Study Of Soft And Hard Magnetic Moments Of Targets Based On Geomagnetic Total Field Arrays

The earth has a natural magnetic field,which produces magnetic anomalies when the magnetic field of a magnetic target is superimposed on the geomagnetic field.The magnetic anomaly detection technique uses a magnetometer to detect the magnetic anomalies produced by a magnetic target within the geomagnetic field,and the magnetic anomalies are obtained by inversion.Techniques for magnetic moment information and position information of magnetic targets.The magnetic moment of a magnetic target is generally composed of an inductive moment and an intrinsic moment,which is also known as a soft moment and refers to a material that does not have spontaneous magnetism.A certain magnetic moment is created in an external magnetic field.The inherent magnetic moment,also known as the hard magnetic moment,is produced by the magnetic material in the target.With the continuous development of science and technology,the technical difficulties limiting the calculation of soft and hard magnetic moments have been overcome one by one.When using magnetic detection technology to detect magnetic targets,according to the different measurement methods and measurement information,magnetometers are divided into vector magnetometers and Total field magnetometer.Total field magnetometers are widely used in motion detection environments such as aviation and marine magnetometry.Among the various applications of magnetic detection,the magnetic study and measurement of the magnetometer carrier platform is the basis and premise of magnetic detection work.After acquiring the inherent and induced magnetic moments of the carrier platform,the demagnetization process can be carried out to effectively reduce the magnetic detection of the carrier platform.Error due to self-magnetic interference.However,an accurate measurement of the magnetic moment must be carried out in a zero or controlled magnetic field.In the absence of large magnetic devices,the magnetic anomaly model of the general field of the earth's magnetism is developed based on the magnetic dipole model.The method of the effect of geomagnetic field variation with time and space is proposed to solve the target soft and hard magnetic moments using genetic algorithm on geomagnetic total field.In the selection of magnetometer,the basic principles of fluxgate magnetometer,superconducting quantum magnetometer and optical pump magnetometer were analyzed.Optical pump magnetometer has high precision,low noise,large range,anti-interference,no zero drift,continuous measurement,attitude without strict calibration.and other advantages,so the optical pump magnetometer was chosen as the experimental magnetometer.In terms of optimization algorithm,the principles of simulated annealing algorithm,genetic algorithm and particle swarm algorithm were analyzed.The genetic algorithm can effectively solve the angle and radian description problem,fast search speed,high efficiency,and can jump out of the local optimal solution.Therefore,the genetic algorithm was chosen as the solution algorithm.It is proposed to use a magnetometer array in the geomagnetic field for magnetic moment measurement and to calculate the induced and intrinsic magnetic moment information of the target.The soft and hard magnetic moments of a magnetic target with zero inductive moment and a general magnetic target were simulated successively by using python programming.After that,genetic algorithm was used to solve the target magnetic moment and compare the analysis results.Afterwards,a larger ambient noise was added to simulate and calculate the analysis results again.The feasibility of the optical pump magnetometer triangle array to calculate the soft and hard magnetic moments of the magnetic target was initially verified.Then the experiments were carried out in Harbin along the Songhua River to design the soft and hard magnetic moment experiments of the optical pump magnetometer triangle array on the magnetic target.Magnets and automobiles were used to perform experiments to calculate hard and soft magnetic moments,and the experiments were repeated for automobiles.The comparative analysis finally verified the feasibility of the optical pump magnetometer array to calculate the inherent and induced magnetic moments of the magnetic target for the subsequent research and the application of magnetic moment measurement technology provides a reference.