摘要
在无外加激励源存在的条件下,不同的等离子体初始参数对衰亡等离子体特性,特别是其内部粒子输运特性的影响会表现出与准稳态等离子体条件下不同的物理规律。为此以激光共振电离所产生的等离子体为研究对象,采用理论分析与粒子模拟相结合的手段,研究了在平行板直流电场作用下衰亡等离子体中带电粒子的输运特性,着重分析了初始电子温度对离子输运特性的影响规律,建立了产生离子输运初始电子温度效应的临界电子数密度判据。研究结果表明:衰亡等离子体在外加直流电场作用下的粒子输运特性会受到初始电子温度和电子数密度、外加电压幅值以及极板间距等多个因素的影响。在外加直流电压与极板间距保持不变的情况下,存在1个临界的电子数密度。当等离子体初始电子数密度低于这一临界数密度值时,初始电子温度将无法影响等离子体衰亡过程中的离子通量;而当初始电子数密度高于这一临界值时,离子衰亡时间将随着初始电子温度的升高而显著缩短。该研究结果在一定程度上揭示了等离子体衰亡过程中初始电子温度和电子数密度对带电粒子输运特性的耦合作用机制,也为实际应用中以提高离子引出效率为目标的关键等离子体初始参数和引出区域结构与工作参数等的调控提供了理论上的指导。
On condition that there exist no external excitation sources,influences of various initial plasma parameters on the characteristics of decaying plasmas,especially the particle transport features,are quite different from those occurring in quasi-steady plasmas.Consequently,we investigated the particle transport characteristics of a decaying plasma induced by the laser resonance photoionization method and confined between two electrostatically biased parallel plates.Based on the analytical and particle simulation methods,the influences of the initial electron temperature on the ion transport characteristics were investigated.A new criterion of the electron number density for determining the electron temperature effect on the ion transport process was established.The analytical and numerical results show that:(i)The ion transport features in the decaying plasmas under an externally electrostatic field can be influenced by various parameters,e.g.,the initial electron temperature and number density,the amplitude of the externally applied voltage,and the gap spacing between electrodes;(ii)With a constant external voltage and gap spacing,there exists a critical value of electron number density,and the initial electron temperature has no effects on the ion transport process when the initial electron number density is lower than the critical electron number density;(iii)Once the initial electron number density is higher than its critical value,the decaying time of ions will decrease significantly with the increase of the initial electron temperature.The results in the study reveal the coupling mechanisms of the initial electron temperature and number density on the transport properties of the charged particles in the decaying plasmas.The results also provide a guidance for the adjustment of the initial key plasma parameters,geometrical and operating parameters of the ion extractors aiming at improving the ion extraction efficiency.
作者
陈坚
李静
李和平
姜东君
周明胜
CHEN Jian;LI Jing;LI Heping;JIANG Dongjun;ZHOU Mingsheng(Department of Engineering Physics,Tsinghua University,Beijing 100084,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2020年第2期729-736,共8页
High Voltage Engineering
基金
国家自然科学基金(11775128).
关键词
衰亡等离子体
粒子输运
初始电子温度
临界电子数密度
粒子模拟
decaying plasma
particle transport
initial electron temperature
critical electron number density
particle simulation
作者简介
陈坚,1994—,男,博士生,主要从事离子引出模拟与实验研究,E-mail:1358148028@qq.com;李静,1995—,女,博士生,主要从事大气压辉光放电模拟与实验研究,E-mail:JingL59@163.com;通信作者:李和平,1973—,男,博士,特别研究员,博导,IET Fellow,IEEE Senior Member,中国电子学会高级会员,中国物理学会会员,中国核学会高级会员主要从事非平衡态等离子体协同输运机制的基础及应用研究,主持国家自然科学基金、航空科学基金、国际合作项目等,E-mail:liheping@tsinghua.edu.cn;姜东君,1976—,男,博士,副研究员,博导,主要从事同位素分离和气体输运的基础研究,主持国家自然科学基金、国际合作交流基金项目等E-mail:jiangdj@mail.tsinghua.edu.cn;周明胜,1968—,男,博士,教授,博导,中国核学会同位素分离分会副理事长,主要从事同位素分离研究,主持国家自然科学基金等多项课题,E-mail:zhoumsh@mail.tsinghua.edu.cn
