论文部分内容阅读
用于高分辨核磁共振仪的静磁场必须有高度的稳定性。在由电磁铁建立的静磁场中,稳定励磁的电流,最佳情况只能将磁场稳定于10~(-6)量级,且由于温度与外界磁场变化等影响,磁场的稳定度可能还更低些。通常采用磁通稳定器将磁场稳定度进一步提高。本文分析了磁通稳定器的工作原理并提出了一种较好的磁通稳定器,它由拾磁线圈、反馈线圈、低漂移放大器及有源校正网络组成闭环反馈系统。通过观察乙基苯(或乙醛)的NMR信号,确认加装磁通稳定器后可使磁场的稳定度提高二个数量级以上。
The static magnetic field used for high-resolution nuclear magnetic resonance must have a high degree of stability. In the static magnetic field established by the electromagnet, the stable excitation current can only stabilize the magnetic field at the level of 10 -6 in the best situation, and the stability of the magnetic field may be further affected by the change of the temperature and the external magnetic field Lower. Magnetic flux stabilizers are often used to further increase the stability of the magnetic field. This paper analyzes the working principle of flux stabilizer and puts forward a better flux stabilizer. It consists of a closed loop feedback system consisting of a magnetic pickup coil, a feedback coil, a low drift amplifier and an active correction network. By observing the NMR signal of ethylbenzene (or acetaldehyde), it was confirmed that the stability of the magnetic field could be increased by more than two orders of magnitude after installing the flux stabilizer.