在等离子体中镁离子谱线MgⅡλ4481?的宽度和位移

本工作测量了MgIIλ4481?(3²D—4²F)在电子数密度为7×10¹⁶—3.1×10¹⁷电子数/cm³范围内的谱线轮廓和位移。采用振荡型电容放电作为光谱光源。在光源中引入水汽,由测量H_β谱线宽度来定电子数密度。观测结果指出,H_β的实验轮廓和Griem-Kolb-Shen的计算结果符合颇好。实验发现MgIIλ4481?谱线向紫方位移,并正比于微观电场的平方;由此定出一个经验上的二级斯塔克效应常数C₄=5.0×10^-14cm⁴/sec。该谱线的轮廓宽度和标准微观电场之间也有平方正比的关系。发现在本实验条件范围内,宽度和位移的比值γ/△保持为常数,其值为γ/△=10.4±0.6。由于谱项4²D的二级斯塔克效应的干扰而产生上能级4²F位移的理论计算虽能说明谱线位移和微观电场间的平方正比关系,但数值偏小于实验结果,指出还有电子贡献的部分。把光谱线的宽度和Lindholm理论公式及Griem等的近似公式作了比较;简单的估计指出,实验结果和后者符合较好。

WIDTH AND SHIFT OF THE Mg II 4481? LINE FROM A PLASMA SOURCE

Line profiles and shifts of the Mg II 4481? line (3²D-4²F) were measured for a range of electron number densities from 7×10¹⁶ to 3.1×10¹⁷ clectrons/c.c. An oscillatory condenser discharge was used as a spectroscopic source. Electron-number densities were determined from measured widths of the H_β line after addition of water vapour to the source. Good fit of the experimental contour of H_β with the theoretical contour based on Griem-Kolb-Shen's calculation was observed. Experimental shifts toward the violet were measured to be proportion to the square of the normal microfield. An empirical quadratic Stark effect constant C₄= 5.0×10^-14cm⁴/sec was determined from these data. The widths of the line profile bear a similar relation with the fields. Ratios of the width to shift, r/△, were found to remain constant in the range of experimental conditions studied. The value is r/△ = 10.4±0.6. Theoretical calculation of the shift of the upper term 4²F due to the quadratic Stark effect perturbation of 4²D term allows one to explain the quadratic dependence on field, but the values of shift are smaller in comparison with experimental data, indicating an additional contribution by electrons. The widths of the line have been compared with the theoretical formula of Lindholm and Griem et al's approximate formula. Simple estimate shows a better agreement with the latter.