The influences of cell’s temperature characteristic on the performance of nuclear magnetic resonance gyroscope

Systematic errors resulting from differential alkali field, electric quadrupole interactions are the keys to the long-term stability of the nuclear magnetic resonance (NMR) gyros. In this paper, we review the basic theory governing spin-exchange pumped NMR gyros, and a simple model analyzing the influences of vapor cell’s temperature characteristics on the bias and noise is presented. We discuss how temperature characteristics (temperature drift and temperature gradient) limit the bias stability theoretically, and methods to minimize them. To validate the theoretical analysis, a NMR gyro with dual species operation is set up. The precession signals for the two isotopes are phase-closed to the drive waveforms for the nuclear magnetic resonance by adjusting the drive frequency. The result shows that temperature drift may introduce uncontrolled systematic errors, which are indistinguishable from actual rotations. Imperfect temperature stabilization set the ultimate limit of precision for the NMR gyro. The low frequency magnetic noise can be suppressed by static field stabilization control. However, the phase delay induced by Rb magnetometer and the differential alkali field are also the main source of the bias. Additionally, imperfect measurement of the NMR phase introduced by temperature gradient may be a significant contributor of noise.