Tunable Superconducting Magnetic Levitation with Self-Stability

TL;DR

This paper introduces a tunable, self-stable superconducting maglev system using a flux pump, overcoming previous limitations of fixed flux pre-capturing and energy losses, enabling adjustable levitation and long-term stability.

Contribution

It presents the first experimental demonstration of a self-stable, tunable superconducting maglev system that maintains levitation without flux pre-capturing and counters force decay.

Findings

Demonstrated adjustable levitation force and height.

Achieved levitation under zero field cooling conditions.

Counteracted long-term levitation force decay.

Abstract

Magnetic levitation based on the flux pinning nature of type II superconductors has the merit of self-stability, making it appealing for applications such as high speed bearings, maglev trains, space generators, etc. However, such levitation systems physically rely on the superconductor pre-capturing magnetic flux (i.e. field cooling process) before establishing the levitation state which is nonadjustable afterwards. Moreover, practical type II superconductors in the levitation system inevitably suffer from various sources of energy losses, leading to continuous levitation force decay. These intrinsic drawbacks make superconducting maglev inflexible and impractical for long term operation. Here we propose and demonstrate a new form of superconducting maglev which is tunable and with self-stability. The maglev system uses a closed-loop type II superconducting coil to lock flux of a magnet, establishing self-stable levitation between the two objects. A flux pump is used to modulate the total magnetic flux of the coil without breaking its superconductivity, thus flexibly tuning levitation force and height meanwhile maintaining self-stability. For the first time, we experimentally demonstrate a self-stable type II superconducting maglev system which is able to: counteract long term levitation force decay, adjust levitation force and equilibrium position, and establish levitation under zero field cooling condition. These breakthroughs may bridge the gap between demonstrations and practical applications of type II superconducting maglevs.