Research on the Performance Analysis andPrecise Measurement of High-Performance Magnetic Shielding.

近年来，超低磁场研究的实验论证达到了令人瞩目的水平。随着磁场低于0.3 nT，梯度低于0.1 nT/m， fT稳定性为数百秒，这些发展将带来各种新的研究机会，对于在各种研究领域实现更高水平的精度至关重要，包括基础和应用物理学，地球物理学，生物医学，安全和空间应用。步入式磁屏蔽室（msr），如德国物理技术研究所（PTB）的用户设施BMSR-2，已经展示了大规模高质量环境的可行性。十年后，德国工业大学（TUM）的实验设施已经为屏蔽性能设定了新的标准。随着基础物理建模的不断改进，最近哈尔滨工业大学（HIT）和TUM进一步改进的实验可以证明进一步的进展，指出需要这些现有机构的结构化和跨国联合活动，以在适当的理论和数值理解下实现磁屏蔽的最终性能。同时开发合适的探测方法，以便能够在这个水平上进行常规测量。本课题将改进屏蔽系数的预测和测量方法，建立一种定量的计算方法来模拟屏蔽的平衡过程，以及静场在外场和内场磁化下在屏蔽内部漂移的过程。在考虑温度变化和振动等虚假效应的情况下，将分析屏蔽内非常弱场的自发磁化跳变等现象。此外，还将研究来自磁屏蔽本身的噪声。随着对屏蔽内部非常弱的场的理解的提高，基于考虑所有可能的耦合效应的优化线圈设计，将有可能增强屏蔽内部应用场的均匀性和稳定性。此外，测量信号将从阻尼的外部干扰、屏蔽的影响、线圈的目标场以及各种磁强计的相互作用中解脱出来。理论分析将在上海工业大学和哈尔滨工业大学的磁屏蔽实验中得到验证。研究结果还有助于描述和优化哈工大新建的大型强磁屏蔽设备的性能，为该领域树立新的标杆，支持基础物理实验和其他低场研究的新水平。

Experimental demonstrations in ultra-low magnetic field research has reached spectacular levels recently. With fields below 0.3 nT and gradients below 0.1 nT/m, with fT stability of hundreds of seconds, these developments will enable a variety of new research opportunities and are crucial to achieve the next level of precision in various fields of research, including fundamental and applied physics, geophysics, bio-medical, security and space applications. Walk-in magnetically shielded rooms (MSRs), like the user facility BMSR-2 at the Physikalisch-Technische Bundesanstalt (PTB), already show the feasibility of large- scale high quality environments. A decade later, the experimental facility at the Technische Universitat München (TUM) already set a new standard for shielding performance. With a continued improvement in modeling of the underlying physics, very recently an even further improved experiment of Harbin Institute of Technology (HIT) and TUM could demonstrate even further progress, pointing out the need for a structured and trans-national joint activity of these currently institutions to achieve the ultimate performance of magnetic shields with proper theoretical and numerical understanding, together with the development of suitable probing methods to be able to actually perform measurements at this level routinely. In this project, the methods to predict and measure shielding factor will be improved: a quantitative calculation method will be established to simulate the equilibration process of shields and also the static fields drift inside shields due to magnetization by external and internal fields. Phenomena like spontaneous magnetization jumps of the very weak field inside shields will be analyzed considering spurious effects like temperature changes and vibrations. Also, noise originating from magnetic shielding itself will be investigated. With improved understandings of the very weak field inside the shields, it will then be possible to enhance homogeneity and stability of applied fields inside shields, based on optimized coils design considering all possible coupling effects. Moreover, the measured signals will be disentangled from the damped external disturbances, the influences from shields, the target field from coils, and the interactions from various magnetometers. The theoretical analysis will be and demonstrated with experiments in magnetic shields in TUM and HIT. The findings also serve to characterize and optimize the performance of the new large and strong magnetic shielding facility constructed at HIT to set a new benchmark in the field, supporting the next level of fundamental physics experiments and other research at low fields.