表面微放电等离子体特性参数计算及介质片性质的影响

Calculation of the Characteristic Parameters of Surface Micro-Discharge and the Effect of Dielectric Sheet Properties

表面微放电(SMD)在不同的领域有着越来越广泛的应用。为了深入理解其放电特性及介质片性质的影响,基于放电物理过程及SMD特有的放电结构,建立了等效电路模型,并联立Boltzmann方程求解器求解电子连续性方程,得到气隙电压、等离子体电阻及电子密度等特性参数。结果表明,对于同一种类不同厚度的介质片,功率相同时的放电面积及各特性参数一致,对于不同种类的介质片,介电常数较大的介质片下SMD的放电功率、气隙电压、等离子体电阻及电子密度随外加电压的变化率较大。在电压相似的情况下,相同厚度下介电常数较大的介质片放电功率及气隙电压更大,等离子体电阻更小。最后通过比较计算功率和测量功率,验证了模型及仿真计算的正确性。

Dielectric barrier discharge(DBD)has the characteristics of high plasma density,a large number of high-energy electrons,low gas temperature,and a wide application range,so it has been widely studied and attracts enormous attention.Surface micro-discharge(SMD)is a kind of DBD with a non-uniform discharge gap.Compared with other atmospheric pressure low-temperature plasma sources,SMD can directly generate a large area of uniform plasma in the air without special rare gases.SMD is widely used in medical sterilization,material modification,pollution control,agriculture,and food industries.The characteristics of SMD are the basis of its application research.The dielectric sheet properties,working gas,and ambient temperature affect the discharge characteristics of SMD.Existing research mainly focuses on the influence of dielectric properties on the discharge intensity and uniformity under uniform gaps.The impact of dielectric parameters on the discharge characteristics of SMD with a non-uniform discharge gap has been studied less.Firstly,SiO2 and Al2O3 dielectric sheets with dielectric parameters of 3.7 and 9.34 are selected,and two thicknesses of 0.5 mm and 1mm are chosen.Then,the variation curve of SMD discharge power under different dielectric parameters is measured,and the voltage and power parameters under three voltage groups are selected.The discharge power of the same dielectric sheet with different thicknesses remains the same.Next,an equivalent circuit model of SMD is established based on the discharge process and the unique discharge structure of SMD.The electron continuity equation is derived by the Boltzmann equation solver.The characteristics of gap voltage,plasma resistance,and electron density are calculated.The results show that for the same kind of dielectric sheet with different thicknesses,the discharge area and the characteristic parameters of SMD are consistent when the discharge power is the same.The discharge power,air gap voltage,plasma resistance,and electron density of SMD under dielectric sheets with larger dielectric constant have a larger rate of change with the applied voltage.It is indicated that the dielectric materials with large dielectric constant have high sensitivity to the electron density adjustment of discharge.Compared with small dielectric constant materials,the same electron density can be obtained under low applied voltage input.Regarding the dielectric sheet with a large dielectric constant and the same thickness,the discharge power,air gap voltage,and electron density are large,and the resistance is small under similar voltage.Finally,the correctness of the model and simulation calculation is verified.The error between the calculated discharge power and the measured power of the proposed SMD circuit model is 10−2 W,and the maximum relative error is less than 7%.This paper provides a reference for parameter selection and structure design of SMD in practical applications.Controlling dielectric properties and discharge power can ensure SMD consistency.The proposed method is effective in selecting thin dielectric plates with large relative dielectric constant,which can reduce the applied voltage and improve the discharge efficiency of SMD.