Why the values of the intensity ratio of doublet spectra of the laser-produced plasma spectrum differ from the theoretical value of the intensity ratio given in NIST data.
In experiment one observe surface brightness of the plasmoid. To recalculate this observed value from the known volume emissivity of plasma (calculated from reference data) for instance, it is necessary to calculate the brightness of plasmoid radiation in a certain direction (for axisymmetric objects this is done using the Abel transformation) taking into account reabsorption of radiation, as written in the previous post, as well as the light amplification due to stimulated emission, which is often missed. From my point of view, these issues are most clearly and fully described in the book by Ya. B. Zeldovich and Yu. P. Raizer "Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena", Chapters II and V.
Thank you very much Dr. Zhenlin Hu , Dr. Mikhail Yu. Yakimov and Dr. Yuriy Z Ionikh for valuable answers. by studying your answers I completely understand why basically intensity ratio measured value and NIST value different.