Numerical analysis of the screening current-induced magnetic field in the HTS insert dipole magnet Feather-M2.1-2

Abstract

Screening currents are field-induced dynamic phenomena which occur in superconducting materials, leading to persistent magnetization. Such currents are of importance in ReBCO tapes, where the large size of the superconducting filaments gives rise to strong magnetization phenomena. In consequence, superconducting accelerator magnets based on ReBCO tapes might experience a relevant degradation of the magnetic field quality in the magnet aperture, eventually leading to particle beam instabilities. Thus, persistent magnetization phenomena need to be accurately evaluated. In this paper, the 2D finite element model of the Feather-M2.1-2 magnet is presented. The model is used to analyze the influence of the screening current-induced magnetic field on the field quality in the magnet aperture. The model relies on a coupled field formulation for eddy current problems in time-domain. The formulation is introduced and verified against theoretical references. Then, the numerical model of the Feather-M2.1-2 magnet is detailed, highlighting the key assumptions and simplifications. The numerical results are discussed and validated with available magnetic measurements. A satisfactory agreement is found, showing the capability of the numerical tool in providing accurate analysis of the dynamic behavior of the Feather-M2.1-2 magnet.

Review and prospects of world-wide superconducting undulator development for synchrotrons and FELs

“…Unlike multi-filamentary twisted NbTi and Nb 3 Sn conductors whose magnetization effects are minimized, the transport current in a ReBCO coated conductor is not distributed evenly, for example, during charging a single ReBCO tape slowly the applied transport current always want to shield the tape to reserve the initial zero field as much as possible and thus flows along the edge of the ReBCO tape. This screening current induced field (SCIF) effect has been widely studied in ReBCO coils in NMR and accelerator magnets [192,193], however, not yet considered in ReBCO coils based undulator in which the SCIF effect can be much more severe due to the much smaller magnetic gap/bore. With regards to ReBCO bulk superconductor, there are also concerns for its application in staggered-array BHTSU, like the J c variation between individual ReBCO bulks and its brittle ceramic-like property, but these could be overcome by field tunings and pre-stressing techniques.…”

A prediction method for the screening current induced field in HTS magnets based on time series models

“…The advantage of this method is its accuracy, which allows it to establish the specific magnet parameters based on experimental conditions. The finite element simulation can reflect the SCIF in the HTS magnets and provide a quantification of the dynamic distribution of the screening currents [20][21][22]. Finite element method can introduce other physical fields easily and construct electromagneticmechanical superconducting models under an ultra-high magnetic field [23,24].…”

Magnetic Field Drifts of Small HTS Dipole Magnet Under Repeated Excitation

“…Furthermore, they are capable of generating extremely high magnetic fields. However, coated conductors are strongly magnetized due to their tape shape, therefore, shielding-current-induced fields (SCIFs) complicate behaviors of magnetic fields generated using coils wound with coated conductors [6][7][8][9].…”

“…accelerator used in high-energy physics [2,8]. There haven't been any experimental studies on the extremely complex influence of SCIFs on the field quality of magnets using coils wound with coated conductors, operated under aforementioned conditions; and only a few studies have been conducted using numerical analyses [7].…”