Time Development of Amplification in Na XI Hα-Line at 54.19 Å

Temporal behavior of the Na XI Balmer-α (Hα) transition in a laser-produced. NaF plasma is experimentally investigated. The time variation of the gain value was derived from the ratio of the Hα intensities along and transverse to the x-ray laser axis. The Na XI Hα line is amplified during 100-500 psec after laser irradiation with the maximum gain of 2-4 cm−1. The experimental result is in close agreement with a model calculation using a 2-dimensional hydrodynamic code.