用于中子管的微波离子源放电特性的仿真研究

Simulation Study on Discharge Characteristics of Microwave Ion Source for Neutron Tube

微波离子源作为一种无阴极离子源,与潘宁离子源相比具有电离度高、形成的等离子体密度高、寿命长等优点。为了深入了解用于中子管微波离子源的放电特性,根据微波离子源的放电原理,设计中子管微波离子源的几何结构和所需磁铁的结构。结合Comsol多物理场仿真软件中的二维轴对称的AC/DC模块和微波等离子体模块,采用控制变量法,通过仿真实验探究了放电气压、微波输入功率、放电腔室大小以及放电腔室外壁材料对电子密度的影响,总结了电子密度在不同参数下的规律,将为中子管微波离子源的实验和设计提供重要支撑。

The discharge in cavity of microwave ion source,an advanced component of neutron tube,was mathematically modeled,theoretically analyzed and numerically simulated with software Comsol for design optimization.The influence of the discharge conditions,including the magnetic field profile,pressure,microwave input power,size and layered materials of cavity-wall,on the electron density was investigated.The results show that a descending impact-factor may exist:magnetic-field distributions > pressure > cavity surface material > cavity-size(microwave-power).For example,the triple permanent-magnet rings provide the gyromagnetic field and confinement of electron and ions;and as the pressure increases,e-density significantly increased.The effect of the microwave power,size and surface property of cavity wall on the e-density was also tentatively discussed.We suggest that the simulated results be of some basic and technological interest in design optimization of neutron tube.