大气压微尺度气体放电中热电子和热场发射的特性分析  

Kinetic Characteristics of DC Thermal Microplasma Based on PIC-MC Model

作　　者：孙丽 周雯 姜巍[2] 李和平[3] 李增耀 SUN Li;ZHOU Wen;JIANG Wei;LI Heping;LI Zengyao(Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education,School of Energy and Power Engineering,Xi’an Jiaotong University,Xi'an 710049,China;School of Physics,Huazhong University of Science and Technology,Wuhan 430007,China;Department of Engineering Physics,Tsinghua University,Beijing 100084,China)

机构地区：[1]西安交通大学能源与动力工程学院,热流科学与工程教育部重点实验室,西安710049 [2]华中科技大学物理学院,武汉430074 [3]清华大学工程物理系,北京100084

出　　处：《工程热物理学报》2023年第1期144-150,共7页Journal of Engineering Thermophysics

基　　金：国家自然科学基金资助项目(No.11775128);国家自然科学基金创新研究小组基金(No.51721004)。

摘　　要：近年来的研究表明,场致电子发射在微尺度气体放电中作用显著。然而,当阴极被加热到高温,热发射也成为影响微尺度放电形成的重要因素。对大气压微尺度放电,热微等离子体的形成主要通过热电子发射和热场发射,气体电离得到的离子能在放电时产生足够的空间电荷,进而影响阴极附近的局部电场。在本文中,针对阴极高温大气压直流微尺度气体放电,采用一维隐式PIC-MC方法,分析了不同场增强因子和极板温度对热电子发射和热场发射产生的等离子体特性的影响。对气体击穿放电达到稳定之后的热微等离子体,分析了极板间电场强度、粒子平均温度、粒子数密度的分布以及电子能量概率分布函数。结果表明,当场增强因子为1时,阴极表面几乎没有场致电子发射,热场发射和热电子发射结果几乎重合;极板温度越高,热发射作用越强。Recent studies have shown that field electron emission plays a significant role in microscale gas discharge. However, when the cathode is heated to a high temperature, thermal emission also becomes an important factor affecting the formation of microscale discharges. For microscale discharges at atmospheric pressure, the thermal microplasma is mainly driven by thermionic emission and thermo-field emission. The ions from electron impact ionization can generate sufficient space charge to modify the local electric field near the cathode. In this paper, for the atmospheric pressure DC microscale gas discharge with hot cathode, the one-dimension implicit PIC-MC method is used to analyze the effects of different field enhancement factors and cathode temperature on the plasma characteristics generated by thermal emission under post-breakdown regime. The distribution of electric field between the electrodes, averaged particle temperature, particle number density, and electron energy probability function are analyzed. The results show that when the field enhancement factor is 1, there is almost no field electron emission from the cathode. The simulation results of thermo-field emission are almost coincided with these of thermionic emission. As the cathode temperature increases, the impacts of thermal emission on electron emission from the cathode become more prominent.

关 键 词：大气压微尺度气体放电 热微等离子体 隐式PIC-MC 特性分析 

分 类 号：O531[理学—等离子体物理]