电四极跃迁对电子束离子阱等离子体中离子能级布居的影响

Effects of electric quadrupole transitions on ion energy-level populations of in electron beam ion trap plasma

在稳态近似下,通过构建三能级体系碰撞辐射模型,解析研究了电四极(E2)跃迁对等离子体中离子能级布居的影响.研究发现,随着原子序数增加,E2跃迁速率逐渐增强,E2跃迁在低电子密度条件下对离子能级布居的影响愈发显著.进一步地,以电子束离子阱中类铁钼(Z=42)和铀(Z=92)等离子体为例,数值求解了包含不同退激通道的离子能级布居.在此基础上,分析了考虑E2退激通道导致的能级布居变化对基组态磁偶极(M1)跃迁线强比的影响,并指出在利用高离化态离子M1跃迁线强比进行等离子体电子密度诊断时E2退激发通道的重要性.

The effects of electric-quadrupole(E2)transitions on ion energy-level populations in plasma are studied by constructing the collisional radiative model of a three-level atomic system in the steady-state approximation.It is found that the influence is non-negligible at the low electron density,and becomes larger when the E2 transition rate grows with atomic number increasing.Furthermore,we investigate the E2-transition effects on the populations of levels in the ground configuration for Fe-like Moand Uions in an electron-beam iontrap plasma.The level populations are obtained by solving the large-scale rate equation numerically.On this basis,we discuss the influence of the E2 transition on the line intensity ratio of the magnetic dipole(M1)lines.In addition,we point out the significance of the E2 transitions on the intensity ratio of the M1 lines that can be used to diagnose the electron density of plasma.