Demonstration of soft x-ray laser of Ne-like Ar at 69.8 nm pumped by capillary discharge

The demonstration of a 69.8nm laser on 3p (3)P(2) - 3s (1)P(1) (J = 2 - 1) transition of Ne-like Ar pumped by capillary discharge is reported in this Letter. A main current of 12 kA with rise time of 43 ns was chosen to generate the plasma in a 35cm long capillary filling with pressure of Ar as low as 11 Pa, resulting in a gain coefficient of 0.34 cm(-1) and gain-length product of 11 at 69.8nm. Also observed is a weak laser on 3p (3)D(2) - 3s (3)P(1) (J = 2 - 1) transition of Ne-like Ar at 72.6nm in the same condition. In addition, multiwavelength lasing at 46.9, 69.8, and 72.6nm was simultaneously realized in a capillary discharge plasma column, conditioning the pressure of Ar to 13 Pa. (C) 2011 Optical Society of America