Design Aspects for a High-Precision Active Magnetic Bearing System

Vacuum Magnetic Birefringence (VMB) is a subtle quantum electrodynamical effect predicted to induce a minute anisotropy in the vacuum refractive index in the presence of strong magnetic fields. Detecting this phenomenon requires highly sensitive polarimetric measurements under minimal vibrational disturbance. This paper presents the design and analysis of a high-precision active magnetic bearing (AMB) system intended to enable stable and low-vibration rotation of a permanent Halbach magnet for use in next-generation VMB experiments. The paper identifies the dominant sources of mechanical vibrations in active magnetic bearing (AMB) systems. A dedicated magnetic bearing arrangement is proposed, consisting of actively controlled radial and axial bearings. The use of Bode's sensitivity integral highlights fundamental performance trade-offs in the control system and justifies the decision to implement active axial stabilization. A radial magnetic bearing design is shown and the number of coil windings is derived using an analytical design metric. Closed-loop simulations are used to evaluate the influence of ADC resolution for current and position sensing on control performance. The results demonstrate that higher ADC resolution significantly reduces RMS values of position and current, providing quantitative guidance for component specification.