Development Of JPM-4 Proton Magnetometer And Evaluation Of Measurement Range Specification

Proton magnetometer is a high-precision scalar magnetometer with the advantages of relatively low manufacturing cost,good stability,easy operation,portability and work in harsh environments.At present,proton magnetometers are widely used in geophysical research,archaeological exploration,mineral exploration,magnetic permeability target detection and earthquake prediction.Proton magnetometer is developed based on the Larmor precession effect in atomic physics.The Larmor sinusoidal signal sensed by the sensor is amplified,filtered,and shaped by an analog circuit,then the digital circuit further performs a digital frequency calculation on the analog processed signal to obtain a magnetic field value.Based on the JPM-4 proton magnetometer developed by our research group,this paper analyzes and improves the defects of the current instrument software functions,and evaluates the technical specifications of the instrument,especially the measurement range specification.Firstly,this paper introduces the research significance of proton magnetometer and the research progress at home and abroad,and introduces the working principle of proton magnetometer and the system architecture of JPM-4 proton magnetometer.Then,the JPM-4 magnetometer software function has been expanded to include battery power display,mobile measurement mode and diurnal correction function.Next,for the evaluation of the magnetic measuring range specification of the JPM-4 magnetometer,it is necessary to simulate and design a small-sized uniform field solenoid.Finally,the sensitivity,resolution and magnetic measuring range of the JPM-4 magnetometer were analyzed and evaluated,and the JPM-4 magnetometer's mobile measurement mode and diurnal variable correction function were tested.The test results show that the mobile measurement mode and the diurnal variable correction software function test are normal,which can well meet the needs of the magnetometer in the application scenarios such as field measurement and target detection.In the evaluation of the magnetic measurement range,the internal magnetic field gradient of the designed and fabricated small-sized conventional field solenoid is controlled within 400nT/m,and the magnetic measuring range of the JPM-4 magnetometer is estimated to be 20000nT~120000nT.In addition,the synchronization and gradient sensitivity evaluations of JPM-4 were both 0.1nT@3s,the gradient tolerance is 7500nT/m and the resolution was 0.01 nT.