An Investigation of Magnetic Hysteresis Error in Kibble Balances

TL;DR

This paper investigates the impact of magnetic hysteresis in yoke-based magnetic circuits of Kibble balances, proposing an evaluation method and discussing ways to minimize the resulting measurement errors.

Contribution

It introduces a novel evaluation technique using minor hysteresis loops to estimate hysteresis effects in Kibble balances.

Findings

Hysteresis causes measurable errors in magnetic flux during measurements.

Measuring minor hysteresis loops can estimate hysteresis effects.

Potential optimizations can reduce hysteresis-induced errors.

Abstract

Yoke-based permanent magnetic circuits are widely used in Kibble balance experiments. In these magnetic systems, the coil current, with positive and negative signs in two steps of the weighing measurement, can cause an additional magnetic flux in the circuit and hence a magnetic field change at the coil position. The magnetic field change due to the coil current and related systematic effects have been studied with the assumption that the yoke material does not contain any magnetic hysteresis. In this paper, we present an explanation of the magnetic hysteresis error in Kibble balance measurements. An evaluation technique based on measuring yoke minor hysteresis loops is proposed to estimate the effect. The dependence of the magnetic hysteresis effect and some possible optimizations for suppressing this effect are discussed.