Study On Formation And Application Of Atmospheric Pressure Air Low Temperature Plasma Jet Based On DC Discharge

In recent years,with the development of research,the atmospheric pressure low temperature plasma jet has become a very popular research topic,and it has been widely used in bioengineering,medicine,food processing and other fields because of its rich active substances,simple generating devices and lower gas temperature.In this paper,the formation and propagation mechanism of low-temperature plasma jet driven by DC power without air flow is discussed by means of software simulation,experimental research and theoretical analysis.The formation conditions,jet characteristics and the influence factors of uniform array atmospheric pressure low temperature plasma jet are studied.The electrode structure and discharge circuit are optimized.The experiments about fruits and vegetables keeping fresh are carried out and the application value is realized by controlling the plasma parameters.Firstly,the relationship between potential polarity of needle-ring electrode and space electric field distribution is analyzed and the influence of circuit parameters.The discharge characteristics of different electrode parameters and circuit parameters are studied.The formation and propagation mechanism of plasma jet is proposed.The driving factor for the development of plasma jet is that there is always a local strong electric field at the head.The inhomogeneity of the axial and radial electric field intensity is the key factor for the plasma jet propagation.The fundamental reason for the plasma jet to stop propagating is the decrease of the axial electric field intensity.The results show that the stable plasma jet can be formed in the air by applying the heteropolar and the homopolar potential to the needle-ring electrode respectively.Secondly,in this paper,by measuring the emission spectrum of different parameters,the emission spectrums of different axial position of the discharge channel and different voltage are studied,and the best processing parameters of the structure are obtained.The macroscopic temperature of the plasma jet is measured,the molecular vibration temperature is obtained based on the Boltzmann slope method,and the formation mechanism of the active particles is analyzed.The relationship between plasma jets and different materials and different angles of plasma jet units are studied.The results show that we can obtain a lot of active substances to improve the treatment efficiency while keeping the plasma temperature low by reasonably controlling the discharge parameters.Finally,this paper explores the generation method of improving the uniformity of array jet based on the needle-ring electrode with the heteropolar potential,the plasma jets of each array unit developed along the axis are formed.The design scheme applied to the fruits and vegetables fresh-keeping is put forward,and the plasma fresh-keeping effect under different treatment time and different treatment spacing is tested.The results show that under the optimal treatment parameters,the weight loss rate and enzymatic browning rate can be significantly reduced and the storage time is greatly prolonged apple slices because of the action of plasma.