Round-Core-Radius-Dependent Electromagnetic Coupling of Multifilament Helical Superconducting Tapes in a Swept Magnetic Field

TL;DR

This study investigates how the electromagnetic coupling in multifilament helical superconducting tapes depends on the round core radius R, revealing that reducing R suppresses coupling and that the onset of coupling scales as R^{-2}.

Contribution

It provides a theoretical and numerical analysis of the R-dependent electromagnetic coupling in superconducting tapes under ramped magnetic fields, highlighting the flux penetration mechanism.

Findings

Electromagnetic coupling can be suppressed by reducing core radius R.

The coupling sweep rate scales as R^{-2}.

Behavior resembles flat tape response even for narrow cores.

Abstract

With the excitation and demagnetization of a magnet for magnetic resonance imaging in mind, we theoretically and numerically investigated electromagnetic coupling--especially its dependence on the round core radius $R$--of multifilament helically wound superconducting tapes under steady-state conditions in a constantly ramped magnetic field. We found that even in a rapidly ramped magnetic field, the electromagnetic coupling can be suppressed by reducing $R$ to close to the tape width. We also clarified that the coupling sweep rate at which the electromagnetic coupling starts scales as $R^{-2}$, showing that the dependence on $R$ reflects the penetration of magnetic flux from the edges of the tape. Even when the round core is as narrow as the tape width, the behavior is considered to be similar to the electromagnetic response of a flat tape rather than that of a tubular wire.