Study On Evaluation Of Main Technical Indexes Of Proton Magnetometer

As a high-precision magnetic field measuring instrument,the proton magnetometer has been widely used in geophysical research,earthquake prediction,mineral exploration,archaeology and other fields due to its advantages of good stability,small size,easy portability,and simple operation.After decades of research,the basic functions of the proton magnetometer have stabilized and are developing towards higher performance.In order to guide the development of the proton magnetometer,it is particularly important to accurately evaluate the performance of the proton magnetometer.The proton magnetometer has many technical indicators,and the difference between the technical indicators of different magnetometers can reflect the difference between the performance of the magnetometer,so the technical indicators are an important basis for evaluating the performance of the magnetometer.However,at present,there is no unified standard for the evaluation of the technical indicators of the domestic proton magnetometer,and the related literature is very scarce,which has caused the domestic research and development personnel to be unable to accurately evaluate the performance of the proton magnetometer,which will restrict the development of the domestic proton magnetometer.Therefore,the research on the evaluation method of the main technical indicators of the proton magnetometer is of great significance.This thesis focuses on this theme and studies the evaluation methods of the main technical indicators of the proton magnetometer.The main innovations and work contents are as follows:(1)The performance of the proton sensor will have a direct impact on the performance of the magnetometer.Aiming at the problem of fast signal attenuation of JPM proton sensor,in this article,the sensor's coil structure,internal solution type,and shielding method are theoretically analyzed.Through research and software simulation,a “8” type coil with better directionality and slower signal attenuation speed is designed,and the signal attenuation time constant is 0.82 s through testing.Finally,the repeatability experiment proved that the design has good repeatability.(2)This paper theoretically studies three methods of evaluating sensitivity,direct measurement method,synchronous measurement method and gradient measurement method,and designed experiments to verify the accuracy of these three evaluation methods in field experiments.It proves that the synchronous measurement method and the gradient measurement method are suitable for sensitivity evaluation in the field environment.Using the fourth-order difference with synchronous measurement method to evaluate the sensitivity of the JPM proton magnetometer,the result is 0.039 n T@3s.(3)This paper designs the evaluation methods of the power consumption of the proton magnetometer,whether the sensor is omnidirectional and the influence of the host on the absolute accuracy,and evaluates the relevant indicators of the JPM proton magnetometer through experiments,which proves the feasibility of these evaluation methods.The experimental result is that the average test power consumption of the JPM proton magnetometer is 4.4W,and the proton sensor has good omnidirectionality.(4)In this paper,the circular Helmholtz coil is used to evaluate the measurement range and gradient tolerance of the proton magnetometer,and the resolution and cycle time index of the JPM magnetometer are evaluated through experiments.The evaluation result is that the measurement range of the JPM proton magnetometer is20000-120000 n T,the gradient tolerance is 15000 n T/m,the resolution is less than0.01 n T,and the cycle time is adjustable from 3s to 3600s.