电子束离子阱对中性气体电荷交换的光谱诊断

Charge-exchange spectroscopic diagnostics for neutral gas in electron beam ion trap

在实验室天体物理研究中,电子束离子阱(EBIT)是极端紫外(EUV)和X射线波段能谱分析的重要实验平台,其中EBIT中心残余的中性气体对离子产生存在显著影响。研究了阱区中心残余中性气体对电荷态分布的影响,发现阱区中心残余中性气体和高电荷态离子之间的电荷/能量交换过程不仅影响离子的电荷分布,而且对激发函数(离子分布比例随电子能量关系曲线)有着极大的影响。利用电离平衡分析方法成功诊断出阱区中心区域残留的中性气体分子数密度,以及内腔室的真空度。

Electron beam ion traps(EBITs)play an important role on extreme ultra-violet(EUV)and X-ray spectroscopy in laboratory astrophysics.Residual neutral gas in the EBIT trap center has a significant effect on ion breeding.In this work,we investigated the effect of residual neutral gas on the charge state distribution,as well as the diagnostic for the pressure in the trap center.The charge/energy exchange process between the neutral gas and highly charged ions not only affects the ionic fraction,but also plays an important role in fitting the excitation function(namely the relation curve of ionic fraction as a function of electron energies).By using the ionization equilibrium method on the measured excitation function,we have successfully estimated the residual neutral gas in the ion-electron interaction region of the trap center,as well as the vacuum pressure at the trap center.