We demonstrate a neonlike argon-ion x-ray laser, using a short-pulse laser-
irradiated gas puff target. The gas puff target was formed by pulsed inject
ion of gas from a high-pressure solenoid valve through a nozzle in the form
of a narrow slit and irradiated with a combination of long, 600-ps and sho
rt, 6-ps high-power laser pulses with a total of 10 J of energy in a travel
ing-wave excitation scheme. Lasing was observed on the 3p S-1(0) --> 3s(1)P
(1) transition at 46.9 nm and the 3d(1)P(1) --> 3p(1)P(1) transition at 45.
1 nm. A gain of 11 cm(-1) was measured on these transitions for targets up
to 0.9 cm long. (C) 2001 Optical Society of America.