Reserch On Currrnt Diagostic Technique Of Discharge Process In Liquid

The technology of plasma generation by liquid discharge is one of the most promising research contents to solve the energy and environment crisis in the world today due to its wide application range,low energy consumption,low environmental pollution and other advantages.As an important index to study the change of discharge,discharge current reflects the law of interaction between particles in the liquid.It is an important basis for studying the evolution process of plasma.Through circuit design,data acquisition,model verification and other ways to complete the current diagnosis in the discharge process,the specific work is as follows:(1)According to the characteristics of transient discharge current,a dual-channel current diagnosis circuit is designed to complete the I/V conversion,filtering processing and gain regulation.A high-speed data acquisition system is completed by selecting appropriate ADC08D500 ADC chip,memory chip,interface circuit chip,etc.,and current data signal acquisition is completed by FPGA control.Finally,it is uploaded to the PC for display.(2)An experimental device for direct current discharge in liquid was built and combined with the current signal diagnosis circuit,the overall current change was studied under the experimental conditions of initial conductivity of 0.15 S /m,initial temperature of 50℃,immersion depth of cathode tungsten rod of 20 cm,and area of stainless steel plate of(20cm×30cm).In order to further diagnose the discharge current,data acquisition and experimental observation of the possible factors causing the current change are carried out in different stages.(3)According to the observed experimental phenomena,a diagnostic model of discharge current in liquid was established based on the thermodynamic theory of bubble change,and the current change in discharge process was summarized as the result of the joint action of liquid resistance and bubble resistance.The effect of bubble resistance was obtained by analyzing the liquid resistance and the way of grid element division.The final current change is attributed to the temperature,conductivity,bubble radius(escape radius,heat exchange radius,collision radius)and other factors,and according to the principle of single variable Matlab simulation analysis,and get the discharge current and multi-factor influence curve relationship,and then explain the current change rule in the discharge diagnosis experiment.