We have observed enhanced emission of the O VIII H alpha line at 121 ev from a recombining plasma produced by laser heating of a thin Formvar foil with two opposed cylindrically focused (0. 3 multiplied by 1. 4 cm) 5-TW laser beams. The time-dependent intensity of the H alpha line increases by nearly an order of magnitude as the plasma length is increased from 0. 27 to 1. 27 cm. This increase in intensity is greater than that expected from a medium exhibiting no gain. A comparison of the measured time history of the emission with that of non-local thermodynamic equilibrium time-dependent calculations suggests that a small-signal gain approximately 0. 5 cm** minus **1 is obtained.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)