Magnetic-field modeling with surface currents: Implementation and usage of bfieldtools

TL;DR

bfieldtools is an open-source Python package for magneto-quasistatic calculations using surface current densities, enabling practical coil design and magnetic field modeling with a user-friendly, well-documented tool.

Contribution

It introduces a general, Python-based implementation of surface current modeling with a stream-function approach, filling a gap in accessible, versatile software for magnetic field calculations.

Findings

Efficient Python implementation with extensive vectorization.

Demonstrated application in coil design.

Accessible tool for practical magnetic field modeling.

Abstract

We present a novel open-source Python software package, bfieldtools, for magneto-quasistatic calculations with current densities on surfaces of arbitrary shape. The core functionality of the software relies on a stream-function representation of surface-current density and its discretization on a triangle mesh. Although this stream-function technique is well-known in certain fields, to date the related software implementations have not been published or have been limited to specific applications. With bfieldtools, we aimed to produce a general, easy-to-use and well-documented open-source software. The software package is written purely in Python; instead of explicitly using lower-level languages, we address computational bottlenecks through extensive vectorization and use of the NumPy library. The package enables easy deployment, rapid code development and facilitates application of the software to practical problems. In this paper, we describe the software package and give an extensive demonstration of its use with an emphasis on one of its main applications -- coil design.