辐射入射圆柱螺纹中的辐射转移VI。氢氦系统
Radiative transfer in cylindrical threads with incident radiation VI. A hydrogen plus helium system
摘要：
氦的谱线通常在太阳上观测到。这些观测包含了太阳外部结构的物理条件和He/H丰度变化的重要信息。在氢和氦谱线中可见的色球和日冕环状结构的建模需要使用基于圆柱几何中NLTE辐射转移的适当诊断工具。我们采用迭代数值方法求解NLTE辐射转移方程和原子能级布居数的统计平衡方程。这些方程交替求解氢和氦原子，使用圆柱坐标和规定的太阳入射辐射。电子密度由两个原子的电离平衡决定。包括二维效应。分析了主氦谱线的形成机理，并对圆柱体内部的氦源进行了定位。研究了谱线强度随温度、压力和氦丰度的变化。同时计算的氢和氦线，执行新的数值代码，允许环路模型的建设，包括扩展的温度范围。
英文摘要：
Spectral lines of helium are commonly observed on the Sun. These observations contain important informations about physical conditions and He/H abundance variations within solar outer structures. The modeling of chromospheric and coronal loop-like structures visible in hydrogen and helium lines requires the use of appropriate diagnostic tools based on NLTE radiative tranfer in cylindrical geometry. We use iterative numerical methods to solve the equations of NLTE radiative transfer and statistical equilibrium of atomic level populations. These equations are solved alternatively for the hydrogen and helium atoms, using cylindrical coordinates and prescribed solar incident radiation. Electron density is determined by the ionization equilibria of both atoms. Two-dimension effects are included. The mechanisms of formation of the principal helium lines are analyzed and the sources of emission inside the cylinder are located. The variations of spectral line intensities with temperature, pressure, and helium abundance, are studied. The simultaneous computation of hydrogen and helium lines, performed by the new numerical code, allows the construction of loop models including an extended range of temperatures.
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