Study On A New Method Used In Marine Electric Field Detection Based On Electro-Magnetic Conversion

Since the conflicts between China and other Asian countries around maritime rights and interests turn to be increasingly complex,marine monitoring has become increasingly prominent.As an important means of marine monitoring,marine electric field detection,especially ship electric field detection,has an extremely important application value in both military and civilian use.In this article,a new method of marine electric field detection based on electro-magnetic conversion was proposed.Researches focus on the generation and distribution of ship electric field,the circuit equivalent of electro-magnetic conversion module,noise characteristics,structure design and preparation technology have been studied systematically.A finite element model of hip electric field was established by analyzing the mechanism of ship electric field's generation.The distribution of ship electric field was analyzed,and the attenuation law of ship electric field signal in the very low frequency band was revealed.The detection range of ship electric field signal was theoretically ascertained,which laid a theoretical foundation for the marine electric field signal detection.A method of electric field measurement based on electro-magnetic conversion was proposed.Using high sensitive magnetic tunnel junction for measurement,low frequency electric signal was converted into high frequency magnetic signal,which can effectively avoid the influence of 1/f noise.Based on circuit equivalent,the signal transfer model of electro-magnetic conversion method was established and the noise of this model was analyzed.The results show that the electro-magnetic conversion module can be equivalent to the traditional low noise preamplifier,and can reduce the ultra-low frequency background noise of the detection system effectively.The effects of electro-magnetic conversion micro-system's structure parameters on the magnetic field strength are studied.The structure of the electro-magnetic conversion module optimized for the underwater target detection is designed.The simulation results show that the magnetic field strength can be further increased by the double C wedge-shaped magnetic focusing structure.And the micro-mechanical structure of the electro-magnetic conversion module was fabricated.Influences of structure parameters on the performance of electro-magnetic conversion structure were analyzed based on electro-magnetic finite element method.A micro-electro-magnetic conversion structure based on double C wedge-shaped magnetic concentrator for ship electric field detection was designed.The relationship between the thickness of Cr,Cu,SiO₂ films in electro-magnetic multilayered film structure and their stress state was established by experimental analysis method.Optimization design of the structure was also carried out.The micro-machining process of electro-magnetic conversion structure was established,and the sample preparation was realized.The performance test system for electro-magnetic conversion structure was built and used for equivalent input resistance,transfer resistance and equivalent input noise testing.The results show that equivalent input noise of the electro-magnetic conversion module at 1Hz was 0.67nV/?Hz,validating the effectiveness of the electro-magnetic conversion method in reducing ultra-low frequency background noise.