Design And Experimental Study Of Plasma Jet Device

Since its inception,atmospheric pressure non-equilibrium plasma jet is of great interest and widely studied by researchers and has been one of the hot spots in the field of low-temperature plasma physics research and practical application.Compared with conventional low-temperature plasma discharge,free radicals,charged particles and metastable particles can be generated by plasma discharge in atmospheric pressure plasma jet.They can be transmitted to the remote area under the action of gas field and electric field,which ensures the stability of the discharge system.At the same time,the plasma generated by the discharge has no sense of electric shock and burning,and can be in direct contact with organisms,which promotes the application of plasma jet in medical treatment.It plays an important role in the inactivation of bacteria,blood coagulation and the treatment of cancer cells,because of carring a large number of free radicals and active particles.In this paper,a plasma jet-generating device is designed through simulation and experiment to study the plasma jet.The research work of this thesis includes:Firstly,using the two-dimensional axisymmetric plasma jet model,the atmospheric pressure non-equilibrium plasma jet with double ring electrode structure driven by pulse ac power is numerically simulated.Through numerical simulation,the parameters such as electron density,electron temperature,electron direct collision ionization source term and electric field intensity can be obtained in the discharge process.On the basis of this structure,the radius of the dielectric tube can be reduced or the length of the electrode can be modified to compare with it.Results show that the discharge from the first two electrodes in the middle of the high field strength area,then from the two areas to development at both ends,but the main energetic flow downstream development,and discharge in the central axis location,the strongest discharge is the tube wall along the media development,the formation of plasma jet "head" will present a "bullet" modelling.Then,the radius of the dielectric tube and the length of the electrode are modified on this basis,it is found that the evolution law of the plasma jet is roughly the same as before.The main differences are reflected in the difference in electron density and reaction rate,but some of the laws still need to be further studied.Secondly,the experiment of argon non-equilibrium plasma jet was designed and carried out under an atmospheric pressure.In the experiment,the infrared thermal imager showed that the temperature of plasma jet was close to room temperature,and there was no burning sensation when fingers were close to it.With the increase of argon gas flow rate,the breakdown voltage and circuital current will also increase.If the electrode length is reduced,the breakdown voltage will also be reduced.Appropriately reduce the diameter of the dielectric tube,the breakdown voltage will also be reduced.Thirdly,on the basis of simulation and experiment,a plasma jet array is designed,which can generate a plasma with a certain electron density distribution.In addition,the plasma layer generated by plasma jet array is used for electromagnetic wave transmission and scattering simulation.It is found that the larger the incident Angle is,the smaller the transmission coefficient will be.The higher the collision frequency is,the larger the transmission coefficient will be.The higher the frequency of electromagnetic wave is,the larger the transmission coefficient is.