Research On Magnetic Gradient Detection Technology For Unexploded Ordnance Detection

Explosives are widely used in all levels of military activities in the globe.In wartime areas and post-war areas,the large volume of unexploded ordnance poses a significant threat to the lives of the local civilian and military population.In many years,various global forces have invested of human and financial resources in researching methods for detecting unexploded ordnance,but still encounter major technical difficulties on this subject.This paper addressed the problems of current mainstream detection of unexploded ordnance that the scope of application is not wide,and the accuracy of the UXO orientation and depth calculation is not high,and proposes to use the Superconducting Quantum Interference Device(SQUID)magnetic gradiometer to detect unexploded ordnance,which is one of the most sensitive magnetic detection devices,to detect extremely weak magnetic anomaly signals and to obtain spatial position information of the magnetic anomaly source through inversion operations.Through experimental tests and simulation calculations,proved SQUID magnetic gradiometer can detect many kinds of explosives,including weak magnetic unexploded ordnance,and the proposed inversion method can accurately obtain the orientation information of the source of magnetic anomaly of unexploded ordnance.The prototype instrument is suitable for many types of unexploded ordnance and has a high engineering application value for the accuracy of the depth calculation of buried unexploded ordnance.The main research in this paper is as follows.Described the technical background of unexploded ordnance detection,introduced the mainstream unexploded ordnance detection methods and SQUD magnetic detection research at home and abroad,the advantages and disadvantages of various methods are briefly summarized.Described the basic principles of SQUID,the basic structure and principles of SQUID magnetic gradiometer,magnetic detection data processing and inversion methods.Presented the main components and technical features of the SQUID magnetic gradiometer prototype used in the article.The theoretical feasibility of the SQUID magnetic gradiometer for unexploded ordnance detection is illustrated.Illustrated the theoretical feasibility of the SQUID magnetic gradiometer for unexploded ordnance detection.Designed experiments for indoor and outdoor magnetic gradient detection with using multiple models with and without magnetism with similar characteristics to unexploded ordnance.These experiments were used to test the validity and accuracy of the SQUID magnetic gradiometer prototype's ability to detect magnetic gradients and inversions for both magnetic and non-magnetic models.By using COMSOL,constructed simulation models suitable for unexploded ordnance detection,including background magnetic field solving domains,stratigraphic and airborne background models,and unexploded ordnance models.The UXO models include: homemade improvised bomb models,artillery bomb models,mine models and cluster bomb sub-bomb models.Multiple measurement scenarios are built using the unexploded ordnance model,the magnetic anomaly features of the model are analyzed,and the validity and accuracy of the inversion method is verified.Designed and developed a desktop application,the UXO Detection Data Visualization Management System,to address gaps in the detection project management and visualization of detection results in the SQUID Magnetic Gradient Prototype Package detection software.The application uses several open source frameworks and tools to add and view the probe project,manage the directory query of the probe project,record the probe project information,display and depth statistics of inversion results,and display the map of the probe area.