Design And Implementation Of 1Hz Electrochemical Seismometer

As a key unit of seismic exploration instruments,seismometers are widely used in seismic exploration field.At present,seismic exploration is gradually developing to deeper exploration depths,so the low frequency performance requirements of seismometers are also increasing.But now the low-frequency seismometers most dependent on imports,and their mass and volume are large,is not conducive to large-scale seismic exploration work.Therefore,it is very necessary to design a low-frequency seismometer suitable for deep seismic exploration.Compared with traditional moving-coil seismometers,electrochemical seismometers are liquid electrochemical as the inertial mass,and combine electrochemical and mechanical working mechanisms.It has the advantages of low natural frequency,high sensitivity,and low noise.Therefore,it has gradually attracted attention.At present,the low-frequency cut-off frequency of the existing electrochemical geophone reaction chamber of Jilin University is 10 Hz,which cannot detect low-frequency signals and the sensitivity is not very flat.Based on the existing electrochemical seismometers,this article studies and simulates the working principle of the seismometers,optimizes the structural parameters of the electrochemical seismometer's reaction chamber,designs the signal processing system,and designs a small size and light weight 1Hz electrochemical seismometer,and performance test of the developed seismometer.In this article,starting from the structure of the electrochemical seismometer,make an intensive study of the electrochemical working mechanism.And the transfer function of the seismometer cavity is deduced to provide a theoretical model for the optimization of the seismometer reaction cavity.Secondly,the finite element software COMSOL Multi-physics is used to establish the seismometer three-dimensional finite element model,coupled with the fluid field,electrochemical field and solid field,and setting the relevant parameters.The transfer function of mechanical part and electrochemical part is simulated by COMSOL.Simulate and analyze the influence of various structural parameters on the output characteristics of the seismometer,including the slope of the channel,the length of the channel,the height of the electrode and other structural parameters.Then the relevant structural parameters were optimized and the mechanical structure of the seismometer reaction cavity was established.Thirdly,the design scheme of analog conditioning circuit is proposed,and the circuit design of each module is completed,including the power supply circuit,the current-voltage conversion circuit,the amplifier circuit,the feedback circuit,coil driving circuitry and the filter circuit.Finally,this article elaborate the principle of frequency response self-testing and the specific testing steps based.The frequency characteristics of the electrochemistry seismometer prototype before and after accessing analog conditioning circuit are tested respectively.According to the experimental data,the amplitude-frequency characteristic curves of the open loop and closed loop of the seismometer prototype are plotted respectively.Through comparative analysis,the results show that the low-frequency cutoff frequency of the prototype is 1Hz,and the sensitivity reaches 350V/m/s,and the weight is only 150 g,reaching the design goal.