介质阻挡放电离子源背景噪声抑制方法数值模拟研究

Shielding of Dielectric Barrier Discharge Ion Source with Wire-Mesh Screen:A Simulation and Theoretical Study

针对单电极介质阻挡放电离子源(DBDI)的外置金属网抑制环境背景噪声技术,采用二维等离子体流体模型进行了数值模拟研究。通过对比施加金属网前后单电极DBDI低温等离子体羽流(LTPP)中各物种的演化发展特性,给出了金属网孔隙参数在调控LTPP效能方面的一般规律。结果表明,金属网通过显著提高DBDI等离子体羽流的亚稳态离子总量并抑制背景杂质离子,从而提升其软电离效果和质谱检测信噪比。特别地,当金属网孔隙为0.5 mm时,亚稳态离子总量占比提高了约5.3倍;各离子密度峰值降低了3倍以上,而He*、N2*的密度峰值则分别增大了7.86倍和2.31倍。随着金属网孔隙不断减小,亚稳态离子总量占比越高,但当孔隙为0.3 mm时,亚稳态离子总量开始减小;在0.3 mm≤g≤0.4 mm范围内,可获得更好的背景离子抑制效果,从而有效抑制背景噪声影响。

We addressed the elimination of environmental interference to single-electrode dielectric barrier discharge ion(DBDI) source.The original work was the wire-mesh screen,shielding DBDI source.The influence of the mesh-size(g) of wire-mesh screen on the behavior of DBDI low-temperature plasma plume(LTPP) was mathematically modeled,theoretically analyzed and numerically simulated.The simulated results show that the mesh-size has a major impact.For example,the wire-mesh screen with mesh-size of 0.5 mm increases the total metastable ions by 5.3 times,heightens the peak densities of He* and N2* by 7.86 times and 2.31 times,respectively,and decreases the peak densities of other ions by over 3 times.As the mesh-size decreases from 0.7 to 0.3 mm,the proportion of metastable ions increases while their total number changes in an increase-decrease manner.We suggest that when it comes to background noises suppression,the optimized mesh-size be 0.3 mm≤g≤0.4 mm.