Time-Resolved Characteristics Of Electrolyte Cathode Pulse Plasma Discharge

The content of excessive metal in water may cause great troubles.It will not only damage the environment but also affect the function of the human body.With the water pollution getting worse and worse,the detection of metal elements in water was noticed by more and more people.As an emerging water metal detection technology,the technology of liquid electrode atmospheric pressure discharge emission spectrometry combined the advantages of plasma discharge technology and spectrum detection technology.It has attracted a lot of scholars at home and abroad.In this thesis,the pulsed Electrolyte Cathode Atmospheric Discharge?pulsed-ECAD?spectrum detection system was used to collect the time-resolved spectra of the elements during the discharge cycle,and the characteristic parameters of the generated plasma were also studied.The spectral acquisition system used in this paper was based on the original discharge device in the laboratory.It was an improved pulse discharge spectrum detection system.The time-resolved spectrum of the element discharge cycle can be acquired after combining the pulse trigger circuit.First,the current and voltage characteristics of the system discharge cycle were studied.Then the time-resolved spectra of metal elements?Li,Na,K,Rb,Sr,and Mg?and molecular species emissions originating from the water and air?O,H?,H?,N₂,and OH?were also studied.In addition,using the time-resolved spectral intensities obtained from the collected elements,plasma characteristic parameters including rotation temperature,ionization temperature,electron number density,and degree of ionization of the pulsed-ECAD system were analyzed.Finally,the detection of metallic elements in actual mixed samples was examined by the pulsed-ECAD system.First,the influence of experimental parameters including frequency,flow rate and pole spacing on the spectral signal were analyzed.Quantitative analyses including self-absorption effects and matrix effects were alsodescribed.Afterwards,matrix effects on the time-resolved spectra of spectroscopic signals of metallic elements in the pulsed-ECAD discharge system were investigated.Finally,a standard curve method was used to quantitatively analyze the metal elements?Na,K,and Mg?in the actual mixed solution,and the detection limits of the three elements were obtained.Compared with the commonly used spectral analysis methods,the time-resolved spectra used in this thesis have a strong advantage for the analysis of the plasma transient process.By analyzing the time-resolved spectrum,a deeper understanding of the plasma source can be obtained,which make the time-resolved spectrum to be an important auxiliary tool for studying the mechanism of plasma generation.