Excited-level populations in C IV in a recombining Θ-pinch plasma

Absolute intensities of various transitions from n=3, 4, 5, 6, and 7 levels in C IV ions have been measured in the recombination phase of a Θ-pinch plasma. The discharge vessel was filled with 1.87 Pa (14 mTorr) of acetylene and 0.07 Pa (0.5 mTorr) of hydrogen gas to generate the plasma. The deduced upper-level populations showed inversions for all levels of n=4 and above. An experiment to produce laser gain at 253.0 nm showed only a factor of 6 enhancement in the line intensity, i.e., there was no lasing