中文摘要：

磁场的高均匀性是高性能核磁共振弛豫分析仪实现短弛豫时间样品和微弱信号核磁共振（NMR）检测的基本保障.该文以0.45T双极型永磁体作为设计核心部件，在大范围磁体空间—25.4mm球空间（DSV）内，基于目标场法设计了X、Y、Z、XY、XZ、YZ、Z2共7组有源匀场线圈，根据线圈供电要求，设计了可编程恒流电源，搭建了可用于高性能核磁共振弛豫分析仪磁体的有源匀场系统，介绍了系统的基本结构、设计过程及匀场方法.实验测试结果验证了大范围磁体空间内该匀场系统的实用性.

英文摘要：

High homogeneity of the magnet field is an essential prerequisite for measuring weak signals and short spin-spin relaxation time on a nuclear magnetic resonance (NMR) analyzer. In this study, we designed active shimming coils, based on a target-field approach, for low filed NMR analyzers. Constant current source was designed according to the coil power supply. An active shimming platform used in a NMR analyzer’s 0.45 T magnet system was constructed over a large target-diameter-sphere-volume (25.4 mm DSV) of interest. The basic structure and operation principles of the system, as well as the shimming method, were introduced. The feasibility and practicality of the design was demonstrated by experimental measurements.