旋转超导体产生的微弱伦敦磁场的探测

Detection of London Moment of Rotating Superconductor

旋转超导体会在其内部产生一均匀磁场,称为伦敦磁场。伦敦磁场的研究具有重要理论和应用价值。本文对微弱伦敦磁场的探测方法进行了初步研究,使用多层超导筒屏蔽外界环境磁场的干扰,采用超导量子干涉器件(SQUID)来读出旋转超导体产生的磁场。通过对冻结磁通产生的干扰信号的有效分离,成功地观测到了伦敦磁场信号.通过理论分析,确定了伦敦磁场探测对应屏蔽性能的要求,对提高伦敦磁场探测信噪比的措施进行了讨论。

A rotating superconductor will generate a uniform magnetic field in its interior, which is called London field. Investigation on London field has great importance on both theoretical and application aspects. A method for detecting the weak London field was investigated. The environmental magnetic field was shielded using multilayer superconducting cylinder, and the signals from the London moment was readout by a Superconducting Quantum Interference Device （SQUID）. By distinguished and separated noise signal caused by frozen flux, London field was successfully observed. Based on theoretical analysis, the properties of requirements on shielding were determined and means to improve the signal to noise ratio were discussed.