Coupling electromagnetic numerical models of HTS coils to electrical circuits: multi-scale and homogeneous methodologies using the T-A formulation

The REBCO high-temperature superconducting tape has a pronounced electromagnetic anisotropy. The critical current is strongly dependent on the value of the magnetic field, the magnetic field direction, the temperature, and the stress, and has a significant nonlinear relationship. It is also important to note that screening current effects in superconducting magnets at elevated temperatures lead to a non-uniform distribution of current densities, and thus the inductance of superconducting magnets at high-temperatures is calculated differently from that of normal magnets. This is essential for the design of superconducting energy storage magnets at high-temperatures, especially for the accurate evaluation of the inductance values. To further analyze the variation of the inductance value due to the REBCO screening current, the T-A formulation combined with the magnetic energy density is considered to evaluate the energy storage and inductance values during the excitation of the superconducting coil. The effect of excitation rate, operating temperature, and excitation current on the inductance value is analyzed based on the design of a 5T insulating superconducting coil. The mathematical relation between excitation voltage, contact resistance, and inductance in the magnetic excitation experiment is presented, and the accuracy of the calculated method is verified by comparison with simulation results.

Section: Effect Of Excitation Speed On the Inductance Of Hts Coilsupporting

confidence: 92%

Section: Calculation Of Superconducting Magnets Inductance Valuementioning

confidence: 99%

Section: Introducementioning

confidence: 98%

See 1 more Smart Citation

A method to evaluate the inductance properties of REBCO excitation process based on magnetic energy density and T–A formula

Hong

et al. 2023

“…Figure 5 illustrates the entire process. Our study demonstrated that this approach can be ten times faster compared to the original approach (modeling individual turns) without compromising accuracy [45].…”

Section: Coupled Numerical Model Of the Hts Coilmentioning

confidence: 83%

Characterization of flux pump-charging of high-temperature superconducting coils using coupled numerical models

Zhou,

Ghabeli,

Ainslie

et al. 2023

Self Cite

Flux pumps provide a promising solution for contactless charging of high-temperature superconducting (HTS) coils, eliminating the need for bulk current leadsand reducing the heat burden for the cryogenic system. Characterizing the nonlineareffects of an HTS coil charged by a flux pump and understanding the dynamics ofthe charging process is essential for promoting the practical application of flux pumps.Numerical models provide a fast and cost-effective way of achieving this. In this study,we propose a methodology for coupling HTS coil and flux pump models using anelectrical circuit, resulting in reduced computation costs. We validate the effectivenessof our approach against the experimental results of an HTS coil charged by a dynamo-type flux pump. Specifically, we obtain the voltage produced by the HTS dynamo usinga 3D model based on the minimum electromagnetic entropy production (MEMEP)method and apply this voltage to the load HTS coil using a T-A formulation finite-element method (FEM) model coupled via an electrical circuit. The simulated chargingcurrent shows good agreement with experimental observations, validating our modelingstrategy. The results demonstrate that the flux flow state in the HTS coil is theprimary factor limiting the charging performance of the HTS dynamo as the chargingcurrent approaches the coil’s critical current. Furthermore, based on the simulation,we demonstrate that, when using flux pumps, it is advisable to leave a margin betweenthe operating current and the critical current of the coil. Overall, our approach hasthe potential to be applied to HTS coils charged by any device.

“…Various existing publications have presented a method that combines the circuit, and the FEM model [46,47]. We also suggest a sequential simulation method, as shown in figure 2 Therefore, the effect of current distribution due to the radial current and the screening current on magnetic field distribution can be analyzed by this method, and it will be discussed in the next section.…”

Section: Analysis Method: a Sequential Simulation Model Consisting Of...mentioning

confidence: 99%

Investigation on nonuniform current density and shape deformation affecting the magnetic field performance of a saddle-shaped no-insulation HTS cosine–theta dipole magnet

Kim

Park

Bang

et al. 2023

In particle accelerators, high magnetic fields are desirable for discovering new particles. Dipole magnets using superconductors have played a key role in creating required field intensity and uniformity. In contrast, high temperature superconductor (HTS) dipole magnets have recently been spotlighted because of their ability to generate higher magnetic fields compared to their low temperature superconductor counterpart. Similar needs have emerged in other fields using magnets, and no-insulation (NI) technology is considered a feasible option to reach high magnetic fields by overcoming the disadvantages of HTS magnets. However, research has rarely been carried out on the utilization of NI HTS magnet technology for dipole magnets in high-field accelerators. Here we show the design, fabrication, and test results of an NI HTS dipole magnet with numerical analysis results. This paper aims to investigate the effect of nonuniform current density and undesirable shape deformation on the magnetic field distribution of a saddle-shaped NI HTS dipole magnet. The magnet is designed and constructed considering the 'constant perimeter winding' technique and tested in liquid nitrogen. The field mapping process is also performed along a designated mapping trajectory to obtain a magnetic field distribution. T-A formulation-based simulation model, named 'sequential simulation model,' is suggested to reproduce measurements and employed considering current distribution and shape deformation. As a result of quantitative analysis of the transverse direction measurement results, the magnetic field error decreased by 0.02 percent point (pp) when the nonuniform current density is considered. It decreased by 0.13 pp when the shape deformation is considered. Moreover, the critical current calculated through additional numerical analysis shows an error of up to 10%. In conclusion, the saddle-shaped NI HTS dipole magnet can produce a sufficient magnetic field level for particle accelerator research, even though the field distribution shows a uniformity of 0.37% within this study.