Analyses of spatiotemporal dynamic behavior of microplasmas near a dielectric surface in microplasma using an optical near field

为了讨论阻挡放电中的等离子体特性并考虑等离子体的有效应用，有必要了解介电表面附近或介电表面的激发态和累积电荷的动力学。我们开发了激光诱导消失模式荧光（LIEF）、交叉光束型LIEF和波导型激光吸收等技术来定量研究微等离子体中受激亚稳态原子在平面平行或共面电极型阻挡放电中的表面反射等表面动力学。我们还开发了一种光学技术，使用电光晶体作为介电屏障，以观察积累的表面电荷的动力学。我们发现，表面电荷的动力学与气体压力密切相关，击穿电压主要由表面电荷密度决定。从这些测量结果出发，利用流光理论讨论了微间隙大气阻挡放电中真击穿电压与等离子体均匀性之间的关系。澄清了表面电荷是由外部光照射调制的。这使得使用外部光照射来控制阻挡放电成为可能。在此基础上，研究了等离子体显示面板的放电机理、二维微阵列型VUV光源在大气压以上工作的特性以及微等离子体射流的特性。本文对常压等离子体在共面型阻挡放电、脉冲调制高频常压放电和微间隙放电下对芽孢杆菌孢子形成菌和致病菌进行了消毒实验。减少了加热，热效应明显，抗菌效果强。

It is necessary to gain knowledge of the dynamics of excited species and accumulated charges near or on the dielectric surface in order to discuss the plasma characteristics in a barrier discharge and to consider efficient plasma applications. We developed techniques such as laser-induced evanescent-mode fluorescence (LIEF), cross-beam type LIEF and waveguide type laser absorption to quantitatively study a surface dynamics such as surface reflection of the excited metastable atoms in a microplasma for a plane parallel or a coplanar electrode type barrier discharge.We also developed an optical technique using an electro-optic crystal as a dielectric barrier in order to observe dynamics of accumulated surface charges. We found that the dynamics of surface charges is strongly dependent on gas pressures and a breakdown voltage is mainly determined by a surface charge density. From these measurements, the relation between true breakdown voltage and plasma homogeneity in a micro-gap atmospheric barrier discharge is discussed using a Streamer theory. It is clarified that the surface charges are modulated by an external irradiation of light. This makes possible to control a barrier discharge using an external light irradiation. Using these results obtained, the discharge mechanism of a plasma display panel, characteristics of a two-dimensional micro-array type VUV light source working at pressures higher than one atmosphere and the property of microplasma jet are investigated.We made experiments for disinfection of Bacillus spore forming bacteria and pathogenic species using atmospheric pressure plasma in a coplanar type barrier discharge, a pulse-modulated high frequency atmospheric discharge and a micro-gap discharge. The reduction of the heating, thermal effect and significantly strong antibacterial effect are realized.