用于激光尾波加速的弯曲毛细管内气流运动的模拟研究  

Simulation study on gas flow in curved capillary used in laser wakefield acceleration

作　　者：赵月琪 崔佩霖 李建龙 李博原 祝昕哲 陈民 刘振宇[1] Zhao Yue-Qi;Cui Pei-Lin;Li Jian-Long;Li Bo-Yuan;Zhu Xin-Zhe;Chen Min;Liu Zhen-Yu(School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;School of Physics and Astronomy,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学机械与动力工程学院,上海200240 [2]上海交通大学物理与天文学院,上海200240

出　　处：《物理学报》2023年第18期297-306,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11991074);上海交通大学激光等离子体教育部重点实验室2022年度开放课题资助的课题。

摘　　要：高压放电充气毛细管可产生等离子体通道,用于激光尾波加速.为探究尾波级联加速所使用毛细管内的气体流动及分布规律,本文建立了基于标准k-ε模型的弯曲毛细管内气体流动计算模型.以氦气为工质,对弯曲毛细管内可压气体流动过程进行数值模拟,分析了不同结构、充气背压、充气口位置对毛细管内气体密度分布及速度场的影响.结果表明:双侧对冲弯曲毛细管在充气口之间管段具有较为稳定的气体密度分布,充气口附近气体密度波动随充气口与毛细管两端距离的增大而减小;在“直+弯”结构的级联加速毛细管中,负责电子注入的直通道口径会对弯管内气体密度分布造成影响,当电子注入通道口径小于150μm时,弯曲毛细管内气体流动受到直通道的影响较小,可作为级联结构中的电子束导引通道.Based on the standard k-e model,a gas flow calculation model in a curved capillary is established,and the flow process of helium working medium in a curved capillary with gradually changing curvature is numerically simulated.Compared with other methods of studying micro-scale gas flow,this simulation obtains the gas density distribution in the curved capillary more conveniently,and has the same variation trend as the experimental measurement of the plasma electron density distribution,and can predict the gas flow distribution in the tube more accurately.The situation provides a theoretical basis for designing the discharge capillary experiment.Based on this model,the gas flow process in the capillary of the one-sided direct flushing,double-sided hedging and“straight+curved”cascade acceleration structures are numerically simulated.The results and conclusions are summarized as follows.1)Comparing with the single-sided straight-bent capillary structure,the gas density fluctuation between the left gas inlet and the right gas inlet of the double-sided hedging-bend capillary is smaller,the gas flow is more stable,and a relatively stable plasma density channel can be generated.2)In the double-sided hedged curved capillary,a relatively uniform gas density distribution is formed between the two inlets of the capillary under the same inflation back pressure;further research results show that a more uniform plasma density distribution with different lengths can be obtained by controlling the position of the gas inlet.3)In the“traight+curved”cascaded accelerating capillary structure,the diameter of the electron injection channel will affect the gas density distribution in the bend.When the diameter of the electron injection channel is small,the absolute pressure in the capillary is low.The larger pressure difference between them will lead to a higher gas flow rate in the elbow,which will increase the fluctuation of the gas density in the elbow;the final research shows that the diameters of the electron injection chan

关 键 词：弯曲毛细管 可压流动 气体密度 激光尾波加速 

分 类 号：O552.421[理学—热学与物质分子运动论]