Study on Relaxation Characteristics of a Miniaturized ³He Magnetometer Based on Spin-Exchange Optical Pumping Technology

High-field Nuclear Magnetic Resonance (NMR) technology plays an important role in electric grid current monitoring and strong magnetic field measurements, particularly in high-precision magnetic field detection and electric grid state assessment. This study designs and constructs a high-precision strong magnetic field measurement system that precisely controls the nuclear spin rotation angle, ensuring efficient polarization and accurate measurement of ^3He in high-field environments. A high-power laser is used to optically pump Rb atoms, exciting their spin polarization, and the spin exchange between Rb and Cs atoms transfers the polarization to Cs, ultimately achieving efficient polarization of ^3He. In the experiment, a mixture of Rb and Cs metals is used, with a Rb-to-Cs volume ratio of 1:5, and the study is conducted in a high-pressure ^3He gas environment. The results show that under 3 atm conditions, the transverse relaxation time (T2) of ^3He reaches 1 second, indicating that the ^3He sample demonstrates excellent stability and sensitivity in strong magnetic field environments. This study provides the theoretical basis for the design and application of miniaturized magnetometers in high magnetic fields, suggesting that this technology has broad application prospects in electric grid current monitoring, strong magnetic field measurements, and related fields.