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arXiv · 2007.08963

A general method for computing thermal magnetic noise arising from thin conducting objects

Joonas Iivanainen·Antti J. Mäkinen·Rasmus Zetter·Koos C. J. Zevenhoven·Risto J. Ilmoniemi·Lauri Parkkonen
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Abstract

Thermal motion of charge carriers in a conducting object causes magnetic field noise that interferes with sensitive measurements nearby the conductor. In this paper, we describe a method to compute the spectral properties of the thermal magnetic noise from arbitrarily-shaped thin conducting objects. We model divergence-free currents on a conducting surface using a stream function and calculate the magnetically independent noise-current modes in the quasi-static regime. We obtain the power spectral density of the thermal magnetic noise as well as its spatial correlations and frequency dependence. We describe a numerical implementation of the method; we model the conducting surface using a triangle mesh and discretize the stream function. The numerical magnetic noise computation agrees with analytical formulas. We provide the implementation as a part of the free and open-source software package bfieldtools.

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Joonas Iivanainen, Antti J. Mäkinen, Rasmus Zetter, Koos C. J. Zevenhoven, Risto J. Ilmoniemi, Lauri Parkkonen. 2020-07-17. A general method for computing thermal magnetic noise arising from thin conducting objects. https://doi.org/10.1063/5.0050371

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