110 GHz微波电离大气产生等离子体过程的理论研究

将描述电磁波的Maxwell方程组和简化的等离子体流体方程组耦合数值求解,对110 GHz微波电离大气产生等离子体的过程进行了理论研究. 研究发现:在高气压下等离子体成丝状;中等气压下等离子体先成丝状,在向微波源移动的过程中逐渐向连续的等离子体区域过渡;低气压下电离产生连续的等离子体区域. 不同气压下等离子体区域都向微波源方向移动. 初始电子数密度分布只影响放电初始阶段的等离子体区域形状,不会影响成丝与否. 等离子体区域在垂直于电场方向和平行于电场方向的移动规律不同. 当电场平行于计算平面时,由于沿着电场方向等离子体两端存在强场区,等离子体区域被拉长,在较低的气压下会出现等离子体丝阵. 关键词： 110 GHz微波 大气电离 等离子体丝阵

Modeling of plasma pattern formation in 110 GHz microwave air breakdown

Plasma pattern formation in 110 GHz microwave air breakdown is investigated by numerical solution of fluid-based plasmas equations coupled with the Maxwell equations. It is found that the filamentary plasmas are observed at high pressure, the filamentary plasmas transit to diffuse plasma at medium pressure, and the diffuse plasma is obtained at low pressure. The plasmas region propagates toward the microwave source. The distribution of initial electrons influences merely plasmas pattern at first stage, but not final plasmas pattern. The movements in the directions parallel and vertical to electric field are different. Due to the strong electric field at the poles of the plasmas region, the plasmas are elongated in the direction of electric field, forming the filamentary plasmas at much low pressure in E plane.