A Fast and Efficient Measurement System for Nuclear Spin Relaxation Times in Atomic Vapors

Abstract

With the rapid progress of cutting-edge research such as quantum measurement technology, nuclear magnetic resonance (NMR) gyroscopes represent a major development direction of high-precision micro-miniature gyroscopes, which have significant advantages such as high precision, small size, and low power consumption. It is meaningful to measure the relaxation times of noble-gas atoms which are crucial indicators to accurately and quickly characterize the vapor cell performance as a core component of gyroscopes. In this paper, a test platform for relaxation time is built and an automatic relaxation time test system based on free induction decay (FID) and the π pulse method is designed to accelerate the relaxation time test. Firstly, the formula of the atomic dynamic process based on the Bloch equation was deduced, a GUI (Graphical User Interface) simulation based on the derived differential equation was conducted, and the moving process of the magnetic moment was visually described. Then, the virtual instrument was used to integrate multiple test instruments into an auto-test system, and LabVIEW programming was used for control to realize the automation of the test process on the test platform. Finally, the test results in different conditions were compared. The results show that the test system is stable and reliable with excellent man–machine interaction, and the measurement efficiency was increased by about 185%, providing an effective test scheme for vapor cell performance.

Energy dissipation during collision for anti-relaxation coatings in alkali-metal vapor cells

“…The relaxation time was detected by measuring the time required for the spin vector intensity of transversely polarised nuclei to drop to 1/e of the initial value. 21) The temperature of the vapor cell was controlled by PI feedback, and precise temperature control was employed to detect the relaxation time of the cell at different temperatures. During the experiment, we accurately controlled the temperature of the coated alkali-metal vapor cell by controlling the oven temperature and the temperature control accuracy is 0.1 °C.…”