Design Of JOM-3 Overhauser Magnetometer And Evaluation Of Technical Indicators

Overhauser magnetometer is a precision magnetostatic measuring instrument based on the Overhauser effect(dynamic nuclear polarization or electronic and nuclear double resonance principle),with high precision,high sensitivity,low power consumption and fast reading,etc.,are widely used in geology investigation,mineral exploration,archeology,anti-submarine,unexploded ordnance exploration,shipwreck recovery,oil and gas exploration,space exploration and other fields.The research group has independently developed two generations of Overhauser magnetometers,which are being developed a new magnetometers currently.The JOM-3 Overhauser magnetometer described in this paper is based on ARM + CPLD architecture.The paper mainly researches in the aspects of sensor design,power circuit design,RF circuit design,instrument technical index evaluation and other aspects.The main contents of the thesis are as follows:1.Understand the working principle of Overhauser magnetometer.Design and manufacture sensor that meet the performance of the instrument.The sensor uses the antiphase series differential coil structure as the low frequency receiving coil,and uses the capacitor to load the coaxial resonant cavity for RF excitation.2.A multi-functional power supply circuit is designed to provide power protection for each module of the magnetometer and to verify its function through relevant experiments.In analog part,we designed the power conversion circuit that provides power for each functional circuit,and elaborated the design idea of the polarized circuit.The RF excitation circuit is optimized and improved with single power supply and dual power amplifier output.At the same time,Direct Digital Synthesis(DDS)signal source circuit is designed to find the best RF excitation point.3.In order to in-depth study the performance and indicators of the Overhauser magnetometer,we designed experiments and discussed the factors which affecting the Overhauser magnetometer,and compared it with the Canadian GSM-19 and the laboratory-developed JOM-2 magnetometer.We also conducted field tests.The test results show that the sensitivity of Overhauser magnetometer is 0.17 n T and can accurately obtain the magnetic field value.