中文摘要：

在大气压下利用ns级上升沿高压脉冲电源实验可产生氦等离子体jet,该jet在空气中可长达5 cm。应用高速摄影观测到该等离子体jet实际上类似于一个等离子体弹头,在低场强下其速度可达150 km/s。为了深入了解这一放电现象的物理机制,采用基于光致电离的物理模型研究了这一现象。计算结果表明,在外加电场仅为50V/m以及流注头部电荷数为7×10^9时,该流注可以160 km/s速度在空气中实现自持传播,这一计算结果与实验测量的值误差〈10%。由此可以认为光致电离在这种等离子体jet的传播过程中起到至关重要的作用。

英文摘要：

An atmospheric pressure helium plasma jet with a length of up to 5 cm in the surrounding air can be produced by nano-second high voltage test. High-speed photographs show that the plasma jet actually likes a plasma bullet, which propagates at a maximum velocity of 1.5 105 m/s under unusual low external electric field. In order to understand the discharge mechanism deeply, in this paper, a simple model based on photoionization is developed. And at the same time, the Computational Fluid Dynamics （CFD） method （a scientific fluid software, FLUENT） is used to simulate the distribution of fluid fields. It is found that the streamer head with a charge number of 7 ×10^9 can self-propagate at a velocity of 1.6×10^5 m/s under an external electric field of only 50 V/cm, which is less than 10% difference with the experimental results. So the conclusion can be drawn that the photoionization plays an key role in the propagation of this jet.