quench Co-Simulation of Canted Cos-Theta Magnets

Wozniak,

Schnaubelt,

Dular

et al. 2024

IEEE Trans. Appl. Supercond.

Self Cite

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“…LEDET is coded in MATLAB [25] with a semi-implicit transient thermal solver that accounts for 3D heat diffusion along and between the windings as well as Joule and Inter-Filament Coupling Loss (IFCL) [8,9].…”

Section: B Finite Difference Toolmentioning

confidence: 99%

Quench Protection of Fusillo Subscale Curved CCT Magnet

Wozniak,

Haziot,

Mangiarotti

et al. 2024

IEEE Trans. Appl. Supercond.

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The Fusillo project at CERN aims to design and build a demonstrator magnet with multi-harmonic corrected fields in a 90° curved CCT magnet. In the first stage, a subscale magnet is built with 30° bending, about 1/30 of the demonstrator conductor length, and increased current to reach coil stresses equivalent to the demonstrator. The subscale magnet enables qualification of the technology developments, fabrication methods, winding and assembly procedures, and magnetic and quench protection design and measurement setups. The subscale magnet comprises two tilted solenoids with an opposite inclination on curved aluminium formers. Each solenoid has two channel turns with 70 Nb-Ti/Cu wires. The magnet is protected by an active quench detection with energy extraction (EE). EE causes current decay, which induces eddy currents in the formers. As a result, the differential inductance of the magnet is reduced, and the formers heat up, with the potential to strongly influence the quench behaviour of the windings. Simulation of the eddy currents and heat propagation in the formers with simultaneous quench propagation in the magnet windings requires a three-dimensional (3D) simulation.A cooperative simulation approach has been developed to simulate transients in this magnet. It involves two software tools developed at CERN as part of the STEAM framework: a finite element-based tool called FiQuS and a finite difference-based tool called LEDET. FiQuS calculates eddy currents in the formers and the temperature of the formers, whereas LEDET calculates windings' temperature, current and voltage. This approach enables a 3D quench simulation with great geometrical detail while maintaining reasonable computational cost.The simulation results are compared to measurement results from the forced EE. The agreement between the measurements and simulations is presented, and the key factors that affect magnet quench behaviour are identified.

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A novel and fast electromagnetic and electrothermal software for quench analysis of high field magnets

Dadhich,

Fazilleau,

Pardo

2024

Supercond. Sci. Technol.

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High-ﬁeld superconducting REBCO magnets contain several coils with many turns. For these magnets, electro-thermal quench is an issue that magnet designers need to take into account. Thus, there is a need for a fast and accurate software to numerically model the overall performance of full-scale magnets. High temperature superconductors can be modeled using diﬀerent techniques for electro-magnetic and thermal (ﬁnite element method) analysis. However, it takes a lot of time to model the electro-magnetic and electro-thermal behavior of superconductors simultaneously, especially for non-insulated or metal-insulated coils. In addition, most of the available methods ignore screening currents, which are an important feature of REBCO magnets. We have developed a novel software programmed in C++, which performs coupled electro-magnetic and electro-thermal analysis using variational methods based on Minimum Electro-Magnetic Entropy Production (MEMEP) and Finite Diﬀerence, respectively. The developed software, which takes screening currents into account, is applied to axi-symmetric fullscale magnets of more than 32 T ﬁeld strength under the SuperEMFL project for thermal quench reliability during standard operation. We show that the magnets incorporating non-insulated coils are more reliable against quench than the metal insulated coils. Also, realistic cooling conditions at boundaries is essential for such simulations. The model developed can be used for a quick and complete electro-magnetic and electro-thermal analysis of superconducting high ﬁeld magnets.

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Quench Transient Simulation in a Self-Protected Magnet with a 3D Finite-Difference Scheme

Cited by 6 publications

References 28 publications

Quench Co-Simulation of Canted Cos-Theta Magnets

Quench Co-Simulation of Canted Cos-Theta Magnets

Quench Protection of Fusillo Subscale Curved CCT Magnet

A novel and fast electromagnetic and electrothermal software for quench analysis of high field magnets

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