Characteristics of a line-focused laser-produced plasma as an x-ray gain medium

This paper presents our experimental investigation on the characteristics of a laser-produced silicon plasma column as an x-ray gain medium in which the soft x-ray spontaneous emission amplification is successfully demonstrated. It is found that the soft x-ray emission from 5−100 A of the plasma under these conditions is mainly contributed by the He-like (Si 12+ ) ions going to the Li-like (Si 11+ ) ions by recombination radiation and to transition emission the Li-like n=3−n=2 ions; the strongest emissions occur at about 130 μm from the target surface, with a corresponding electron density of 3×10 20 /cm 3