Experimental investigation of lasing condition for soft X-ray laser pumped by capillary discharge

This paper studies the lasing condition at lower pressure of argon with experiment. In the experiment the laser spike of 46.9 nm Ne-like argon pumped by capillary discharge was measured with X-ray diode (XRD). Changing the wave form of the main current while other experimental parameters being unchanged, the laser spike and the position of background light were contrasted. The results show that the lasing time is approximately 40 ns that is almost a fixed value within a small range when the rise-time of the main current changes. The laser spike appears approaching to the peak of the background light at 23 Pa argon pressure. The laser occurs at stagnation stage of plasma which means that the plasma has been compressed to axis. Therefore, the experimental results verify that soft-X-ray laser only conies into being when electron temperature and electron pressure of plasma reach its optimum range simultaneously, and the time, in which the main current needs to heat the plasma to a suitable temperature for lasing, is a relatively fixed value and does not depend on the rise-time of the main current.