Study On Magnetic Field System Of Nuclear Magnetic Resonance Gyroscope

Nuclear magnetic resonance gyroscope,which can be abbreviated as NMRG,has flourished since 1970 s.NMRG is not affected by mechanical damping.It can be characterized by high precision and miniaturization.In a word,NMRG is the future direction of development for gyroscope.The thesis is bound up with the solid work of my research group on analysis of NMRG principle and structure.Atomic Larmor precession is the core of NMRG principle.The atom of precession can be regarded as rotor of NMRG.We can measure the frequency of atom precession by Farady optical rotation detection,and then calculate the angle rate of gyroscope.NMRG is composed of the following parts: atomic cell with alkali metal clouds,noble gas and buff gas,optical pump device,RF magnetic field generating device and photoelectric detection device.The thesis is mainly concerned with RF magnetic generating device and magnetic field driven coil.The feedback control system is for dealing with the problem of measurement and calibration.Because the system is sensitive to remanence,we should compensate the magnetic field migration by comparing the Larmor frequency of two noble gas.In practice,we will use the DC component to compensate the remanence.Magnetic field generating device depends on the DDS(direct digital synthesizer)chip AD9852.With the help of MCU,we can control the DDS chip by chip control word.The output waveform of DDS can be used to driven the magnetic field coil through conditioning circuit.As we know,there is trend of miniaturization of magnetic field coils.Our research group design a novel structure,which is Braunbeck coil,to generate uniform magnetic field.The Braunbeck coil consists of four coil,which the radius and the distance between four coils has been adjusted ingeniously to get larger magnetic field uniform zone.The order of remainder term is larger so that the deviation rate of the structure shrinks sharply.Through theoretical calculation,software simulation and practical experiments,our research group has proven that the Braunbeck is able to meet the requirements for precision magnetic field excitationThe magnetic field driving circuit and novel Braunbeck coil in the issue is benefit to the prototype trial production and miniaturization.